I haven't seen this mentioned here. It seems that it might be relevant:
https://www.raspberrypi.org/forums/viewtopic.php?t=206747
--
atp
"A motorcycle is a bicycle with a pandemonium attachment and is
designed for the especial use of mechanical geniuses, daredevils and
lunatics."
— George Fitch,
s priority inversions etc. and would therefore be broken that it
continues down the path of non-real time.
Simply mind boggling.
John
> -Original Message-
> From: andy pugh [mailto:bodge...@gmail.com]
> Sent: June-22-18 5:47 AM
> To: Enhanced Machine Controller (EMC)
> Subject:
On Fri, 22 Jun 2018, John Dammeyer wrote:
Date: Fri, 22 Jun 2018 08:39:55 -0700
From: John Dammeyer
Reply-To: "Enhanced Machine Controller (EMC)"
To: "'Enhanced Machine Controller (EMC)'"
Subject: Re: [Emc-users] Raspberry Pi PREEMPT-RT
I believe the Beagle
around for a usb2-sata adapter and I'll try it on a 60 GB
SSD. The usb spinning rust drive redefines slow, gotta be something
faster about.
> > -Original Message-
> > From: andy pugh [mailto:bodge...@gmail.com]
> > Sent: June-22-18 5:47 AM
> > To: Enhanced Machin
There are at least five different kinds of real time Linux.I about 20
years ago I write firmware for a CCD camera that run on real-time linux.
Real-Time Lins was not new then.
But there is a problem with all RT systems. You get low latency an
predictable timing but at the cost of efficiency.
On 22 June 2018 at 18:52, Chris Albertson wrote:
> With five different RT solutions Linux is good at RT.
>
> From a Linux CNC user's perspective it might seem that the choices are more
> limited.
Yes, LinuxCNC only works with three of the five.
--
atp
"A motorcycle is a bicycle with a pandemo
On 06/22/2018 11:10 AM, Peter C. Wallace wrote:
Linux has had real time kernels for more than 10 years
rt-linux was used by the original EMC (1) in about 1996 to
port the original EMC over from Sun hardware.
So, it has been about 22 years! Amazing! I got my first
EMC system running in 1997
xplain in simple elementary school level terms?
Thanks
John
> -Original Message-
> From: Jon Elson [mailto:el...@pico-systems.com]
> Sent: June-22-18 6:43 PM
> To: Enhanced Machine Controller (EMC)
> Subject: Re: [Emc-users] Raspberry Pi PREEMPT-RT
>
> On 06/22/2018 11:1
gt;
> So what does Linux do and what does PREMPT-RT do that's different. Maybe
> someone can explain in simple elementary school level terms?
>
> Thanks
> John
>
>
> > -Original Message-
> > From: Jon Elson [mailto:el...@pico-systems.com]
> > Sen
On Friday 22 June 2018 21:42:53 Jon Elson wrote:
> On 06/22/2018 11:10 AM, Peter C. Wallace wrote:
> > Linux has had real time kernels for more than 10 years
>
> rt-linux was used by the original EMC (1) in about 1996 to
> port the original EMC over from Sun hardware.
> So, it has been about 22 ye
On Friday 22 June 2018 08:47:05 andy pugh wrote:
> I haven't seen this mentioned here. It seems that it might be
> relevant:
>
> https://www.raspberrypi.org/forums/viewtopic.php?t=206747
I almost missed this, bookmarked now, thanks Andy.
This thread got into a serious list of questions about ho
I am baffled by this discussion.
LinuxCNC relies on a real-time kernel in one of three flavours. RTAI,
Xenomai or PREEMPT-RT.
LinuxCNC supplies either RTAI or PREMPT-RT as part of the Live-CD
images for x86 and amd-64 platforms but does not supply such kernels
for ARM.
So anyone wanting to run Li
On Saturday 23 June 2018 05:39:12 andy pugh wrote:
> I am baffled by this discussion.
>
> LinuxCNC relies on a real-time kernel in one of three flavours. RTAI,
> Xenomai or PREEMPT-RT.
>
> LinuxCNC supplies either RTAI or PREMPT-RT as part of the Live-CD
> images for x86 and amd-64 platforms but d
On 23.06.18 06:53, Gene Heskett wrote:
> On Saturday 23 June 2018 05:39:12 andy pugh wrote:
> Did I mention that usb-2, pi version, is slow yet? 749 megs to write, its
> making 367 bytes a second. I may as well send this and go back to bed.
> More news next month maybe? ;(
Yeah, July 17th at t
On Saturday 23 June 2018 07:27:49 Erik Christiansen wrote:
> On 23.06.18 06:53, Gene Heskett wrote:
> > On Saturday 23 June 2018 05:39:12 andy pugh wrote:
> > Did I mention that usb-2, pi version, is slow yet? 749 megs to
> > write, its making 367 bytes a second. I may as well send this and go
> >
The best and fastest storage I have on my RPi3 is via WiFi. I have files
NFS mounted. I seem to get about 90 Mbps speed.
One advantage of NFS mounted files is the same exact files are accessible
on my iMac or my Linux notebook. If I need to do something that takes a
lot of I/O I can do that on
On Saturday 23 June 2018 11:31:45 Chris Albertson wrote:
> The best and fastest storage I have on my RPi3 is via WiFi. I have
> files NFS mounted. I seem to get about 90 Mbps speed.
>
Thats about 4.5 x faster than wifi. Or are you on a 5GHz band?
I've had NFS in use in the past, but found its
On 06/23/2018 04:39 AM, andy pugh wrote:
I am baffled by this discussion.
LinuxCNC relies on a real-time kernel in one of three flavours. RTAI,
Xenomai or PREEMPT-RT.
LinuxCNC supplies either RTAI or PREMPT-RT as part of the Live-CD
images for x86 and amd-64 platforms but does not supply such k
That's Mbps, with a small b, bits per second. The speed is unimpressive.
Using only 2.5 GHz band the maximum rate is about 400 Mbps. The RPi3 is
only getting about 1/4 of what it should be able to do but still almost as
good as wired 100 BaseT.
On the same WiFi router my Mac gets just over 1,00
> > I am baffled by this discussion.
Not so much by the discussion but that it appears no one actually knows what
is going on other than that something is running on something.
> >
> > LinuxCNC relies on a real-time kernel in one of three flavours. RTAI,
> > Xenomai or PREEMPT-RT.
So what's the d
On 23 June 2018 at 18:03, John Dammeyer wrote:
>> > I am baffled by this discussion.
> So unless there is something significantly different between RTAI, Xenomai
> or PREEMPT-RT, that is the subject of PhD dissertations, why are there still
> 3 of them?
http://linuxgizmos.com/real-time-linux-ex
Excellent! Thanks Andy. All my google searches didn't turn up that link.
John
> On 23 June 2018 at 18:03, John Dammeyer
> wrote:
> >> > I am baffled by this discussion.
>
> > So unless there is something significantly different between RTAI,
> Xenomai
> > or PREEMPT-RT, that is the subject of
I tried to explain a little theory. There are different ways an RTOS can
implemented. Not only how it works under the hood but how RT tasks are
presented to the user.Are they special tasks using a separate API or
are they POSIX tasks? One version of this simply replaces the scheduler
and no
On 06/23/2018 12:03 PM, John Dammeyer wrote:
Clearly desktop Linux has some sort of RTOS (compared to
single user CP/M-80, CP/M-86, MSDOS, WIN-386) since it
allows multiple users to sign in.
That is not Real-Time, just a multi-user OS. No guarantees
of execution or latency.
Jon
1 PM
> To: Enhanced Machine Controller (EMC)
> Subject: Re: [Emc-users] Raspberry Pi PREEMPT-RT
>
> On 06/23/2018 12:03 PM, John Dammeyer wrote:
> > Clearly desktop Linux has some sort of RTOS (compared to
> > single user CP/M-80, CP/M-86, MSDOS, WIN-386) since it
> > a
On 24 June 2018 at 00:52, John Dammeyer wrote:
> So you are confirming that standard Linux like Ubuntu for a PC, the Raspian
> for the Pi or the Debian for the Beagle is just a multi-user OS and also not
> real time.
Yes. Which is why LinuxCNC requires one of RTAI, Xenomai or Preempt-RT to run.
On 06/23/2018 06:52 PM, John Dammeyer wrote:
Hi Jon,
So you are confirming that standard Linux like Ubuntu for a PC, the Raspian
for the Pi or the Debian for the Beagle is just a multi-user OS and also not
real time.
Yes, the standard OS is not real time. If the OS has a RT
option applied to
's usually only 1% or
so. Not good for stepper motors but fine for a lot of other automation
tasks.
John
> -Original Message-
> From: Jon Elson [mailto:el...@pico-systems.com]
> Sent: June-23-18 8:13 PM
> To: Enhanced Machine Controller (EMC)
> Subject: Re: [Emc-use
> John
>
>
>
>
> > -----Original Message-
> > From: Jon Elson [mailto:el...@pico-systems.com]
> > Sent: June-23-18 8:13 PM
> > To: Enhanced Machine Controller (EMC)
> > Subject: Re: [Emc-users] Raspberry Pi PREEMPT-RT
> >
> > On 06/23/2018 06:52 P
On 22 June 2018 at 13:47, andy pugh wrote:
> I haven't seen this mentioned here. It seems that it might be relevant:
>
> https://www.raspberrypi.org/forums/viewtopic.php?t=206747
I built this this weekend.
git clone https://github.com/raspberrypi/linux.git
git checkout rpi-4.14.y-rt
make menuco
On Sunday 05 August 2018 18:20:41 andy pugh wrote:
> On 22 June 2018 at 13:47, andy pugh wrote:
> > I haven't seen this mentioned here. It seems that it might be
> > relevant:
> >
> > https://www.raspberrypi.org/forums/viewtopic.php?t=206747
>
> I built this this weekend.
>
> git clone https://gi
On 6 August 2018 at 03:44, Gene Heskett wrote:
>> And I have a Pi running a realtime kernel.
>
> How did you install it to the sd card? Thats been a showstopper for me.
I compiled on the Pi.
> What type machine are you driving, lathe or mill?
Nothing, this was purely an exercise in seeing wha
On Sat, 23 Jun 2018 21:04:48 -0700
"John Dammeyer" wrote:
> But we are still talking about a Multi-Tasking, Round Robin Priority Driven
> OS right? Like 3 tasks with the same priority are time sliced with equal
> processing time? ...
Ordinary real time scheduling with EDF as first choice which
> From: Nicklas Karlsson [mailto:nicklas.karlsso...@gmail.com]
> On Sat, 23 Jun 2018 21:04:48 -0700
> "John Dammeyer" wrote:
>
> > But we are still talking about a Multi-Tasking, Round Robin Priority
Driven
> > OS right? Like 3 tasks with the same priority are time sliced with
equal
> > process
> > > Inter task communication done with pipes. A task can
> > > suspend on a pipe until it's written to by another one. ...
>
> I did a project like that last year with a Pi and a PIC32. The Pi just
> can't wake up fast enough so the PIC32 had to buffer thousands of CAN bus
> messages. Once th
Your buffer reading example is, I think a better example of soft real
time. Typically the way this is done is not to trigger on "buffer full"
but use a 70% threshold. My definition of "soft" means that it must be
fast enough to get the work done but there is some room for when each part
of the jo
On Sunday 24 June 2018 15:34:19 Chris Albertson wrote:
> Your buffer reading example is, I think a better example of soft real
> time. Typically the way this is done is not to trigger on "buffer
> full" but use a 70% threshold. My definition of "soft" means that it
> must be fast enough to get t
> What we have is the result of historic accident. EMC and machine control
> in general got its start when computers where EXPENSIVE. You design
> differently when you parts for five digit price tags than when you parts
> are nearly free. If computers cost $2 and two of them could fit on your
Maybe we've gone full circle. I just bought an $11 part on eBay. I it is
a CPLD. Like an FPGA but smaller and much less expensive and easier to
use. The programming software has a mode where yu can call up a library
of old 74LSxxx parts and drop them on a canvas and draw lies between pins.
The
On 06/24/2018 09:43 PM, Chris Albertson wrote:
Maybe we've gone full circle. I just bought an $11 part on eBay. I it is
a CPLD. Like an FPGA but smaller and much less expensive and easier to
use. The programming software has a mode where yu can call up a library
of old 74LSxxx parts and drop
On 6/24/2018 10:24 PM, Jon Elson wrote:
>
> I've stopped using the schematic entry stuff and learned VHDL. But,
> these things are amazingly powerful, fast, and not too-hard to program.
Ah...I miss the old days of manually programming fuse maps for CPLDs
with PALASM...
Yeah, not really...VHDL i
d after that it would run as a task.
And just like reading a novel, for absolutely no reason other than to do it.
End of aside:
John
> -Original Message-
> From: Chris Albertson [mailto:albertson.ch...@gmail.com]
> Sent: June-24-18 7:44 PM
> To: Enhanced Machine Controlle
re
"The programming software has a mode where yu can call up a library
of old 74LSxxx parts and drop them on a canvas and draw lies between pins
"
You talkin bout Cypress's PSoC Creator, Willis?
;-)
It doesnt sound like Xilinx or Altera's tools.
tomp
On Mon, Jun 25, 2018 at 9:43 AM, Chris Alberts
> Maybe we've gone full circle. I just bought an $11 part on eBay. I it is
> a CPLD. Like an FPGA but smaller and much less expensive and easier to
> use. The programming software has a mode where yu can call up a library
> of old 74LSxxx parts and drop them on a canvas and draw lies between p
On Sun, 24 Jun 2018 12:34:19 -0700
Chris Albertson wrote:
> Your buffer reading example is, I think a better example of soft real
> time. Typically the way this is done is not to trigger on "buffer full"
> but use a 70% threshold. My definition of "soft" means that it must be
> fast enough to g
On 06/24/2018 10:39 PM, Charles Steinkuehler wrote:
On 6/24/2018 10:24 PM, Jon Elson wrote:
I've stopped using the schematic entry stuff and learned VHDL. But,
these things are amazingly powerful, fast, and not too-hard to program.
Ah...I miss the old days of manually programming fuse maps for
On 06/25/2018 04:32 AM, TJoseph Powderly wrote:
re
"The programming software has a mode where yu can call up a library
of old 74LSxxx parts and drop them on a canvas and draw lies between pins
"
You talkin bout Cypress's PSoC Creator, Willis?
;-)
It doesnt sound like Xilinx or Altera's tools.
Xi
> From: Nicklas Karlsson [mailto:nicklas.karlsso...@gmail.com]
> On Sun, 24 Jun 2018 12:34:19 -0700
> Chris Albertson wrote:
>
> > Your buffer reading example is, I think a better example of soft real
> > time. Typically the way this is done is not to trigger on "buffer full"
> > but use a 70%
Many years ago now when the UHU DC Servo drive showed up as a collection of
TTL parts I started putting together the VHDL code to make it all out of one
FPGA. But ultimately for a lathe gear replacement all it did was track a
servo motor on the carriage Z axis to a spindle encoder through a series
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