Re: [AFMUG] OT Raspberry PI

[Dave]

yeah,, not so much sound like some adtran gear needed


On 02/22/2018 05:16 PM, ch...@wbmfg.com wrote:
I have to generate an alternate mark inversion signal on 1.544 MHz 
with every 193rd bit following a t1 framing sequence.

Sure wish a 555 could do that.
*From:* Dave
*Sent:* Thursday, February 22, 2018 4:10 PM
*To:* af@afmug.com
*Subject:* Re: [AFMUG] OT Raspberry PI
Find a 555 timer ... I used many in the olden day when radioshacks 
were king LOL!



On 02/22/2018 05:05 PM, ch...@wbmfg.com wrote:
I am thinking of using some shift registers instead of using the PI 
output directly as the timing signal.

Use the PI to load them.
I love me some hardware design anyhow
*From:* Colin Stanners
*Sent:* Thursday, February 22, 2018 3:59 PM
*To:* af@afmug.com
*Subject:* Re: [AFMUG] OT Raspberry PI
Other than setting the process priority, you may need a custom 
kernel. See 
https://medium.com/@metebalci/latency-of-raspberry-pi-3-on-standard-and-real-time-linux-4-9-kernel-2d9c20704495 


On Feb 22, 2018 4:48 PM, <ch...@wbmfg.com> wrote:

Anyone know how to get my program to run on bare metal?
Or at the very least tell Linux that my program is the most
important thing in the world and service it above all other things.
I am trying to create a timing signal with the Pi.  It is doing
it but the jitter is pretty bad.
I have researched trying to use an interrupt but there is a
pretty low limit on how many times per second you can fire a
hardware interrupt.
Too low for my application.



--


--

Re: [AFMUG] OT Raspberry PI

[chuck]

Gag.  I always hated dealing with DMA controllers.  
I think I have a solution with the gates.  It is old school but I really don’t 
have to have the Pi do anything but insert that one single bit at an 8 Khz rate.

From: Chuck Macenski 
Sent: Friday, February 23, 2018 12:10 PM
To: af@afmug.com 
Subject: Re: [AFMUG] OT Raspberry PI

Your other option would be to find a way to setup an internal DMA controller to 
trigger off of an external input. From your clock source, you would trigger 
individual DMAs from a static buffer to GPIO connected to some sort of circuit 
to invert the Mark bits. The DMA controller would loop over the buffer and the 
jitter would be limited to that of your 1.544 MHz reference clock source. For 
Raspberry PI, you might be looking at writing a kernel driver/module assuming 
you can find documentation on the CPU and DMA controllers. Might be easier with 
an STM32 like CPU (small, cheap, and potentially Linux free if you are into 
that sort of thing).  



On Fri, Feb 23, 2018 at 10:35 AM, Bill Prince <part15...@gmail.com> wrote:

  1/4 microsecond is too much jitter?

  I don't think the pi is going to be your solution.


  bp
  <part15sbs{at}gmail{dot}com>


  On 2/22/2018 5:22 PM, Chuck McCown wrote:

I have about 250 nS of jitter on my output signal. 

Re: [AFMUG] OT Raspberry PI

[Chuck Macenski]

Your other option would be to find a way to setup an internal DMA
controller to trigger off of an external input. From your clock source, you
would trigger individual DMAs from a static buffer to GPIO connected to
some sort of circuit to invert the Mark bits. The DMA controller would loop
over the buffer and the jitter would be limited to that of your 1.544 MHz
reference clock source. For Raspberry PI, you might be looking at writing a
kernel driver/module assuming you can find documentation on the CPU and DMA
controllers. Might be easier with an STM32 like CPU (small, cheap, and
potentially Linux free if you are into that sort of thing).



On Fri, Feb 23, 2018 at 10:35 AM, Bill Prince  wrote:

> 1/4 microsecond is too much jitter?
>
> I don't think the pi is going to be your solution.
>
>
> bp
> 
>
> On 2/22/2018 5:22 PM, Chuck McCown wrote:
>
>> I have about 250 nS of jitter on my output signal.
>>
>
>

Re: [AFMUG] OT Raspberry PI

[Bill Prince]

1/4 microsecond is too much jitter?

I don't think the pi is going to be your solution.


bp


On 2/22/2018 5:22 PM, Chuck McCown wrote:
I have about 250 nS of jitter on my output signal. 

Re: [AFMUG] OT Raspberry PI

[chuck]

I don’t know verilog or vhdl.  This stuff happened after college.  GALs and 
PALs were just coming on the scene when I stopped making FSM logic machines and 
started using microcontrollers for everything.  

From: Chuck Macenski 
Sent: Thursday, February 22, 2018 9:48 PM
To: af@afmug.com 
Subject: Re: [AFMUG] OT Raspberry PI

This calls out for an FPGA solution.

On Thu, Feb 22, 2018 at 10:45 PM, Forrest Christian (List Account) 
<li...@packetflux.com> wrote:

  You can get a fpga board which might be suitable for this project (after 
adding appropriate clocks) for around $20 anymore.   One example: 
http://tinyfpga.com/




  On Thu, Feb 22, 2018 at 6:42 PM, Lewis Bergman <lewis.berg...@gmail.com> 
wrote:

They aren't cheap but you could always use an fpga.


On Thu, Feb 22, 2018, 7:35 PM Chuck McCown <ch...@wbmfg.com> wrote:

  No, I saw it, but I already had the Pi so I ignored it and hoped for the 
best.
  I tried it first with arduino.  Just not enough speed.  And it had the 
jitter problem too.

  I have a method using three TTL/CMOS chips that is going to work... I 
think...

  The only thing separating the gps disciplined signal and the T1 will be a 
D flip flop and a few AND/NAND gates.  So that ought to get me super low 
jitter.  

  Trying for stratum I with rubidium hold-over isochronous performance at 
the end of the day.  For cheap.

  From: Forrest Christian (List Account) 
  Sent: Thursday, February 22, 2018 6:27 PM
  To: af 
  Subject: Re: [AFMUG] OT Raspberry PI

  Ok, I think you missed this portion of my email last time:

  "I'm skeptical that you'll be able to generate a bitstream with enough 
accuracy under Linux, without extreme programming measures.
  I'd suggest a digilent chipkit wifire and the arduino ide for this.  You 
should be able to bitbang at least a T1 with this processor (500mhz)"

  Generally the raspberry pi is great for 'tiny server stuff', or 'user 
interface' stuff, and the arduino and/or microcontrollers will work better for 
what you're looking at, since there isn't an operating system in the way.  All 
arduino really is is a c++ ide with some simplified libraries. 

  The wifire product I mentioned is really a PIC32MZ dev board, optimized 
for arduino.  If you've had enough of the arduino ide, you can download the 
microchip ide and program it with a full development kit.


  Honestly for what you are talking about a EUSART in even a low end PIC 
might be able to handle this.  If you program the EUSART into synchronous mode 
you'll just have to stuff a byte into it every 8 bit times and it will clock it 
out for you.  Not sure if the clock rate is adjustable enough for you, but if 
you get a PIC with the NCO peripheral you might be able to dynamically adjust 
the frequency enough to make it work. 

  NCO app sheet:  
http://ww1.microchip.com/downloads/en/AppNotes/90003131A.pdf




  On Thu, Feb 22, 2018 at 3:48 PM, <ch...@wbmfg.com> wrote:

Anyone know how to get my program to run on bare metal?

Or at the very least tell Linux that my program is the most important 
thing in the world and service it above all other things.

I am trying to create a timing signal with the Pi.  It is doing it but 
the jitter is pretty bad.  

I have researched trying to use an interrupt but there is a pretty low 
limit on how many times per second you can fire a hardware interrupt.
Too low for my application.  




  -- 

Forrest Christian CEO, PacketFlux Technologies, Inc.

Tel: 406-449-3345 | Address: 3577 Countryside Road, Helena, MT 59602
forre...@imach.com | http://www.packetflux.com

   







  -- 

Forrest Christian CEO, PacketFlux Technologies, Inc.

Tel: 406-449-3345 | Address: 3577 Countryside Road, Helena, MT 59602
forre...@imach.com | http://www.packetflux.com

   

Re: [AFMUG] OT Raspberry PI

[Mike Hammett]

I'm newly in charge of a Metaswitch environment as well. 




- 
Mike Hammett 
Intelligent Computing Solutions 

Midwest Internet Exchange 

The Brothers WISP 




- Original Message -

From: "Chuck McCown" <ch...@wbmfg.com> 
To: af@afmug.com 
Sent: Friday, February 23, 2018 7:48:19 AM 
Subject: Re: [AFMUG] OT Raspberry PI 




Yes, and one would think that Metaswitch would have a 10 MHz input. 




From: Lewis Bergman 
Sent: Friday, February 23, 2018 6:44 AM 
To: af@afmug.com 
Subject: Re: [AFMUG] OT Raspberry PI 


Every Rubidium GPS timing piece of gear I have ever seen outputs 10MHz. Every 
device that I have ever seen that takes a timing signal requires 10MHz. I 
probably have lead a sheltered life but I haven't seen anything else. 


On Fri, Feb 23, 2018 at 12:06 AM Robert < i...@avantwireless.com > wrote: 


https://en.wikipedia.org/wiki/ECos 

On 2/22/18 5:52 PM, Chuck McCown wrote: 
> That looks great. Did not find a cost anywhere. 
> *From:* Bill Prince 
> *Sent:* Thursday, February 22, 2018 6:47 PM 
> *To:* Motorola III 
> *Subject:* Re: [AFMUG] OT Raspberry PI 
> Try this: http://www.ecoscentric.com/news/press-170314.shtml 
> 
> --bp 
> -- 
> bp 
> part15sbs{at}gmail{dot}com 
> On Thu, Feb 22, 2018 at 3:56 PM, Bill Prince < part15...@gmail.com > wrote: 
> 
> Pretty sure you need RTOS to accomplish this.That will get pretty 
> close to bare metal. 
> 
> -bp 
> -- 
> bp 
> part15sbs{at}gmail{dot}com 
> On Thu, Feb 22, 2018 at 3:36 PM, < ch...@wbmfg.com > wrote: 
> 
> Had the command syntax wrong. 
> But got nice to work. Have to sudo if you use negative nice 
> numbers. 
> It made zero difference in my jitter. I went from 19 to –20 on 
> nice and no change. 
> *From:* ch...@wbmfg.com 
> *Sent:* Thursday, February 22, 2018 4:29 PM 
> *To:* af@afmug.com 
> *Subject:* Re: [AFMUG] OT Raspberry PI 
> The problem is there is a crap ton of stuff out there that needs 
> network sync. And it all has a T1 as an input. 
> But most T1 trunking circuits are getting replaced with SIP. 
> So, I am building a cheap and dirty T1 signal generator that is 
> GPS and rhubidium referenced. The hard part is easy. The easy 
> part should be easy but all the T1 framing chips that used to 
> exist no longer exist. 
> The ones that are out there have massive CPU interfaces and tons 
> of registers that need to get set to get them fired up and 
> running 
> Where is Exar when you need them 
> *From:* Adam Moffett 
> *Sent:* Thursday, February 22, 2018 4:21 PM 
> *To:* af@afmug.com 
> *Subject:* Re: [AFMUG] OT Raspberry PI 
> Tell whoever's got the T1 that 1967 is way behind us and get a 
> new interface. 
> Problem eliminated LOL 
> -- Original Message -- 
> From: ch...@wbmfg.com 
> To: af@afmug.com 
> Sent: 2/22/2018 6:16:45 PM 
> Subject: Re: [AFMUG] OT Raspberry PI 
>> I have to generate an alternate mark inversion signal on 1.544 
>> MHz with every 193rd bit following a t1 framing sequence. 
>> Sure wish a 555 could do that. 
>> *From:* Dave 
>> *Sent:* Thursday, February 22, 2018 4:10 PM 
>> *To:* af@afmug.com 
>> *Subject:* Re: [AFMUG] OT Raspberry PI 
>> Find a 555 timer ... I used many in the olden day when 
>> radioshacks were king LOL! 
>> 
>> 
>> On 02/22/2018 05:05 PM, ch...@wbmfg.com wrote: 
>>> I am thinking of using some shift registers instead of using 
>>> the PI output directly as the timing signal. 
>>> Use the PI to load them. 
>>> I love me some hardware design anyhow 
>>> *From:* Colin Stanners 
>>> *Sent:* Thursday, February 22, 2018 3:59 PM 
>>> *To:* af@afmug.com 
>>> *Subject:* Re: [AFMUG] OT Raspberry PI 
>>> Other than setting the process priority, you may need a 
>>> custom kernel. See 
>>> https://medium.com/@metebalci/latency-of-raspberry-pi-3-on-standard-and-real-time-linux-4-9-kernel-2d9c20704495
>>>  
>>> < 
>>> https://medium.com/@metebalci/latency-of-raspberry-pi-3-on-standard-and-real-time-linux-4-9-kernel-2d9c20704495
>>>  > 
>>> 
>>> On Feb 22, 2018 4:48 PM, < ch...@wbmfg.com > wrote: 
>>> 
>>> Anyone know how to get my program to run on bare metal? 
>>> Or at the very least tell Linux that my program is the 
>>> most important thing in the world and service it above 
>>> all other things. 
>>> I am trying to create a timing signal with the Pi. It is 
>>> doing it but the jitter is pretty bad. 
>>> I have researched trying to use an interrupt but there is 
>>> a pretty low limit on how many times per second you can 
>>> fire a hardware interrupt. 
>>> Too low for my application. 
>> 
>> -- 
> 

Re: [AFMUG] OT Raspberry PI

[Chuck McCown]

Yes, and one would think that Metaswitch would have a 10 MHz input.  

From: Lewis Bergman 
Sent: Friday, February 23, 2018 6:44 AM
To: af@afmug.com 
Subject: Re: [AFMUG] OT Raspberry PI

Every Rubidium GPS timing piece of gear I have ever seen outputs 10MHz. Every 
device that I have ever seen that takes a timing signal requires 10MHz. I 
probably have lead a sheltered life but I haven't seen anything else.

On Fri, Feb 23, 2018 at 12:06 AM Robert <i...@avantwireless.com> wrote:

  https://en.wikipedia.org/wiki/ECos

  On 2/22/18 5:52 PM, Chuck McCown wrote:
  > That looks great.  Did not find a cost anywhere.
  > *From:* Bill Prince
  > *Sent:* Thursday, February 22, 2018 6:47 PM
  > *To:* Motorola III
  > *Subject:* Re: [AFMUG] OT Raspberry PI
  > Try this: http://www.ecoscentric.com/news/press-170314.shtml
  >
  > --bp
  > --
  > bp
  > part15sbs{at}gmail{dot}com
  > On Thu, Feb 22, 2018 at 3:56 PM, Bill Prince <part15...@gmail.com> wrote:
  >
  > Pretty sure you need  RTOS to accomplish this.That will get pretty
  > close to bare metal.
  >
  > -bp
  > --
  > bp
  > part15sbs{at}gmail{dot}com
  > On Thu, Feb 22, 2018 at 3:36 PM, <ch...@wbmfg.com> wrote:
  >
  > Had the command syntax wrong.
  > But got nice to work.  Have to sudo if you use negative nice
  > numbers.
  > It made zero difference in my jitter.  I went from 19 to –20 on
  > nice and no change.
  > *From:* ch...@wbmfg.com
  >         *Sent:* Thursday, February 22, 2018 4:29 PM
  > *To:* af@afmug.com
  > *Subject:* Re: [AFMUG] OT Raspberry PI
  > The problem is there is a crap ton of stuff out there that needs
  > network sync.  And it all has a T1 as an input.
  > But most T1 trunking circuits are getting replaced with SIP.
  > So, I am building a cheap and dirty T1 signal generator that is
  > GPS and rhubidium referenced.  The hard part is easy.  The easy
  > part should be easy but all the T1 framing chips that used to
  > exist no longer exist.
  > The ones that are out there have massive CPU interfaces and tons
  > of registers that need to get set to get them fired up and
  > running
  > Where is Exar when you need them
  >         *From:* Adam Moffett
  > *Sent:* Thursday, February 22, 2018 4:21 PM
  > *To:* af@afmug.com
  > *Subject:* Re: [AFMUG] OT Raspberry PI
  > Tell whoever's got the T1 that 1967 is way behind us and get a
  > new interface.
  > Problem eliminated LOL
  >     -- Original Message --
  > From: ch...@wbmfg.com
  > To: af@afmug.com
  > Sent: 2/22/2018 6:16:45 PM
  > Subject: Re: [AFMUG] OT Raspberry PI
  >> I have to generate an alternate mark inversion signal on 1.544
  >> MHz with every 193rd bit following a t1 framing sequence.
  >>     Sure wish a 555 could do that.
  >> *From:* Dave
  >> *Sent:* Thursday, February 22, 2018 4:10 PM
  >> *To:* af@afmug.com
  >> *Subject:* Re: [AFMUG] OT Raspberry PI
  >> Find a 555 timer ... I used many in the olden day when
  >> radioshacks were king LOL!
  >>
  >>
  >> On 02/22/2018 05:05 PM, ch...@wbmfg.com wrote:
  >>> I am thinking of using some shift registers instead of using
  >>> the PI output directly as the timing signal.
  >>> Use the PI to load them.
  >>> I love me some hardware design anyhow
  >>> *From:* Colin Stanners
  >>> *Sent:* Thursday, February 22, 2018 3:59 PM
  >>> *To:* af@afmug.com
  >>> *Subject:* Re: [AFMUG] OT Raspberry PI
  >>> Other than setting the process priority, you may need a
  >>> custom kernel. See
  >>> 
https://medium.com/@metebalci/latency-of-raspberry-pi-3-on-standard-and-real-time-linux-4-9-kernel-2d9c20704495
  >>> 
<https://medium.com/@metebalci/latency-of-raspberry-pi-3-on-standard-and-real-time-linux-4-9-kernel-2d9c20704495>
  >>>
  >>> On Feb 22, 2018 4:48 PM, <ch...@wbmfg.com> wrote:
  >>>
  >>> Anyone know how to get my program to run on bare metal?
  >>> Or at the very least tell Linux that my program is the
  >>> most important thing in the world and service it above
  >>> all other things.
  >>> I am trying to create a timing signal with the Pi.  It is
  >>> doing it but the jitter is pretty bad.
  >>> I have researched trying to use an interrupt but there is
  >>> a pretty low limit on how many times per second you can
  >>> fire a hardware interrupt.
  >>> Too low for my application.
  >>
  >> --
  >

Re: [AFMUG] OT Raspberry PI

[Chuck McCown]

O, I was googling for cheap fpga but did not find anything that cheap.

From: Forrest Christian (List Account) 
Sent: Thursday, February 22, 2018 9:45 PM
To: af 
Subject: Re: [AFMUG] OT Raspberry PI

You can get a fpga board which might be suitable for this project (after adding 
appropriate clocks) for around $20 anymore.   One example: http://tinyfpga.com/




On Thu, Feb 22, 2018 at 6:42 PM, Lewis Bergman <lewis.berg...@gmail.com> wrote:

  They aren't cheap but you could always use an fpga.


  On Thu, Feb 22, 2018, 7:35 PM Chuck McCown <ch...@wbmfg.com> wrote:

No, I saw it, but I already had the Pi so I ignored it and hoped for the 
best.
I tried it first with arduino.  Just not enough speed.  And it had the 
jitter problem too.

I have a method using three TTL/CMOS chips that is going to work... I 
think...

The only thing separating the gps disciplined signal and the T1 will be a D 
flip flop and a few AND/NAND gates.  So that ought to get me super low jitter.  

Trying for stratum I with rubidium hold-over isochronous performance at the 
end of the day.  For cheap.

From: Forrest Christian (List Account) 
Sent: Thursday, February 22, 2018 6:27 PM
To: af 
    Subject: Re: [AFMUG] OT Raspberry PI

Ok, I think you missed this portion of my email last time:

"I'm skeptical that you'll be able to generate a bitstream with enough 
accuracy under Linux, without extreme programming measures.
I'd suggest a digilent chipkit wifire and the arduino ide for this.  You 
should be able to bitbang at least a T1 with this processor (500mhz)"

Generally the raspberry pi is great for 'tiny server stuff', or 'user 
interface' stuff, and the arduino and/or microcontrollers will work better for 
what you're looking at, since there isn't an operating system in the way.  All 
arduino really is is a c++ ide with some simplified libraries. 

The wifire product I mentioned is really a PIC32MZ dev board, optimized for 
arduino.  If you've had enough of the arduino ide, you can download the 
microchip ide and program it with a full development kit.


Honestly for what you are talking about a EUSART in even a low end PIC 
might be able to handle this.  If you program the EUSART into synchronous mode 
you'll just have to stuff a byte into it every 8 bit times and it will clock it 
out for you.  Not sure if the clock rate is adjustable enough for you, but if 
you get a PIC with the NCO peripheral you might be able to dynamically adjust 
the frequency enough to make it work. 

NCO app sheet:  http://ww1.microchip.com/downloads/en/AppNotes/90003131A.pdf




On Thu, Feb 22, 2018 at 3:48 PM, <ch...@wbmfg.com> wrote:

  Anyone know how to get my program to run on bare metal?

  Or at the very least tell Linux that my program is the most important 
thing in the world and service it above all other things.

  I am trying to create a timing signal with the Pi.  It is doing it but 
the jitter is pretty bad.  

  I have researched trying to use an interrupt but there is a pretty low 
limit on how many times per second you can fire a hardware interrupt.
  Too low for my application.  




-- 

  Forrest Christian CEO, PacketFlux Technologies, Inc.

  Tel: 406-449-3345 | Address: 3577 Countryside Road, Helena, MT 59602
  forre...@imach.com | http://www.packetflux.com

 







-- 

  Forrest Christian CEO, PacketFlux Technologies, Inc.

  Tel: 406-449-3345 | Address: 3577 Countryside Road, Helena, MT 59602
  forre...@imach.com | http://www.packetflux.com

 

Re: [AFMUG] OT Raspberry PI

[Lewis Bergman]

Every Rubidium GPS timing piece of gear I have ever seen outputs 10MHz.
Every device that I have ever seen that takes a timing signal requires
10MHz. I probably have lead a sheltered life but I haven't seen anything
else.

On Fri, Feb 23, 2018 at 12:06 AM Robert <i...@avantwireless.com> wrote:

> https://en.wikipedia.org/wiki/ECos
>
> On 2/22/18 5:52 PM, Chuck McCown wrote:
> > That looks great.  Did not find a cost anywhere.
> > *From:* Bill Prince
> > *Sent:* Thursday, February 22, 2018 6:47 PM
> > *To:* Motorola III
> > *Subject:* Re: [AFMUG] OT Raspberry PI
> > Try this: http://www.ecoscentric.com/news/press-170314.shtml
> >
> > --bp
> > --
> > bp
> > part15sbs{at}gmail{dot}com
> > On Thu, Feb 22, 2018 at 3:56 PM, Bill Prince <part15...@gmail.com>
> wrote:
> >
> > Pretty sure you need  RTOS to accomplish this.That will get pretty
> > close to bare metal.
> >
> > -bp
> > --
> > bp
> > part15sbs{at}gmail{dot}com
> > On Thu, Feb 22, 2018 at 3:36 PM, <ch...@wbmfg.com> wrote:
> >
> > Had the command syntax wrong.
> > But got nice to work.  Have to sudo if you use negative nice
> > numbers.
> > It made zero difference in my jitter.  I went from 19 to –20 on
> >     nice and no change.
> > *From:* ch...@wbmfg.com
> > *Sent:* Thursday, February 22, 2018 4:29 PM
> > *To:* af@afmug.com
> > *Subject:* Re: [AFMUG] OT Raspberry PI
> > The problem is there is a crap ton of stuff out there that needs
> > network sync.  And it all has a T1 as an input.
> > But most T1 trunking circuits are getting replaced with SIP.
> > So, I am building a cheap and dirty T1 signal generator that is
> > GPS and rhubidium referenced.  The hard part is easy.  The easy
> > part should be easy but all the T1 framing chips that used to
> > exist no longer exist.
> > The ones that are out there have massive CPU interfaces and tons
> > of registers that need to get set to get them fired up and
> > running
> > Where is Exar when you need them
> > *From:* Adam Moffett
> > *Sent:* Thursday, February 22, 2018 4:21 PM
> > *To:* af@afmug.com
> > *Subject:* Re: [AFMUG] OT Raspberry PI
> >     Tell whoever's got the T1 that 1967 is way behind us and get a
> > new interface.
> > Problem eliminated LOL
> > -- Original Message --
> > From: ch...@wbmfg.com
> > To: af@afmug.com
> > Sent: 2/22/2018 6:16:45 PM
> > Subject: Re: [AFMUG] OT Raspberry PI
> >> I have to generate an alternate mark inversion signal on 1.544
> >> MHz with every 193rd bit following a t1 framing sequence.
> >> Sure wish a 555 could do that.
> >> *From:* Dave
> >> *Sent:* Thursday, February 22, 2018 4:10 PM
> >> *To:* af@afmug.com
> >> *Subject:* Re: [AFMUG] OT Raspberry PI
> >> Find a 555 timer ... I used many in the olden day when
> >> radioshacks were king LOL!
> >>
> >>
> >>     On 02/22/2018 05:05 PM, ch...@wbmfg.com wrote:
> >>> I am thinking of using some shift registers instead of using
> >>> the PI output directly as the timing signal.
> >>> Use the PI to load them.
> >>> I love me some hardware design anyhow
> >>> *From:* Colin Stanners
> >>> *Sent:* Thursday, February 22, 2018 3:59 PM
> >>> *To:* af@afmug.com
> >>> *Subject:* Re: [AFMUG] OT Raspberry PI
> >>> Other than setting the process priority, you may need a
> >>> custom kernel. See
> >>>
> https://medium.com/@metebalci/latency-of-raspberry-pi-3-on-standard-and-real-time-linux-4-9-kernel-2d9c20704495
> >>> <
> https://medium.com/@metebalci/latency-of-raspberry-pi-3-on-standard-and-real-time-linux-4-9-kernel-2d9c20704495
> >
> >>>
> >>> On Feb 22, 2018 4:48 PM, <ch...@wbmfg.com> wrote:
> >>>
> >>> Anyone know how to get my program to run on bare metal?
> >>> Or at the very least tell Linux that my program is the
> >>> most important thing in the world and service it above
> >>> all other things.
> >>> I am trying to create a timing signal with the Pi.  It is
> >>> doing it but the jitter is pretty bad.
> >>> I have researched trying to use an interrupt but there is
> >>> a pretty low limit on how many times per second you can
> >>> fire a hardware interrupt.
> >>> Too low for my application.
> >>
> >> --
> >
>

Re: [AFMUG] OT Raspberry PI

[Robert]

https://en.wikipedia.org/wiki/ECos

On 2/22/18 5:52 PM, Chuck McCown wrote:

That looks great.  Did not find a cost anywhere.
*From:* Bill Prince
*Sent:* Thursday, February 22, 2018 6:47 PM
*To:* Motorola III
*Subject:* Re: [AFMUG] OT Raspberry PI
Try this: http://www.ecoscentric.com/news/press-170314.shtml

--bp
--
bp
part15sbs{at}gmail{dot}com
On Thu, Feb 22, 2018 at 3:56 PM, Bill Prince <part15...@gmail.com> wrote:

Pretty sure you need  RTOS to accomplish this.That will get pretty
close to bare metal.

-bp
--
bp
part15sbs{at}gmail{dot}com
On Thu, Feb 22, 2018 at 3:36 PM, <ch...@wbmfg.com> wrote:

Had the command syntax wrong.
But got nice to work.  Have to sudo if you use negative nice
numbers.
It made zero difference in my jitter.  I went from 19 to –20 on
nice and no change.
*From:* ch...@wbmfg.com
*Sent:* Thursday, February 22, 2018 4:29 PM
*To:* af@afmug.com
    *Subject:* Re: [AFMUG] OT Raspberry PI
The problem is there is a crap ton of stuff out there that needs
network sync.  And it all has a T1 as an input.
But most T1 trunking circuits are getting replaced with SIP.
So, I am building a cheap and dirty T1 signal generator that is
GPS and rhubidium referenced.  The hard part is easy.  The easy
part should be easy but all the T1 framing chips that used to
exist no longer exist.
The ones that are out there have massive CPU interfaces and tons
of registers that need to get set to get them fired up and
running
Where is Exar when you need them
*From:* Adam Moffett
*Sent:* Thursday, February 22, 2018 4:21 PM
*To:* af@afmug.com
    *Subject:* Re: [AFMUG] OT Raspberry PI
Tell whoever's got the T1 that 1967 is way behind us and get a
new interface.
Problem eliminated LOL
-- Original Message --
From: ch...@wbmfg.com
To: af@afmug.com
Sent: 2/22/2018 6:16:45 PM
    Subject: Re: [AFMUG] OT Raspberry PI

I have to generate an alternate mark inversion signal on 1.544
MHz with every 193rd bit following a t1 framing sequence.
Sure wish a 555 could do that.
*From:* Dave
*Sent:* Thursday, February 22, 2018 4:10 PM
*To:* af@afmug.com
    *Subject:* Re: [AFMUG] OT Raspberry PI
Find a 555 timer ... I used many in the olden day when
radioshacks were king LOL!


On 02/22/2018 05:05 PM, ch...@wbmfg.com wrote:

I am thinking of using some shift registers instead of using
the PI output directly as the timing signal.
Use the PI to load them.
I love me some hardware design anyhow
*From:* Colin Stanners
*Sent:* Thursday, February 22, 2018 3:59 PM
*To:* af@afmug.com
    *Subject:* Re: [AFMUG] OT Raspberry PI
Other than setting the process priority, you may need a
custom kernel. See

https://medium.com/@metebalci/latency-of-raspberry-pi-3-on-standard-and-real-time-linux-4-9-kernel-2d9c20704495

<https://medium.com/@metebalci/latency-of-raspberry-pi-3-on-standard-and-real-time-linux-4-9-kernel-2d9c20704495>

On Feb 22, 2018 4:48 PM, <ch...@wbmfg.com> wrote:

Anyone know how to get my program to run on bare metal?
Or at the very least tell Linux that my program is the
most important thing in the world and service it above
all other things.
I am trying to create a timing signal with the Pi.  It is
doing it but the jitter is pretty bad.
I have researched trying to use an interrupt but there is
a pretty low limit on how many times per second you can
fire a hardware interrupt.
Too low for my application. 


-- 

Re: [AFMUG] OT Raspberry PI

[Forrest Christian (List Account)]

My memory just reminded me that many of these FPGA's also have some really
sophisticated clock synthesis/management blocks.  Like it would not
surprise me that one of them could generate a jitter free 1.544Mhz clock
from say a 10Mhz reference clock out of a Rb oscillator.



On Thu, Feb 22, 2018 at 9:48 PM, Chuck Macenski <ch...@macenski.com> wrote:

> This calls out for an FPGA solution.
>
> On Thu, Feb 22, 2018 at 10:45 PM, Forrest Christian (List Account) <
> li...@packetflux.com> wrote:
>
>> You can get a fpga board which might be suitable for this project (after
>> adding appropriate clocks) for around $20 anymore.   One example:
>> http://tinyfpga.com/
>>
>>
>>
>> On Thu, Feb 22, 2018 at 6:42 PM, Lewis Bergman <lewis.berg...@gmail.com>
>> wrote:
>>
>>> They aren't cheap but you could always use an fpga.
>>>
>>> On Thu, Feb 22, 2018, 7:35 PM Chuck McCown <ch...@wbmfg.com> wrote:
>>>
>>>> No, I saw it, but I already had the Pi so I ignored it and hoped for
>>>> the best.
>>>> I tried it first with arduino.  Just not enough speed.  And it had the
>>>> jitter problem too.
>>>>
>>>> I have a method using three TTL/CMOS chips that is going to work... I
>>>> think...
>>>>
>>>> The only thing separating the gps disciplined signal and the T1 will be
>>>> a D flip flop and a few AND/NAND gates.  So that ought to get me super low
>>>> jitter.
>>>>
>>>> Trying for stratum I with rubidium hold-over isochronous performance at
>>>> the end of the day.  For cheap.
>>>>
>>>> *From:* Forrest Christian (List Account)
>>>> *Sent:* Thursday, February 22, 2018 6:27 PM
>>>> *To:* af
>>>> *Subject:* Re: [AFMUG] OT Raspberry PI
>>>>
>>>> Ok, I think you missed this portion of my email last time:
>>>>
>>>>
>>>> *"I'm skeptical that you'll be able to generate a bitstream with enough
>>>> accuracy under Linux, without extreme programming measures.I'd suggest a
>>>> digilent chipkit wifire and the arduino ide for this.  You should be able
>>>> to bitbang at least a T1 with this processor (500mhz)"*
>>>>
>>>> Generally the raspberry pi is great for 'tiny server stuff', or 'user
>>>> interface' stuff, and the arduino and/or microcontrollers will work better
>>>> for what you're looking at, since there isn't an operating system in the
>>>> way.  All arduino really is is a c++ ide with some simplified libraries.
>>>>
>>>> The wifire product I mentioned is really a PIC32MZ dev board, optimized
>>>> for arduino.  If you've had enough of the arduino ide, you can download the
>>>> microchip ide and program it with a full development kit.
>>>>
>>>> Honestly for what you are talking about a EUSART in even a low end PIC
>>>> might be able to handle this.  If you program the EUSART into synchronous
>>>> mode you'll just have to stuff a byte into it every 8 bit times and it will
>>>> clock it out for you.  Not sure if the clock rate is adjustable enough for
>>>> you, but if you get a PIC with the NCO peripheral you might be able to
>>>> dynamically adjust the frequency enough to make it work.
>>>>
>>>> NCO app sheet:  http://ww1.microchip.com/downl
>>>> oads/en/AppNotes/90003131A.pdf
>>>>
>>>>
>>>>
>>>>
>>>> On Thu, Feb 22, 2018 at 3:48 PM, <ch...@wbmfg.com> wrote:
>>>>
>>>>> Anyone know how to get my program to run on bare metal?
>>>>>
>>>>> Or at the very least tell Linux that my program is the most important
>>>>> thing in the world and service it above all other things.
>>>>>
>>>>> I am trying to create a timing signal with the Pi.  It is doing it but
>>>>> the jitter is pretty bad.
>>>>>
>>>>> I have researched trying to use an interrupt but there is a pretty low
>>>>> limit on how many times per second you can fire a hardware interrupt.
>>>>> Too low for my application.
>>>>>
>>>>
>>>>
>>>>
>>>> --
>>>> *Forrest Christian* *CEO**, PacketFlux Technologies, Inc.*
>>>> Tel: 406-449-3345 | Address: 3577 Countryside Road, Helena, MT 59602
>>>> <https://maps.google.com/?q=3577+Countryside+Road,+Helena,+MT+%0D+59602=gmail=g>
>>>> forre...@imach.com | http://www.packetflux.com
>>>> <http://www.linkedin.com/in/fwchristian>
>>>> <http://facebook.com/packetflux>  <http://twitter.com/@packetflux>
>>>>
>>>>
>>
>>
>> --
>> *Forrest Christian* *CEO**, PacketFlux Technologies, Inc.*
>> Tel: 406-449-3345 | Address: 3577 Countryside Road, Helena, MT 59602
>> <https://maps.google.com/?q=3577+Countryside+Road,+Helena,+MT+59602=gmail=g>
>> forre...@imach.com | http://www.packetflux.com
>> <http://www.linkedin.com/in/fwchristian>
>> <http://facebook.com/packetflux>  <http://twitter.com/@packetflux>
>>
>>
>


-- 
*Forrest Christian* *CEO**, PacketFlux Technologies, Inc.*
Tel: 406-449-3345 | Address: 3577 Countryside Road, Helena, MT 59602
forre...@imach.com | http://www.packetflux.com
<http://www.linkedin.com/in/fwchristian>  <http://facebook.com/packetflux>
<http://twitter.com/@packetflux>

Re: [AFMUG] OT Raspberry PI

[Chuck Macenski]

This calls out for an FPGA solution.

On Thu, Feb 22, 2018 at 10:45 PM, Forrest Christian (List Account) <
li...@packetflux.com> wrote:

> You can get a fpga board which might be suitable for this project (after
> adding appropriate clocks) for around $20 anymore.   One example:
> http://tinyfpga.com/
>
>
>
> On Thu, Feb 22, 2018 at 6:42 PM, Lewis Bergman <lewis.berg...@gmail.com>
> wrote:
>
>> They aren't cheap but you could always use an fpga.
>>
>> On Thu, Feb 22, 2018, 7:35 PM Chuck McCown <ch...@wbmfg.com> wrote:
>>
>>> No, I saw it, but I already had the Pi so I ignored it and hoped for the
>>> best.
>>> I tried it first with arduino.  Just not enough speed.  And it had the
>>> jitter problem too.
>>>
>>> I have a method using three TTL/CMOS chips that is going to work... I
>>> think...
>>>
>>> The only thing separating the gps disciplined signal and the T1 will be
>>> a D flip flop and a few AND/NAND gates.  So that ought to get me super low
>>> jitter.
>>>
>>> Trying for stratum I with rubidium hold-over isochronous performance at
>>> the end of the day.  For cheap.
>>>
>>> *From:* Forrest Christian (List Account)
>>> *Sent:* Thursday, February 22, 2018 6:27 PM
>>> *To:* af
>>> *Subject:* Re: [AFMUG] OT Raspberry PI
>>>
>>> Ok, I think you missed this portion of my email last time:
>>>
>>>
>>> *"I'm skeptical that you'll be able to generate a bitstream with enough
>>> accuracy under Linux, without extreme programming measures.I'd suggest a
>>> digilent chipkit wifire and the arduino ide for this.  You should be able
>>> to bitbang at least a T1 with this processor (500mhz)"*
>>>
>>> Generally the raspberry pi is great for 'tiny server stuff', or 'user
>>> interface' stuff, and the arduino and/or microcontrollers will work better
>>> for what you're looking at, since there isn't an operating system in the
>>> way.  All arduino really is is a c++ ide with some simplified libraries.
>>>
>>> The wifire product I mentioned is really a PIC32MZ dev board, optimized
>>> for arduino.  If you've had enough of the arduino ide, you can download the
>>> microchip ide and program it with a full development kit.
>>>
>>> Honestly for what you are talking about a EUSART in even a low end PIC
>>> might be able to handle this.  If you program the EUSART into synchronous
>>> mode you'll just have to stuff a byte into it every 8 bit times and it will
>>> clock it out for you.  Not sure if the clock rate is adjustable enough for
>>> you, but if you get a PIC with the NCO peripheral you might be able to
>>> dynamically adjust the frequency enough to make it work.
>>>
>>> NCO app sheet:  http://ww1.microchip.com/downl
>>> oads/en/AppNotes/90003131A.pdf
>>>
>>>
>>>
>>>
>>> On Thu, Feb 22, 2018 at 3:48 PM, <ch...@wbmfg.com> wrote:
>>>
>>>> Anyone know how to get my program to run on bare metal?
>>>>
>>>> Or at the very least tell Linux that my program is the most important
>>>> thing in the world and service it above all other things.
>>>>
>>>> I am trying to create a timing signal with the Pi.  It is doing it but
>>>> the jitter is pretty bad.
>>>>
>>>> I have researched trying to use an interrupt but there is a pretty low
>>>> limit on how many times per second you can fire a hardware interrupt.
>>>> Too low for my application.
>>>>
>>>
>>>
>>>
>>> --
>>> *Forrest Christian* *CEO**, PacketFlux Technologies, Inc.*
>>> Tel: 406-449-3345 | Address: 3577 Countryside Road, Helena, MT 59602
>>> <https://maps.google.com/?q=3577+Countryside+Road,+Helena,+MT+%0D+59602=gmail=g>
>>> forre...@imach.com | http://www.packetflux.com
>>> <http://www.linkedin.com/in/fwchristian>
>>> <http://facebook.com/packetflux>  <http://twitter.com/@packetflux>
>>>
>>>
>
>
> --
> *Forrest Christian* *CEO**, PacketFlux Technologies, Inc.*
> Tel: 406-449-3345 | Address: 3577 Countryside Road, Helena, MT 59602
> <https://maps.google.com/?q=3577+Countryside+Road,+Helena,+MT+59602=gmail=g>
> forre...@imach.com | http://www.packetflux.com
> <http://www.linkedin.com/in/fwchristian>  <http://facebook.com/packetflux>
>   <http://twitter.com/@packetflux>
>
>

Re: [AFMUG] OT Raspberry PI

[Forrest Christian (List Account)]

You can get a fpga board which might be suitable for this project (after
adding appropriate clocks) for around $20 anymore.   One example:
http://tinyfpga.com/



On Thu, Feb 22, 2018 at 6:42 PM, Lewis Bergman <lewis.berg...@gmail.com>
wrote:

> They aren't cheap but you could always use an fpga.
>
> On Thu, Feb 22, 2018, 7:35 PM Chuck McCown <ch...@wbmfg.com> wrote:
>
>> No, I saw it, but I already had the Pi so I ignored it and hoped for the
>> best.
>> I tried it first with arduino.  Just not enough speed.  And it had the
>> jitter problem too.
>>
>> I have a method using three TTL/CMOS chips that is going to work... I
>> think...
>>
>> The only thing separating the gps disciplined signal and the T1 will be a
>> D flip flop and a few AND/NAND gates.  So that ought to get me super low
>> jitter.
>>
>> Trying for stratum I with rubidium hold-over isochronous performance at
>> the end of the day.  For cheap.
>>
>> *From:* Forrest Christian (List Account)
>> *Sent:* Thursday, February 22, 2018 6:27 PM
>> *To:* af
>> *Subject:* Re: [AFMUG] OT Raspberry PI
>>
>> Ok, I think you missed this portion of my email last time:
>>
>>
>> *"I'm skeptical that you'll be able to generate a bitstream with enough
>> accuracy under Linux, without extreme programming measures.I'd suggest a
>> digilent chipkit wifire and the arduino ide for this.  You should be able
>> to bitbang at least a T1 with this processor (500mhz)"*
>>
>> Generally the raspberry pi is great for 'tiny server stuff', or 'user
>> interface' stuff, and the arduino and/or microcontrollers will work better
>> for what you're looking at, since there isn't an operating system in the
>> way.  All arduino really is is a c++ ide with some simplified libraries.
>>
>> The wifire product I mentioned is really a PIC32MZ dev board, optimized
>> for arduino.  If you've had enough of the arduino ide, you can download the
>> microchip ide and program it with a full development kit.
>>
>> Honestly for what you are talking about a EUSART in even a low end PIC
>> might be able to handle this.  If you program the EUSART into synchronous
>> mode you'll just have to stuff a byte into it every 8 bit times and it will
>> clock it out for you.  Not sure if the clock rate is adjustable enough for
>> you, but if you get a PIC with the NCO peripheral you might be able to
>> dynamically adjust the frequency enough to make it work.
>>
>> NCO app sheet:  http://ww1.microchip.com/downloads/en/AppNotes/
>> 90003131A.pdf
>>
>>
>>
>>
>> On Thu, Feb 22, 2018 at 3:48 PM, <ch...@wbmfg.com> wrote:
>>
>>> Anyone know how to get my program to run on bare metal?
>>>
>>> Or at the very least tell Linux that my program is the most important
>>> thing in the world and service it above all other things.
>>>
>>> I am trying to create a timing signal with the Pi.  It is doing it but
>>> the jitter is pretty bad.
>>>
>>> I have researched trying to use an interrupt but there is a pretty low
>>> limit on how many times per second you can fire a hardware interrupt.
>>> Too low for my application.
>>>
>>
>>
>>
>> --
>> *Forrest Christian* *CEO**, PacketFlux Technologies, Inc.*
>> Tel: 406-449-3345 | Address: 3577 Countryside Road, Helena, MT 59602
>> <https://maps.google.com/?q=3577+Countryside+Road,+Helena,+MT+%0D+59602=gmail=g>
>> forre...@imach.com | http://www.packetflux.com
>> <http://www.linkedin.com/in/fwchristian>
>> <http://facebook.com/packetflux>  <http://twitter.com/@packetflux>
>>
>>


-- 
*Forrest Christian* *CEO**, PacketFlux Technologies, Inc.*
Tel: 406-449-3345 | Address: 3577 Countryside Road, Helena, MT 59602
forre...@imach.com | http://www.packetflux.com
<http://www.linkedin.com/in/fwchristian>  <http://facebook.com/packetflux>
<http://twitter.com/@packetflux>

Re: [AFMUG] OT Raspberry PI

[Forrest Christian (List Account)]

In case your existing plan doesn't work:

So what frequency are you running out of the rubidium?

I've admittedly never had to deal with a GPS-aligned T1 reference clock.
I'm assuming you both have to control the exact frequency and also the
timing of the superframe, and probably even the edge alignment?

In my mind, the trick with using an arduino (or other small micro) is to
not bit-bang it but instead to clock one of the internal USART's with an
appropriate clock.   Assuming one disciplines an oscillator to some
multiple of the T1 frequency--possibly even exactly the frequency--one
should be able to divide this down and feed it into the external clock
input on the processor, using that to clock out the bitstream which is
generated by the processor.  The only difficult trick will be to adjust the
superframe bits to match the GPS time.  However with the disciplined clock
this should become rather trivial as you should be able to fix this within
a superframe of the T1, and then clock it every 1544 bits as needed.

The clock disciplining could/should also be done with the microcontroller
controlling an OCXO.  If you're clocking late, just adjust the OCXO to run
a bit faster.  Early, run it a bit slower.



On Thu, Feb 22, 2018 at 6:34 PM, Chuck McCown <ch...@wbmfg.com> wrote:

> No, I saw it, but I already had the Pi so I ignored it and hoped for the
> best.
> I tried it first with arduino.  Just not enough speed.  And it had the
> jitter problem too.
>
> I have a method using three TTL/CMOS chips that is going to work... I
> think...
>
> The only thing separating the gps disciplined signal and the T1 will be a
> D flip flop and a few AND/NAND gates.  So that ought to get me super low
> jitter.
>
> Trying for stratum I with rubidium hold-over isochronous performance at
> the end of the day.  For cheap.
>
> *From:* Forrest Christian (List Account)
> *Sent:* Thursday, February 22, 2018 6:27 PM
> *To:* af
> *Subject:* Re: [AFMUG] OT Raspberry PI
>
> Ok, I think you missed this portion of my email last time:
>
>
> *"I'm skeptical that you'll be able to generate a bitstream with enough
> accuracy under Linux, without extreme programming measures.I'd suggest a
> digilent chipkit wifire and the arduino ide for this.  You should be able
> to bitbang at least a T1 with this processor (500mhz)"*
>
> Generally the raspberry pi is great for 'tiny server stuff', or 'user
> interface' stuff, and the arduino and/or microcontrollers will work better
> for what you're looking at, since there isn't an operating system in the
> way.  All arduino really is is a c++ ide with some simplified libraries.
>
> The wifire product I mentioned is really a PIC32MZ dev board, optimized
> for arduino.  If you've had enough of the arduino ide, you can download the
> microchip ide and program it with a full development kit.
>
> Honestly for what you are talking about a EUSART in even a low end PIC
> might be able to handle this.  If you program the EUSART into synchronous
> mode you'll just have to stuff a byte into it every 8 bit times and it will
> clock it out for you.  Not sure if the clock rate is adjustable enough for
> you, but if you get a PIC with the NCO peripheral you might be able to
> dynamically adjust the frequency enough to make it work.
>
> NCO app sheet:  http://ww1.microchip.com/downloads/en/AppNotes/
> 90003131A.pdf
>
>
>
>
> On Thu, Feb 22, 2018 at 3:48 PM, <ch...@wbmfg.com> wrote:
>
>> Anyone know how to get my program to run on bare metal?
>>
>> Or at the very least tell Linux that my program is the most important
>> thing in the world and service it above all other things.
>>
>> I am trying to create a timing signal with the Pi.  It is doing it but
>> the jitter is pretty bad.
>>
>> I have researched trying to use an interrupt but there is a pretty low
>> limit on how many times per second you can fire a hardware interrupt.
>> Too low for my application.
>>
>
>
>
> --
> *Forrest Christian* *CEO**, PacketFlux Technologies, Inc.*
> Tel: 406-449-3345 | Address: 3577 Countryside Road, Helena, MT 59602
> forre...@imach.com | http://www.packetflux.com
> <http://www.linkedin.com/in/fwchristian>  <http://facebook.com/packetflux>
>   <http://twitter.com/@packetflux>
>
>


-- 
*Forrest Christian* *CEO**, PacketFlux Technologies, Inc.*
Tel: 406-449-3345 | Address: 3577 Countryside Road, Helena, MT 59602
forre...@imach.com | http://www.packetflux.com
<http://www.linkedin.com/in/fwchristian>  <http://facebook.com/packetflux>
<http://twitter.com/@packetflux>

Re: [AFMUG] OT Raspberry PI

[Josh Reynolds]

$250ish gets you a 6core ARM and fpga with 4 gig ports anymore

On Feb 22, 2018 7:42 PM, "Lewis Bergman" <lewis.berg...@gmail.com> wrote:

> They aren't cheap but you could always use an fpga.
>
> On Thu, Feb 22, 2018, 7:35 PM Chuck McCown <ch...@wbmfg.com> wrote:
>
>> No, I saw it, but I already had the Pi so I ignored it and hoped for the
>> best.
>> I tried it first with arduino.  Just not enough speed.  And it had the
>> jitter problem too.
>>
>> I have a method using three TTL/CMOS chips that is going to work... I
>> think...
>>
>> The only thing separating the gps disciplined signal and the T1 will be a
>> D flip flop and a few AND/NAND gates.  So that ought to get me super low
>> jitter.
>>
>> Trying for stratum I with rubidium hold-over isochronous performance at
>> the end of the day.  For cheap.
>>
>> *From:* Forrest Christian (List Account)
>> *Sent:* Thursday, February 22, 2018 6:27 PM
>> *To:* af
>> *Subject:* Re: [AFMUG] OT Raspberry PI
>>
>> Ok, I think you missed this portion of my email last time:
>>
>>
>> *"I'm skeptical that you'll be able to generate a bitstream with enough
>> accuracy under Linux, without extreme programming measures.I'd suggest a
>> digilent chipkit wifire and the arduino ide for this.  You should be able
>> to bitbang at least a T1 with this processor (500mhz)"*
>>
>> Generally the raspberry pi is great for 'tiny server stuff', or 'user
>> interface' stuff, and the arduino and/or microcontrollers will work better
>> for what you're looking at, since there isn't an operating system in the
>> way.  All arduino really is is a c++ ide with some simplified libraries.
>>
>> The wifire product I mentioned is really a PIC32MZ dev board, optimized
>> for arduino.  If you've had enough of the arduino ide, you can download the
>> microchip ide and program it with a full development kit.
>>
>> Honestly for what you are talking about a EUSART in even a low end PIC
>> might be able to handle this.  If you program the EUSART into synchronous
>> mode you'll just have to stuff a byte into it every 8 bit times and it will
>> clock it out for you.  Not sure if the clock rate is adjustable enough for
>> you, but if you get a PIC with the NCO peripheral you might be able to
>> dynamically adjust the frequency enough to make it work.
>>
>> NCO app sheet:  http://ww1.microchip.com/downloads/en/AppNotes/
>> 90003131A.pdf
>>
>>
>>
>>
>> On Thu, Feb 22, 2018 at 3:48 PM, <ch...@wbmfg.com> wrote:
>>
>>> Anyone know how to get my program to run on bare metal?
>>>
>>> Or at the very least tell Linux that my program is the most important
>>> thing in the world and service it above all other things.
>>>
>>> I am trying to create a timing signal with the Pi.  It is doing it but
>>> the jitter is pretty bad.
>>>
>>> I have researched trying to use an interrupt but there is a pretty low
>>> limit on how many times per second you can fire a hardware interrupt.
>>> Too low for my application.
>>>
>>
>>
>>
>> --
>> *Forrest Christian* *CEO**, PacketFlux Technologies, Inc.*
>> Tel: 406-449-3345 | Address: 3577 Countryside Road, Helena, MT 59602
>> <https://maps.google.com/?q=3577+Countryside+Road,+Helena,+MT+%0D+59602=gmail=g>
>> forre...@imach.com | http://www.packetflux.com
>> <http://www.linkedin.com/in/fwchristian>
>> <http://facebook.com/packetflux>  <http://twitter.com/@packetflux>
>>
>>

Re: [AFMUG] OT Raspberry PI

[Josh Reynolds]

No, latency is one reason Google is developing a new mobile OS.

On Feb 22, 2018 6:27 PM, "Robert" <i...@avantwireless.com> wrote:

I believe this was a major part of the improvements in android


On 2/22/18 3:58 PM, Bill Prince wrote:

> Pretty sure you need  RTOS to accomplish this.That will get pretty close
> to bare metal.
>
> -bp
>
> --
> bp
> part15sbs{at}gmail{dot}com
>
> On Thu, Feb 22, 2018 at 3:36 PM, <ch...@wbmfg.com <mailto:ch...@wbmfg.com>>
> wrote:
>
> Had the command syntax wrong.
> But got nice to work.  Have to sudo if you use negative nice numbers.
> It made zero difference in my jitter.  I went from 19 to –20 on nice
> and no change.
> *From:* ch...@wbmfg.com
> *Sent:* Thursday, February 22, 2018 4:29 PM
> *To:* af@afmug.com
> *Subject:* Re: [AFMUG] OT Raspberry PI
>
> The problem is there is a crap ton of stuff out there that needs
> network sync.  And it all has a T1 as an input.
> But most T1 trunking circuits are getting replaced with SIP.
> So, I am building a cheap and dirty T1 signal generator that is GPS
> and rhubidium referenced.  The hard part is easy.  The easy part
> should be easy but all the T1 framing chips that used to exist no
> longer exist.
> The ones that are out there have massive CPU interfaces and tons of
> registers that need to get set to get them fired up and running
> Where is Exar when you need them....
> *From:* Adam Moffett
> *Sent:* Thursday, February 22, 2018 4:21 PM
> *To:* af@afmug.com
> *Subject:* Re: [AFMUG] OT Raspberry PI
>
> Tell whoever's got the T1 that 1967 is way behind us and get a new
> interface.
> Problem eliminated LOL
>     -- Original Message --
> From: ch...@wbmfg.com
> To: af@afmug.com
> Sent: 2/22/2018 6:16:45 PM
> Subject: Re: [AFMUG] OT Raspberry PI
>
>> I have to generate an alternate mark inversion signal on 1.544 MHz
>> with every 193rd bit following a t1 framing sequence.
>> Sure wish a 555 could do that.
>> *From:* Dave
>> *Sent:* Thursday, February 22, 2018 4:10 PM
>> *To:* af@afmug.com
>> *Subject:* Re: [AFMUG] OT Raspberry PI
>>
>> Find a 555 timer ... I used many in the olden day when radioshacks
>> were king LOL!
>>
>>
>> On 02/22/2018 05:05 PM, ch...@wbmfg.com wrote:
>>
>>> I am thinking of using some shift registers instead of using the
>>>     PI output directly as the timing signal.
>>> Use the PI to load them.
>>> I love me some hardware design anyhow
>>> *From:* Colin Stanners
>>> *Sent:* Thursday, February 22, 2018 3:59 PM
>>> *To:* af@afmug.com
>>> *Subject:* Re: [AFMUG] OT Raspberry PI
>>>
>>> Other than setting the process priority, you may need a custom
>>> kernel. See
>>> https://medium.com/@metebalci/latency-of-raspberry-pi-3-on-s
>>> tandard-and-real-time-linux-4-9-kernel-2d9c20704495
>>> <https://medium.com/@metebalci/latency-of-raspberry-pi-3-on-
>>> standard-and-real-time-linux-4-9-kernel-2d9c20704495>
>>>
>>> On Feb 22, 2018 4:48 PM, <ch...@wbmfg.com> wrote:
>>>
>>> Anyone know how to get my program to run on bare metal?
>>> Or at the very least tell Linux that my program is the most
>>> important thing in the world and service it above all other
>>> things.
>>> I am trying to create a timing signal with the Pi.  It is
>>> doing it but the jitter is pretty bad.
>>> I have researched trying to use an interrupt but there is a
>>> pretty low limit on how many times per second you can fire a
>>> hardware interrupt.
>>> Too low for my application.
>>>
>>
>> --
>>
>
>
>

Re: [AFMUG] OT Raspberry PI

[Chuck McCown]

That looks great.  Did not find a cost anywhere.  

From: Bill Prince 
Sent: Thursday, February 22, 2018 6:47 PM
To: Motorola III 
Subject: Re: [AFMUG] OT Raspberry PI

Try this: http://www.ecoscentric.com/news/press-170314.shtml


--bp


--

bp

part15sbs{at}gmail{dot}com


On Thu, Feb 22, 2018 at 3:56 PM, Bill Prince <part15...@gmail.com> wrote:

  Pretty sure you need  RTOS to accomplish this.That will get pretty close to 
bare metal.


  -bp


  --

  bp

  part15sbs{at}gmail{dot}com


  On Thu, Feb 22, 2018 at 3:36 PM, <ch...@wbmfg.com> wrote:

Had the command syntax wrong.
But got nice to work.  Have to sudo if you use negative nice numbers.

It made zero difference in my jitter.  I went from 19 to –20 on nice and no 
change.  

From: ch...@wbmfg.com 
Sent: Thursday, February 22, 2018 4:29 PM
To: af@afmug.com 
    Subject: Re: [AFMUG] OT Raspberry PI

The problem is there is a crap ton of stuff out there that needs network 
sync.  And it all has a T1 as an input.
But most T1 trunking circuits are getting replaced with SIP.

So, I am building a cheap and dirty T1 signal generator that is GPS and 
rhubidium referenced.  The hard part is easy.  The easy part should be easy but 
all the T1 framing chips that used to exist no longer exist.

The ones that are out there have massive CPU interfaces and tons of 
registers that need to get set to get them fired up and running

Where is Exar when you need them

From: Adam Moffett 
Sent: Thursday, February 22, 2018 4:21 PM
To: af@afmug.com 
    Subject: Re: [AFMUG] OT Raspberry PI

Tell whoever's got the T1 that 1967 is way behind us and get a new 
interface.
Problem eliminated LOL


-- Original Message --
From: ch...@wbmfg.com
To: af@afmug.com
Sent: 2/22/2018 6:16:45 PM
    Subject: Re: [AFMUG] OT Raspberry PI

  I have to generate an alternate mark inversion signal on 1.544 MHz with 
every 193rd bit following a t1 framing sequence.
  Sure wish a 555 could do that.  

  From: Dave 
  Sent: Thursday, February 22, 2018 4:10 PM
  To: af@afmug.com 
      Subject: Re: [AFMUG] OT Raspberry PI

  Find a 555 timer ... I used many in the olden day when radioshacks were 
king LOL!



  On 02/22/2018 05:05 PM, ch...@wbmfg.com wrote:

I am thinking of using some shift registers instead of using the PI 
output directly as the timing signal. 

Use the PI to load them.  

I love me some hardware design anyhow


From: Colin Stanners 
Sent: Thursday, February 22, 2018 3:59 PM
To: af@afmug.com 
    Subject: Re: [AFMUG] OT Raspberry PI

Other than setting the process priority, you may need a custom kernel. 
See 
https://medium.com/@metebalci/latency-of-raspberry-pi-3-on-standard-and-real-time-linux-4-9-kernel-2d9c20704495
 


On Feb 22, 2018 4:48 PM, <ch...@wbmfg.com> wrote:

  Anyone know how to get my program to run on bare metal?

  Or at the very least tell Linux that my program is the most important 
thing in the world and service it above all other things.

  I am trying to create a timing signal with the Pi.  It is doing it 
but the jitter is pretty bad.  

  I have researched trying to use an interrupt but there is a pretty 
low limit on how many times per second you can fire a hardware interrupt.
  Too low for my application.  


  -- 

Re: [AFMUG] OT Raspberry PI

[Bill Prince]

Try this: http://www.ecoscentric.com/news/press-170314.shtml

--bp

--
bp
part15sbs{at}gmail{dot}com

On Thu, Feb 22, 2018 at 3:56 PM, Bill Prince <part15...@gmail.com> wrote:

> Pretty sure you need  RTOS to accomplish this.That will get pretty close
> to bare metal.
>
> -bp
>
> --
> bp
> part15sbs{at}gmail{dot}com
>
> On Thu, Feb 22, 2018 at 3:36 PM, <ch...@wbmfg.com> wrote:
>
>> Had the command syntax wrong.
>> But got nice to work.  Have to sudo if you use negative nice numbers.
>>
>> It made zero difference in my jitter.  I went from 19 to –20 on nice and
>> no change.
>>
>> *From:* ch...@wbmfg.com
>> *Sent:* Thursday, February 22, 2018 4:29 PM
>> *To:* af@afmug.com
>> *Subject:* Re: [AFMUG] OT Raspberry PI
>>
>> The problem is there is a crap ton of stuff out there that needs network
>> sync.  And it all has a T1 as an input.
>> But most T1 trunking circuits are getting replaced with SIP.
>>
>> So, I am building a cheap and dirty T1 signal generator that is GPS and
>> rhubidium referenced.  The hard part is easy.  The easy part should be easy
>> but all the T1 framing chips that used to exist no longer exist.
>>
>> The ones that are out there have massive CPU interfaces and tons of
>> registers that need to get set to get them fired up and running....
>>
>> Where is Exar when you need them
>>
>> *From:* Adam Moffett
>> *Sent:* Thursday, February 22, 2018 4:21 PM
>> *To:* af@afmug.com
>> *Subject:* Re: [AFMUG] OT Raspberry PI
>>
>> Tell whoever's got the T1 that 1967 is way behind us and get a new
>> interface.
>> Problem eliminated LOL
>>
>>
>> -- Original Message --
>> From: ch...@wbmfg.com
>> To: af@afmug.com
>> Sent: 2/22/2018 6:16:45 PM
>> Subject: Re: [AFMUG] OT Raspberry PI
>>
>>
>> I have to generate an alternate mark inversion signal on 1.544 MHz with
>> every 193rd bit following a t1 framing sequence.
>> Sure wish a 555 could do that.
>>
>> *From:* Dave
>> *Sent:* Thursday, February 22, 2018 4:10 PM
>> *To:* af@afmug.com
>> *Subject:* Re: [AFMUG] OT Raspberry PI
>>
>> Find a 555 timer ... I used many in the olden day when radioshacks were
>> king LOL!
>>
>>
>> On 02/22/2018 05:05 PM, ch...@wbmfg.com wrote:
>>
>> I am thinking of using some shift registers instead of using the PI
>> output directly as the timing signal.
>>
>> Use the PI to load them.
>>
>> I love me some hardware design anyhow
>>
>>
>> *From:* Colin Stanners
>> *Sent:* Thursday, February 22, 2018 3:59 PM
>> *To:* af@afmug.com
>> *Subject:* Re: [AFMUG] OT Raspberry PI
>>
>> Other than setting the process priority, you may need a custom kernel.
>> See https://medium.com/@metebalci/latency-of-raspberry-pi-3-on-s
>> tandard-and-real-time-linux-4-9-kernel-2d9c20704495
>>
>>
>> On Feb 22, 2018 4:48 PM, <ch...@wbmfg.com> wrote:
>>
>>> Anyone know how to get my program to run on bare metal?
>>>
>>> Or at the very least tell Linux that my program is the most important
>>> thing in the world and service it above all other things.
>>>
>>> I am trying to create a timing signal with the Pi.  It is doing it but
>>> the jitter is pretty bad.
>>>
>>> I have researched trying to use an interrupt but there is a pretty low
>>> limit on how many times per second you can fire a hardware interrupt.
>>> Too low for my application.
>>>
>>
>> --
>>
>>
>

Re: [AFMUG] OT Raspberry PI

[Lewis Bergman]

They aren't cheap but you could always use an fpga.

On Thu, Feb 22, 2018, 7:35 PM Chuck McCown <ch...@wbmfg.com> wrote:

> No, I saw it, but I already had the Pi so I ignored it and hoped for the
> best.
> I tried it first with arduino.  Just not enough speed.  And it had the
> jitter problem too.
>
> I have a method using three TTL/CMOS chips that is going to work... I
> think...
>
> The only thing separating the gps disciplined signal and the T1 will be a
> D flip flop and a few AND/NAND gates.  So that ought to get me super low
> jitter.
>
> Trying for stratum I with rubidium hold-over isochronous performance at
> the end of the day.  For cheap.
>
> *From:* Forrest Christian (List Account)
> *Sent:* Thursday, February 22, 2018 6:27 PM
> *To:* af
> *Subject:* Re: [AFMUG] OT Raspberry PI
>
> Ok, I think you missed this portion of my email last time:
>
>
> *"I'm skeptical that you'll be able to generate a bitstream with enough
> accuracy under Linux, without extreme programming measures.I'd suggest a
> digilent chipkit wifire and the arduino ide for this.  You should be able
> to bitbang at least a T1 with this processor (500mhz)"*
>
> Generally the raspberry pi is great for 'tiny server stuff', or 'user
> interface' stuff, and the arduino and/or microcontrollers will work better
> for what you're looking at, since there isn't an operating system in the
> way.  All arduino really is is a c++ ide with some simplified libraries.
>
> The wifire product I mentioned is really a PIC32MZ dev board, optimized
> for arduino.  If you've had enough of the arduino ide, you can download the
> microchip ide and program it with a full development kit.
>
> Honestly for what you are talking about a EUSART in even a low end PIC
> might be able to handle this.  If you program the EUSART into synchronous
> mode you'll just have to stuff a byte into it every 8 bit times and it will
> clock it out for you.  Not sure if the clock rate is adjustable enough for
> you, but if you get a PIC with the NCO peripheral you might be able to
> dynamically adjust the frequency enough to make it work.
>
> NCO app sheet:
> http://ww1.microchip.com/downloads/en/AppNotes/90003131A.pdf
>
>
>
>
> On Thu, Feb 22, 2018 at 3:48 PM, <ch...@wbmfg.com> wrote:
>
>> Anyone know how to get my program to run on bare metal?
>>
>> Or at the very least tell Linux that my program is the most important
>> thing in the world and service it above all other things.
>>
>> I am trying to create a timing signal with the Pi.  It is doing it but
>> the jitter is pretty bad.
>>
>> I have researched trying to use an interrupt but there is a pretty low
>> limit on how many times per second you can fire a hardware interrupt.
>> Too low for my application.
>>
>
>
>
> --
> *Forrest Christian* *CEO**, PacketFlux Technologies, Inc.*
> Tel: 406-449-3345 | Address: 3577 Countryside Road, Helena, MT 59602
> <https://maps.google.com/?q=3577+Countryside+Road,+Helena,+MT+%0D+59602=gmail=g>
> forre...@imach.com | http://www.packetflux.com
> <http://www.linkedin.com/in/fwchristian>  <http://facebook.com/packetflux>
>   <http://twitter.com/@packetflux>
>
>

Re: [AFMUG] OT Raspberry PI

[Chuck McCown]

No, I saw it, but I already had the Pi so I ignored it and hoped for the best.
I tried it first with arduino.  Just not enough speed.  And it had the jitter 
problem too.

I have a method using three TTL/CMOS chips that is going to work... I think...

The only thing separating the gps disciplined signal and the T1 will be a D 
flip flop and a few AND/NAND gates.  So that ought to get me super low jitter.  

Trying for stratum I with rubidium hold-over isochronous performance at the end 
of the day.  For cheap.

From: Forrest Christian (List Account) 
Sent: Thursday, February 22, 2018 6:27 PM
To: af 
Subject: Re: [AFMUG] OT Raspberry PI

Ok, I think you missed this portion of my email last time:

"I'm skeptical that you'll be able to generate a bitstream with enough accuracy 
under Linux, without extreme programming measures.
I'd suggest a digilent chipkit wifire and the arduino ide for this.  You should 
be able to bitbang at least a T1 with this processor (500mhz)"

Generally the raspberry pi is great for 'tiny server stuff', or 'user 
interface' stuff, and the arduino and/or microcontrollers will work better for 
what you're looking at, since there isn't an operating system in the way.  All 
arduino really is is a c++ ide with some simplified libraries. 

The wifire product I mentioned is really a PIC32MZ dev board, optimized for 
arduino.  If you've had enough of the arduino ide, you can download the 
microchip ide and program it with a full development kit.


Honestly for what you are talking about a EUSART in even a low end PIC might be 
able to handle this.  If you program the EUSART into synchronous mode you'll 
just have to stuff a byte into it every 8 bit times and it will clock it out 
for you.  Not sure if the clock rate is adjustable enough for you, but if you 
get a PIC with the NCO peripheral you might be able to dynamically adjust the 
frequency enough to make it work. 

NCO app sheet:  http://ww1.microchip.com/downloads/en/AppNotes/90003131A.pdf




On Thu, Feb 22, 2018 at 3:48 PM, <ch...@wbmfg.com> wrote:

  Anyone know how to get my program to run on bare metal?

  Or at the very least tell Linux that my program is the most important thing 
in the world and service it above all other things.

  I am trying to create a timing signal with the Pi.  It is doing it but the 
jitter is pretty bad.  

  I have researched trying to use an interrupt but there is a pretty low limit 
on how many times per second you can fire a hardware interrupt.
  Too low for my application.  




-- 

  Forrest Christian CEO, PacketFlux Technologies, Inc.

  Tel: 406-449-3345 | Address: 3577 Countryside Road, Helena, MT 59602
  forre...@imach.com | http://www.packetflux.com

 

Re: [AFMUG] OT Raspberry PI

[Forrest Christian (List Account)]

Ok, I think you missed this portion of my email last time:


*"I'm skeptical that you'll be able to generate a bitstream with enough
accuracy under Linux, without extreme programming measures.I'd suggest a
digilent chipkit wifire and the arduino ide for this.  You should be able
to bitbang at least a T1 with this processor (500mhz)"*

Generally the raspberry pi is great for 'tiny server stuff', or 'user
interface' stuff, and the arduino and/or microcontrollers will work better
for what you're looking at, since there isn't an operating system in the
way.  All arduino really is is a c++ ide with some simplified libraries.

The wifire product I mentioned is really a PIC32MZ dev board, optimized for
arduino.  If you've had enough of the arduino ide, you can download the
microchip ide and program it with a full development kit.

Honestly for what you are talking about a EUSART in even a low end PIC
might be able to handle this.  If you program the EUSART into synchronous
mode you'll just have to stuff a byte into it every 8 bit times and it will
clock it out for you.  Not sure if the clock rate is adjustable enough for
you, but if you get a PIC with the NCO peripheral you might be able to
dynamically adjust the frequency enough to make it work.

NCO app sheet:  http://ww1.microchip.com/downloads/en/AppNotes/90003131A.pdf




On Thu, Feb 22, 2018 at 3:48 PM,  wrote:

> Anyone know how to get my program to run on bare metal?
>
> Or at the very least tell Linux that my program is the most important
> thing in the world and service it above all other things.
>
> I am trying to create a timing signal with the Pi.  It is doing it but the
> jitter is pretty bad.
>
> I have researched trying to use an interrupt but there is a pretty low
> limit on how many times per second you can fire a hardware interrupt.
> Too low for my application.
>



-- 
*Forrest Christian* *CEO**, PacketFlux Technologies, Inc.*
Tel: 406-449-3345 | Address: 3577 Countryside Road, Helena, MT 59602
forre...@imach.com | http://www.packetflux.com
  

Re: [AFMUG] OT Raspberry PI

[Chuck McCown]

It has keyboard, usb, hdmi, wifi, ethernet and other processes.  But 
apparently prioritizing my program above them really does not affect how 
often it visits my program.


I have about 250 nS of jitter on my output signal.

-Original Message- 
From: Seth Mattinen

Sent: Thursday, February 22, 2018 5:58 PM
To: af@afmug.com
Subject: Re: [AFMUG] OT Raspberry PI

On 2/22/18 3:36 PM, ch...@wbmfg.com wrote:

Had the command syntax wrong.
But got nice to work.  Have to sudo if you use negative nice numbers.
It made zero difference in my jitter.  I went from 19 to –20 on nice and 
no change.



nice really only helps prioritize (or not) compared to other running
processes. 

Re: [AFMUG] OT Raspberry PI

[Lewis Bergman]

Pi is not that fast when you talk about the gpio. While trying to measure
some ac signals i was amazed i could only measure 4 inputs and still get a
resolution of .5 amps on each one.

On Thu, Feb 22, 2018, 6:59 PM Seth Mattinen  wrote:

> On 2/22/18 3:36 PM, ch...@wbmfg.com wrote:
> > Had the command syntax wrong.
> > But got nice to work.  Have to sudo if you use negative nice numbers.
> > It made zero difference in my jitter.  I went from 19 to –20 on nice and
> > no change.
>
>
> nice really only helps prioritize (or not) compared to other running
> processes.
>

Re: [AFMUG] OT Raspberry PI

[Seth Mattinen]

On 2/22/18 3:36 PM, ch...@wbmfg.com wrote:

Had the command syntax wrong.
But got nice to work.  Have to sudo if you use negative nice numbers.
It made zero difference in my jitter.  I went from 19 to –20 on nice and 
no change.



nice really only helps prioritize (or not) compared to other running 
processes.

Re: [AFMUG] OT Raspberry PI

[Robert]

I believe this was a major part of the improvements in android

On 2/22/18 3:58 PM, Bill Prince wrote:
Pretty sure you need  RTOS to accomplish this.That will get pretty close 
to bare metal.


-bp

--
bp
part15sbs{at}gmail{dot}com

On Thu, Feb 22, 2018 at 3:36 PM, <ch...@wbmfg.com 
<mailto:ch...@wbmfg.com>> wrote:


Had the command syntax wrong.
But got nice to work.  Have to sudo if you use negative nice numbers.
It made zero difference in my jitter.  I went from 19 to –20 on nice
and no change.
*From:* ch...@wbmfg.com
*Sent:* Thursday, February 22, 2018 4:29 PM
*To:* af@afmug.com
    *Subject:* Re: [AFMUG] OT Raspberry PI
The problem is there is a crap ton of stuff out there that needs
network sync.  And it all has a T1 as an input.
But most T1 trunking circuits are getting replaced with SIP.
So, I am building a cheap and dirty T1 signal generator that is GPS
and rhubidium referenced.  The hard part is easy.  The easy part
should be easy but all the T1 framing chips that used to exist no
longer exist.
The ones that are out there have massive CPU interfaces and tons of
registers that need to get set to get them fired up and running
Where is Exar when you need them
*From:* Adam Moffett
*Sent:* Thursday, February 22, 2018 4:21 PM
*To:* af@afmug.com
    *Subject:* Re: [AFMUG] OT Raspberry PI
Tell whoever's got the T1 that 1967 is way behind us and get a new
interface.
Problem eliminated LOL
-- Original Message --
From: ch...@wbmfg.com
To: af@afmug.com
Sent: 2/22/2018 6:16:45 PM
    Subject: Re: [AFMUG] OT Raspberry PI

I have to generate an alternate mark inversion signal on 1.544 MHz
with every 193rd bit following a t1 framing sequence.
Sure wish a 555 could do that.
*From:* Dave
*Sent:* Thursday, February 22, 2018 4:10 PM
*To:* af@afmug.com
    *Subject:* Re: [AFMUG] OT Raspberry PI
Find a 555 timer ... I used many in the olden day when radioshacks
were king LOL!


On 02/22/2018 05:05 PM, ch...@wbmfg.com wrote:

I am thinking of using some shift registers instead of using the
PI output directly as the timing signal.
Use the PI to load them.
I love me some hardware design anyhow
*From:* Colin Stanners
*Sent:* Thursday, February 22, 2018 3:59 PM
*To:* af@afmug.com
    *Subject:* Re: [AFMUG] OT Raspberry PI
Other than setting the process priority, you may need a custom
kernel. See

https://medium.com/@metebalci/latency-of-raspberry-pi-3-on-standard-and-real-time-linux-4-9-kernel-2d9c20704495

<https://medium.com/@metebalci/latency-of-raspberry-pi-3-on-standard-and-real-time-linux-4-9-kernel-2d9c20704495>

On Feb 22, 2018 4:48 PM, <ch...@wbmfg.com> wrote:

Anyone know how to get my program to run on bare metal?
Or at the very least tell Linux that my program is the most
important thing in the world and service it above all other
things.
I am trying to create a timing signal with the Pi.  It is
doing it but the jitter is pretty bad.
I have researched trying to use an interrupt but there is a
pretty low limit on how many times per second you can fire a
hardware interrupt.
Too low for my application. 


-- 

Re: [AFMUG] OT Raspberry PI

[chuck]

How much?

From: Colin Stanners 
Sent: Thursday, February 22, 2018 5:21 PM
To: af@afmug.com 
Subject: Re: [AFMUG] OT Raspberry PI

I found these devices that do what you want, but they look fancy and expensive, 
I'm guessing that you wish to get around the latter.

https://www.engageinc.com/products/tdm/prima-stratum-gps-stratum-1-clock.html   
 https://www.endruntechnologies.com/gps-frequency-standard.htm


On Thu, Feb 22, 2018 at 5:29 PM, <ch...@wbmfg.com> wrote:

  The problem is there is a crap ton of stuff out there that needs network 
sync.  And it all has a T1 as an input.
  But most T1 trunking circuits are getting replaced with SIP.

  So, I am building a cheap and dirty T1 signal generator that is GPS and 
rhubidium referenced.  The hard part is easy.  The easy part should be easy but 
all the T1 framing chips that used to exist no longer exist.

  The ones that are out there have massive CPU interfaces and tons of registers 
that need to get set to get them fired up and running

  Where is Exar when you need them

  From: Adam Moffett 
  Sent: Thursday, February 22, 2018 4:21 PM
  To: af@afmug.com 
  Subject: Re: [AFMUG] OT Raspberry PI

  Tell whoever's got the T1 that 1967 is way behind us and get a new interface.
  Problem eliminated LOL


  -- Original Message --
  From: ch...@wbmfg.com
  To: af@afmug.com
  Sent: 2/22/2018 6:16:45 PM
  Subject: Re: [AFMUG] OT Raspberry PI

I have to generate an alternate mark inversion signal on 1.544 MHz with 
every 193rd bit following a t1 framing sequence.
Sure wish a 555 could do that.  

From: Dave 
Sent: Thursday, February 22, 2018 4:10 PM
To: af@afmug.com 
Subject: Re: [AFMUG] OT Raspberry PI

Find a 555 timer ... I used many in the olden day when radioshacks were 
king LOL!



On 02/22/2018 05:05 PM, ch...@wbmfg.com wrote:

  I am thinking of using some shift registers instead of using the PI 
output directly as the timing signal. 

  Use the PI to load them.  

  I love me some hardware design anyhow


  From: Colin Stanners 
  Sent: Thursday, February 22, 2018 3:59 PM
  To: af@afmug.com 
  Subject: Re: [AFMUG] OT Raspberry PI

  Other than setting the process priority, you may need a custom kernel. 
See 
https://medium.com/@metebalci/latency-of-raspberry-pi-3-on-standard-and-real-time-linux-4-9-kernel-2d9c20704495
 


  On Feb 22, 2018 4:48 PM, <ch...@wbmfg.com> wrote:

Anyone know how to get my program to run on bare metal?

Or at the very least tell Linux that my program is the most important 
thing in the world and service it above all other things.

I am trying to create a timing signal with the Pi.  It is doing it but 
the jitter is pretty bad.  

I have researched trying to use an interrupt but there is a pretty low 
limit on how many times per second you can fire a hardware interrupt.
Too low for my application.  


-- 

Re: [AFMUG] OT Raspberry PI

[Colin Stanners]

I found these devices that do what you want, but they look fancy and
expensive, I'm guessing that you wish to get around the latter.

https://www.engageinc.com/products/tdm/prima-stratum-gps-stratum-1-clock.html
   https://www.endruntechnologies.com/gps-frequency-standard.htm

On Thu, Feb 22, 2018 at 5:29 PM, <ch...@wbmfg.com> wrote:

> The problem is there is a crap ton of stuff out there that needs network
> sync.  And it all has a T1 as an input.
> But most T1 trunking circuits are getting replaced with SIP.
>
> So, I am building a cheap and dirty T1 signal generator that is GPS and
> rhubidium referenced.  The hard part is easy.  The easy part should be easy
> but all the T1 framing chips that used to exist no longer exist.
>
> The ones that are out there have massive CPU interfaces and tons of
> registers that need to get set to get them fired up and running
>
> Where is Exar when you need them
>
> *From:* Adam Moffett
> *Sent:* Thursday, February 22, 2018 4:21 PM
> *To:* af@afmug.com
> *Subject:* Re: [AFMUG] OT Raspberry PI
>
> Tell whoever's got the T1 that 1967 is way behind us and get a new
> interface.
> Problem eliminated LOL
>
>
> -- Original Message --
> From: ch...@wbmfg.com
> To: af@afmug.com
> Sent: 2/22/2018 6:16:45 PM
> Subject: Re: [AFMUG] OT Raspberry PI
>
>
> I have to generate an alternate mark inversion signal on 1.544 MHz with
> every 193rd bit following a t1 framing sequence.
> Sure wish a 555 could do that.
>
> *From:* Dave
> *Sent:* Thursday, February 22, 2018 4:10 PM
> *To:* af@afmug.com
> *Subject:* Re: [AFMUG] OT Raspberry PI
>
> Find a 555 timer ... I used many in the olden day when radioshacks were
> king LOL!
>
>
> On 02/22/2018 05:05 PM, ch...@wbmfg.com wrote:
>
> I am thinking of using some shift registers instead of using the PI output
> directly as the timing signal.
>
> Use the PI to load them.
>
> I love me some hardware design anyhow
>
>
> *From:* Colin Stanners
> *Sent:* Thursday, February 22, 2018 3:59 PM
> *To:* af@afmug.com
> *Subject:* Re: [AFMUG] OT Raspberry PI
>
> Other than setting the process priority, you may need a custom kernel. See
> https://medium.com/@metebalci/latency-of-raspberry-pi-3-on-
> standard-and-real-time-linux-4-9-kernel-2d9c20704495
>
>
> On Feb 22, 2018 4:48 PM, <ch...@wbmfg.com> wrote:
>
>> Anyone know how to get my program to run on bare metal?
>>
>> Or at the very least tell Linux that my program is the most important
>> thing in the world and service it above all other things.
>>
>> I am trying to create a timing signal with the Pi.  It is doing it but
>> the jitter is pretty bad.
>>
>> I have researched trying to use an interrupt but there is a pretty low
>> limit on how many times per second you can fire a hardware interrupt.
>> Too low for my application.
>>
>
> --
>
>

Re: [AFMUG] OT Raspberry PI

[chuck]

I am switching to a d flip flop and some and/nand gates.
I’ll bet I have not purchased a gate chip for >20 years.  

This way I will only have to do an output from the Pi ever 193 cycles.  

I can count clocks and then assert the correct output for that one cycle.  

The rest of the time the D flip flop will be just repeating the GPS.  

Once I get this working I am going back to the arduino to see if it is fast 
enough to take the place of the PI.  

Or, maybe I will go D flip flop crazy and do the whole thing in a finite state 
machine...

From: Bill Prince 
Sent: Thursday, February 22, 2018 4:58 PM
To: Motorola III 
Subject: Re: [AFMUG] OT Raspberry PI

Pretty sure you need  RTOS to accomplish this.That will get pretty close to 
bare metal.


-bp


--

bp

part15sbs{at}gmail{dot}com


On Thu, Feb 22, 2018 at 3:36 PM, <ch...@wbmfg.com> wrote:

  Had the command syntax wrong.
  But got nice to work.  Have to sudo if you use negative nice numbers.

  It made zero difference in my jitter.  I went from 19 to –20 on nice and no 
change.  

  From: ch...@wbmfg.com 
  Sent: Thursday, February 22, 2018 4:29 PM
  To: af@afmug.com 
  Subject: Re: [AFMUG] OT Raspberry PI

  The problem is there is a crap ton of stuff out there that needs network 
sync.  And it all has a T1 as an input.
  But most T1 trunking circuits are getting replaced with SIP.

  So, I am building a cheap and dirty T1 signal generator that is GPS and 
rhubidium referenced.  The hard part is easy.  The easy part should be easy but 
all the T1 framing chips that used to exist no longer exist.

  The ones that are out there have massive CPU interfaces and tons of registers 
that need to get set to get them fired up and running

  Where is Exar when you need them

  From: Adam Moffett 
  Sent: Thursday, February 22, 2018 4:21 PM
  To: af@afmug.com 
  Subject: Re: [AFMUG] OT Raspberry PI

  Tell whoever's got the T1 that 1967 is way behind us and get a new interface.
  Problem eliminated LOL


  -- Original Message --
  From: ch...@wbmfg.com
  To: af@afmug.com
  Sent: 2/22/2018 6:16:45 PM
  Subject: Re: [AFMUG] OT Raspberry PI

I have to generate an alternate mark inversion signal on 1.544 MHz with 
every 193rd bit following a t1 framing sequence.
Sure wish a 555 could do that.  

From: Dave 
Sent: Thursday, February 22, 2018 4:10 PM
To: af@afmug.com 
Subject: Re: [AFMUG] OT Raspberry PI

Find a 555 timer ... I used many in the olden day when radioshacks were 
king LOL!



On 02/22/2018 05:05 PM, ch...@wbmfg.com wrote:

  I am thinking of using some shift registers instead of using the PI 
output directly as the timing signal. 

  Use the PI to load them.  

  I love me some hardware design anyhow


  From: Colin Stanners 
  Sent: Thursday, February 22, 2018 3:59 PM
  To: af@afmug.com 
  Subject: Re: [AFMUG] OT Raspberry PI

  Other than setting the process priority, you may need a custom kernel. 
See 
https://medium.com/@metebalci/latency-of-raspberry-pi-3-on-standard-and-real-time-linux-4-9-kernel-2d9c20704495
 


  On Feb 22, 2018 4:48 PM, <ch...@wbmfg.com> wrote:

Anyone know how to get my program to run on bare metal?

Or at the very least tell Linux that my program is the most important 
thing in the world and service it above all other things.

I am trying to create a timing signal with the Pi.  It is doing it but 
the jitter is pretty bad.  

I have researched trying to use an interrupt but there is a pretty low 
limit on how many times per second you can fire a hardware interrupt.
Too low for my application.  


-- 

Re: [AFMUG] OT Raspberry PI

[Bill Prince]

Pretty sure you need  RTOS to accomplish this.That will get pretty close to
bare metal.

-bp

--
bp
part15sbs{at}gmail{dot}com

On Thu, Feb 22, 2018 at 3:36 PM, <ch...@wbmfg.com> wrote:

> Had the command syntax wrong.
> But got nice to work.  Have to sudo if you use negative nice numbers.
>
> It made zero difference in my jitter.  I went from 19 to –20 on nice and
> no change.
>
> *From:* ch...@wbmfg.com
> *Sent:* Thursday, February 22, 2018 4:29 PM
> *To:* af@afmug.com
> *Subject:* Re: [AFMUG] OT Raspberry PI
>
> The problem is there is a crap ton of stuff out there that needs network
> sync.  And it all has a T1 as an input.
> But most T1 trunking circuits are getting replaced with SIP.
>
> So, I am building a cheap and dirty T1 signal generator that is GPS and
> rhubidium referenced.  The hard part is easy.  The easy part should be easy
> but all the T1 framing chips that used to exist no longer exist.
>
> The ones that are out there have massive CPU interfaces and tons of
> registers that need to get set to get them fired up and running
>
> Where is Exar when you need them
>
> *From:* Adam Moffett
> *Sent:* Thursday, February 22, 2018 4:21 PM
> *To:* af@afmug.com
> *Subject:* Re: [AFMUG] OT Raspberry PI
>
> Tell whoever's got the T1 that 1967 is way behind us and get a new
> interface.
> Problem eliminated LOL
>
>
> ------ Original Message ------
> From: ch...@wbmfg.com
> To: af@afmug.com
> Sent: 2/22/2018 6:16:45 PM
> Subject: Re: [AFMUG] OT Raspberry PI
>
>
> I have to generate an alternate mark inversion signal on 1.544 MHz with
> every 193rd bit following a t1 framing sequence.
> Sure wish a 555 could do that.
>
> *From:* Dave
> *Sent:* Thursday, February 22, 2018 4:10 PM
> *To:* af@afmug.com
> *Subject:* Re: [AFMUG] OT Raspberry PI
>
> Find a 555 timer ... I used many in the olden day when radioshacks were
> king LOL!
>
>
> On 02/22/2018 05:05 PM, ch...@wbmfg.com wrote:
>
> I am thinking of using some shift registers instead of using the PI output
> directly as the timing signal.
>
> Use the PI to load them.
>
> I love me some hardware design anyhow
>
>
> *From:* Colin Stanners
> *Sent:* Thursday, February 22, 2018 3:59 PM
> *To:* af@afmug.com
> *Subject:* Re: [AFMUG] OT Raspberry PI
>
> Other than setting the process priority, you may need a custom kernel. See
> https://medium.com/@metebalci/latency-of-raspberry-pi-3-on-
> standard-and-real-time-linux-4-9-kernel-2d9c20704495
>
>
> On Feb 22, 2018 4:48 PM, <ch...@wbmfg.com> wrote:
>
>> Anyone know how to get my program to run on bare metal?
>>
>> Or at the very least tell Linux that my program is the most important
>> thing in the world and service it above all other things.
>>
>> I am trying to create a timing signal with the Pi.  It is doing it but
>> the jitter is pretty bad.
>>
>> I have researched trying to use an interrupt but there is a pretty low
>> limit on how many times per second you can fire a hardware interrupt.
>> Too low for my application.
>>
>
> --
>
>

Re: [AFMUG] OT Raspberry PI

[chuck]

Had the command syntax wrong.
But got nice to work.  Have to sudo if you use negative nice numbers.

It made zero difference in my jitter.  I went from 19 to –20 on nice and no 
change.  

From: ch...@wbmfg.com 
Sent: Thursday, February 22, 2018 4:29 PM
To: af@afmug.com 
Subject: Re: [AFMUG] OT Raspberry PI

The problem is there is a crap ton of stuff out there that needs network sync.  
And it all has a T1 as an input.
But most T1 trunking circuits are getting replaced with SIP.

So, I am building a cheap and dirty T1 signal generator that is GPS and 
rhubidium referenced.  The hard part is easy.  The easy part should be easy but 
all the T1 framing chips that used to exist no longer exist.

The ones that are out there have massive CPU interfaces and tons of registers 
that need to get set to get them fired up and running

Where is Exar when you need them

From: Adam Moffett 
Sent: Thursday, February 22, 2018 4:21 PM
To: af@afmug.com 
Subject: Re: [AFMUG] OT Raspberry PI

Tell whoever's got the T1 that 1967 is way behind us and get a new interface.
Problem eliminated LOL


-- Original Message --
From: ch...@wbmfg.com
To: af@afmug.com
Sent: 2/22/2018 6:16:45 PM
Subject: Re: [AFMUG] OT Raspberry PI

  I have to generate an alternate mark inversion signal on 1.544 MHz with every 
193rd bit following a t1 framing sequence.
  Sure wish a 555 could do that.  

  From: Dave 
  Sent: Thursday, February 22, 2018 4:10 PM
  To: af@afmug.com 
  Subject: Re: [AFMUG] OT Raspberry PI

  Find a 555 timer ... I used many in the olden day when radioshacks were king 
LOL!



  On 02/22/2018 05:05 PM, ch...@wbmfg.com wrote:

I am thinking of using some shift registers instead of using the PI output 
directly as the timing signal. 

Use the PI to load them.  

I love me some hardware design anyhow


From: Colin Stanners 
Sent: Thursday, February 22, 2018 3:59 PM
To: af@afmug.com 
Subject: Re: [AFMUG] OT Raspberry PI

Other than setting the process priority, you may need a custom kernel. See 
https://medium.com/@metebalci/latency-of-raspberry-pi-3-on-standard-and-real-time-linux-4-9-kernel-2d9c20704495
 


On Feb 22, 2018 4:48 PM, <ch...@wbmfg.com> wrote:

  Anyone know how to get my program to run on bare metal?

  Or at the very least tell Linux that my program is the most important 
thing in the world and service it above all other things.

  I am trying to create a timing signal with the Pi.  It is doing it but 
the jitter is pretty bad.  

  I have researched trying to use an interrupt but there is a pretty low 
limit on how many times per second you can fire a hardware interrupt.
  Too low for my application.  


  -- 

Re: [AFMUG] OT Raspberry PI

[chuck]

The problem is there is a crap ton of stuff out there that needs network sync.  
And it all has a T1 as an input.
But most T1 trunking circuits are getting replaced with SIP.

So, I am building a cheap and dirty T1 signal generator that is GPS and 
rhubidium referenced.  The hard part is easy.  The easy part should be easy but 
all the T1 framing chips that used to exist no longer exist.

The ones that are out there have massive CPU interfaces and tons of registers 
that need to get set to get them fired up and running

Where is Exar when you need them

From: Adam Moffett 
Sent: Thursday, February 22, 2018 4:21 PM
To: af@afmug.com 
Subject: Re: [AFMUG] OT Raspberry PI

Tell whoever's got the T1 that 1967 is way behind us and get a new interface.
Problem eliminated LOL


-- Original Message --
From: ch...@wbmfg.com
To: af@afmug.com
Sent: 2/22/2018 6:16:45 PM
Subject: Re: [AFMUG] OT Raspberry PI

  I have to generate an alternate mark inversion signal on 1.544 MHz with every 
193rd bit following a t1 framing sequence.
  Sure wish a 555 could do that.  

  From: Dave 
  Sent: Thursday, February 22, 2018 4:10 PM
  To: af@afmug.com 
  Subject: Re: [AFMUG] OT Raspberry PI

  Find a 555 timer ... I used many in the olden day when radioshacks were king 
LOL!



  On 02/22/2018 05:05 PM, ch...@wbmfg.com wrote:

I am thinking of using some shift registers instead of using the PI output 
directly as the timing signal. 

Use the PI to load them.  

I love me some hardware design anyhow


From: Colin Stanners 
Sent: Thursday, February 22, 2018 3:59 PM
To: af@afmug.com 
Subject: Re: [AFMUG] OT Raspberry PI

Other than setting the process priority, you may need a custom kernel. See 
https://medium.com/@metebalci/latency-of-raspberry-pi-3-on-standard-and-real-time-linux-4-9-kernel-2d9c20704495
 


On Feb 22, 2018 4:48 PM, <ch...@wbmfg.com> wrote:

  Anyone know how to get my program to run on bare metal?

  Or at the very least tell Linux that my program is the most important 
thing in the world and service it above all other things.

  I am trying to create a timing signal with the Pi.  It is doing it but 
the jitter is pretty bad.  

  I have researched trying to use an interrupt but there is a pretty low 
limit on how many times per second you can fire a hardware interrupt.
  Too low for my application.  


  -- 

Re: [AFMUG] OT Raspberry PI

[chuck]

C

I just ran

nice ./blink -20

and it did not seem to change the jitter at all.

-Original Message- 
From: Josh Reynolds

Sent: Thursday, February 22, 2018 4:19 PM
To: af@afmug.com
Subject: Re: [AFMUG] OT Raspberry PI

Well, first of all what is your program written in?

On Thu, Feb 22, 2018 at 4:48 PM,  <ch...@wbmfg.com> wrote:

Anyone know how to get my program to run on bare metal?

Or at the very least tell Linux that my program is the most important 
thing

in the world and service it above all other things.

I am trying to create a timing signal with the Pi.  It is doing it but the
jitter is pretty bad.

I have researched trying to use an interrupt but there is a pretty low 
limit

on how many times per second you can fire a hardware interrupt.
Too low for my application. 

Re: [AFMUG] OT Raspberry PI

[Adam Moffett]

Tell whoever's got the T1 that 1967 is way behind us and get a new 
interface.

Problem eliminated LOL


-- Original Message --
From: ch...@wbmfg.com
To: af@afmug.com
Sent: 2/22/2018 6:16:45 PM
Subject: Re: [AFMUG] OT Raspberry PI

I have to generate an alternate mark inversion signal on 1.544 MHz with 
every 193rd bit following a t1 framing sequence.

Sure wish a 555 could do that.

From:Dave
Sent: Thursday, February 22, 2018 4:10 PM
To:af@afmug.com
Subject: Re: [AFMUG] OT Raspberry PI

Find a 555 timer ... I used many in the olden day when radioshacks were 
king LOL!



On 02/22/2018 05:05 PM, ch...@wbmfg.com wrote:
I am thinking of using some shift registers instead of using the PI 
output directly as the timing signal.


Use the PI to load them.

I love me some hardware design anyhow


From:Colin Stanners
Sent: Thursday, February 22, 2018 3:59 PM
To:af@afmug.com
Subject: Re: [AFMUG] OT Raspberry PI

Other than setting the process priority, you may need a custom kernel. 
See 
https://medium.com/@metebalci/latency-of-raspberry-pi-3-on-standard-and-real-time-linux-4-9-kernel-2d9c20704495



On Feb 22, 2018 4:48 PM, <ch...@wbmfg.com> wrote:

Anyone know how to get my program to run on bare metal?

Or at the very least tell Linux that my program is the most important 
thing in the world and service it above all other things.


I am trying to create a timing signal with the Pi.  It is doing it 
but the jitter is pretty bad.


I have researched trying to use an interrupt but there is a pretty 
low limit on how many times per second you can fire a hardware 
interrupt.

Too low for my application.


--

Re: [AFMUG] OT Raspberry PI

[Josh Reynolds]

Well, first of all what is your program written in?

On Thu, Feb 22, 2018 at 4:48 PM,   wrote:
> Anyone know how to get my program to run on bare metal?
>
> Or at the very least tell Linux that my program is the most important thing
> in the world and service it above all other things.
>
> I am trying to create a timing signal with the Pi.  It is doing it but the
> jitter is pretty bad.
>
> I have researched trying to use an interrupt but there is a pretty low limit
> on how many times per second you can fire a hardware interrupt.
> Too low for my application.

Re: [AFMUG] OT Raspberry PI

[chuck]

I have to generate an alternate mark inversion signal on 1.544 MHz with every 
193rd bit following a t1 framing sequence.
Sure wish a 555 could do that.  

From: Dave 
Sent: Thursday, February 22, 2018 4:10 PM
To: af@afmug.com 
Subject: Re: [AFMUG] OT Raspberry PI

Find a 555 timer ... I used many in the olden day when radioshacks were king 
LOL!



On 02/22/2018 05:05 PM, ch...@wbmfg.com wrote:

  I am thinking of using some shift registers instead of using the PI output 
directly as the timing signal. 

  Use the PI to load them.  

  I love me some hardware design anyhow


  From: Colin Stanners 
  Sent: Thursday, February 22, 2018 3:59 PM
  To: af@afmug.com 
  Subject: Re: [AFMUG] OT Raspberry PI

  Other than setting the process priority, you may need a custom kernel. See 
https://medium.com/@metebalci/latency-of-raspberry-pi-3-on-standard-and-real-time-linux-4-9-kernel-2d9c20704495
 


  On Feb 22, 2018 4:48 PM, <ch...@wbmfg.com> wrote:

Anyone know how to get my program to run on bare metal?

Or at the very least tell Linux that my program is the most important thing 
in the world and service it above all other things.

I am trying to create a timing signal with the Pi.  It is doing it but the 
jitter is pretty bad.  

I have researched trying to use an interrupt but there is a pretty low 
limit on how many times per second you can fire a hardware interrupt.
Too low for my application.  


-- 

Re: [AFMUG] OT Raspberry PI

[Dave]

Find a 555 timer ... I used many in the olden day when radioshacks were 
king LOL!



On 02/22/2018 05:05 PM, ch...@wbmfg.com wrote:
I am thinking of using some shift registers instead of using the PI 
output directly as the timing signal.

Use the PI to load them.
I love me some hardware design anyhow
*From:* Colin Stanners
*Sent:* Thursday, February 22, 2018 3:59 PM
*To:* af@afmug.com
*Subject:* Re: [AFMUG] OT Raspberry PI
Other than setting the process priority, you may need a custom kernel. 
See 
https://medium.com/@metebalci/latency-of-raspberry-pi-3-on-standard-and-real-time-linux-4-9-kernel-2d9c20704495 


On Feb 22, 2018 4:48 PM, <ch...@wbmfg.com> wrote:

Anyone know how to get my program to run on bare metal?
Or at the very least tell Linux that my program is the most
important thing in the world and service it above all other things.
I am trying to create a timing signal with the Pi.  It is doing it
but the jitter is pretty bad.
I have researched trying to use an interrupt but there is a pretty
low limit on how many times per second you can fire a hardware
interrupt.
Too low for my application.



--

Re: [AFMUG] OT Raspberry PI

[chuck]

I am thinking of using some shift registers instead of using the PI output 
directly as the timing signal. 

Use the PI to load them.  

I love me some hardware design anyhow


From: Colin Stanners 
Sent: Thursday, February 22, 2018 3:59 PM
To: af@afmug.com 
Subject: Re: [AFMUG] OT Raspberry PI

Other than setting the process priority, you may need a custom kernel. See 
https://medium.com/@metebalci/latency-of-raspberry-pi-3-on-standard-and-real-time-linux-4-9-kernel-2d9c20704495
 


On Feb 22, 2018 4:48 PM, <ch...@wbmfg.com> wrote:

  Anyone know how to get my program to run on bare metal?

  Or at the very least tell Linux that my program is the most important thing 
in the world and service it above all other things.

  I am trying to create a timing signal with the Pi.  It is doing it but the 
jitter is pretty bad.  

  I have researched trying to use an interrupt but there is a pretty low limit 
on how many times per second you can fire a hardware interrupt.
  Too low for my application.  

Re: [AFMUG] OT Raspberry PI

[Colin Stanners]

Other than setting the process priority, you may need a custom kernel. See
https://medium.com/@metebalci/latency-of-raspberry-pi-3-on-standard-and-real-time-linux-4-9-kernel-2d9c20704495


On Feb 22, 2018 4:48 PM,  wrote:

> Anyone know how to get my program to run on bare metal?
>
> Or at the very least tell Linux that my program is the most important
> thing in the world and service it above all other things.
>
> I am trying to create a timing signal with the Pi.  It is doing it but the
> jitter is pretty bad.
>
> I have researched trying to use an interrupt but there is a pretty low
> limit on how many times per second you can fire a hardware interrupt.
> Too low for my application.
>

Re: [AFMUG] OT Raspberry PI

[Adam Moffett]

You can change the niceness of the process with the "nice" command.
There's preemption in the Linux kernel, but I don't know how to make it 
happen.



-- Original Message --
From: ch...@wbmfg.com
To: af@afmug.com
Sent: 2/22/2018 5:48:11 PM
Subject: [AFMUG] OT Raspberry PI


Anyone know how to get my program to run on bare metal?

Or at the very least tell Linux that my program is the most important 
thing in the world and service it above all other things.


I am trying to create a timing signal with the Pi.  It is doing it but 
the jitter is pretty bad.


I have researched trying to use an interrupt but there is a pretty low 
limit on how many times per second you can fire a hardware interrupt.

Too low for my application.