Re: [Emc-users] FPGA arty

[Nicklas SB Karlsson]

A circuit with a reasonable fast CPU, Ethernet and the FPGA for an arbitrary 
number of communication ports, UART, SPI, CAN would probably be the ideal 
device for a linuxcnc server.

I read fast and can't figure out the CPU on this chip.

On Sat, 14 Oct 2017 18:05:52 +0700
TJoseph Powderly  wrote:

> Has anyone looked at 'arty' for linuxcnc/hal?
> http://rdepablos.merlitec.com/arty-and-linux-1-fpga . its nice to get the
> whole toolset with it inside 100$US.
> 
> Regards Tomp tjtr33
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Re: [Emc-users] FPGA arty

[TJoseph Powderly]

It has no CPU unless you build one from cells. There are soft cores
available. This is an add on card like mesa without any pci or ethernet
_yet_.

On Oct 14, 2017 7:22 PM, "Nicklas SB Karlsson" 
wrote:

> A circuit with a reasonable fast CPU, Ethernet and the FPGA for an
> arbitrary number of communication ports, UART, SPI, CAN would probably be
> the ideal device for a linuxcnc server.
>
> I read fast and can't figure out the CPU on this chip.
>
> On Sat, 14 Oct 2017 18:05:52 +0700
> TJoseph Powderly  wrote:
>
> > Has anyone looked at 'arty' for linuxcnc/hal?
> > http://rdepablos.merlitec.com/arty-and-linux-1-fpga . its nice to get
> the
> > whole toolset with it inside 100$US.
> >
> > Regards Tomp tjtr33
> > 
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> 
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Re: [Emc-users] FPGA arty

[Sebastian Kuzminsky]

Or check out Project Ice Storm, an open source Verilog tool chain for Lattice 
FPGAs: www.clifford.at/icestorm/

Works well with cheap dev boards like this: 
http://www.latticesemi.com/en/Products/DevelopmentBoardsAndKits/iCE40HX8KBreakoutBoard.aspx




 Original Message 
From: TJoseph Powderly 
Sent: October 14, 2017 5:05:52 AM MDT
To: "Enhanced Machine Controller (EMC)" 
Subject: [Emc-users] FPGA arty

Has anyone looked at 'arty' for linuxcnc/hal?
http://rdepablos.merlitec.com/arty-and-linux-1-fpga . its nice to get the
whole toolset with it inside 100$US.

Regards Tomp tjtr33
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Re: [Emc-users] FPGA arty --> communication hub, server

[Nicklas SB Karlsson]

I have been thinking about FPGA for a communication switch, it would be 
possible to get perfect timings. Then ordinary micro controllers could be used 
for implementing the hardware, the approach is similar to the new devices with 
so called Cortex-M-* PRUs but by using SPI, UART or maybe CAN it is possible to 
build more modular and add an insulation barrier.

The new devices with PRU may be a cheaaper solution for machines built in very 
large series. A modular architecture there different special hardware drivers 
could be combined is a better solution then building a lot of different 
mashines.


On Sat, 14 Oct 2017 08:58:27 -0600
Sebastian Kuzminsky  wrote:

> Or check out Project Ice Storm, an open source Verilog tool chain for Lattice 
> FPGAs: www.clifford.at/icestorm/
> 
> Works well with cheap dev boards like this: 
> http://www.latticesemi.com/en/Products/DevelopmentBoardsAndKits/iCE40HX8KBreakoutBoard.aspx
> 
> 
> 
> 
>  Original Message 
> From: TJoseph Powderly 
> Sent: October 14, 2017 5:05:52 AM MDT
> To: "Enhanced Machine Controller (EMC)" 
> Subject: [Emc-users] FPGA arty
> 
> Has anyone looked at 'arty' for linuxcnc/hal?
> http://rdepablos.merlitec.com/arty-and-linux-1-fpga . its nice to get the
> whole toolset with it inside 100$US.
> 
> Regards Tomp tjtr33
> --
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> engaging tech sites, Slashdot.org! http://sdm.link/slashdot
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> -- 
> Sebastian Kuzminsky
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Re: [Emc-users] FPGA arty --> communication hub, server

[Chris Albertson]

On Sat, Oct 14, 2017 at 8:47 AM, Nicklas SB Karlsson <
nicklas.karlsso...@gmail.com> wrote:

> I have been thinking about FPGA for a communication switch, it would be
> possible to get perfect timings. Then ordinary micro controllers could be
> used for implementing the hardware, the approach is similar to the new
> devices with so called Cortex-M-* PRUs but by using SPI, UART or maybe CAN
> it is possible to build more modular and add an insulation barrier.
>
> The new devices with PRU may be a cheaaper solution for machines built in
> very large series. A modular architecture there different special hardware
> drivers could be combined is a better solution then building a lot of
> different mashines.
>

The Cortex M Costs about $1 or some of them even less.  You can buy a
complete system on a PCB with connectors.  For under $3 shipping included.
  If you need to make something like a switch or control a few motors these
work well.  I have several of them.  I am using them for motion controller.

In terms of "compute power"  They are an order of magnitude above an
Arduino.  But not even close to a Pi 3 or BBB.

Lots of ways to program them
1) You can install an Arduino boot loader then use the Arduino IDE
2) Same as #1 but use "mbed"  This is a big step up on features and only
 little harder to use tham Arduino
3) Just pain gcc and makefile with or without Eclipse

Don't call this a "PRU" they are not related and are much more powerful.
But you use them about the same way.  Linux and linux apps run on a Cortex
A processor like the Pi3 and the heard real time stuff goes on the Cortex M
and yours some kind of serial link to connect them

I'm using one of the boards liked to below to control two motors using
PID.  I have two PIP loops running and the optical encoder is sending about
11,000 interrupts per second for each motor.   I run the PIP loops and get
commands over a serial link and also monitor the motorcars and motor
h-bridge for over temperature and over current and look for motor stalls.
For this I use about 1/2 the computer's capacity.  All written in C++

Here is one place to buy them:
ebay.com/itm/STM32F103C8T6-ARM-STM32...


I would not go with an FPGA unless you need very high speed where signals
are in the teen's of megahertz at least, up to GHz.   The FPGA is much
harder to program them an ARM Cortex-M.

If I were building a machine tool controller from scratch I'd run much of
it on a small computer under Linux then I'd get as many of these Cortex-M
chips as required.  Each could handle between 2 and 6 axis.



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Re: [Emc-users] FPGA arty --> FPPGA communication hub, server

[Nicklas Karlsson]

> > I have been thinking about FPGA for a communication switch, it would be
> > possible to get perfect timings. Then ordinary micro controllers could be
> > used for implementing the hardware, the approach is similar to the new
> > devices with so called Cortex-M-* PRUs but by using SPI, UART or maybe CAN
> > it is possible to build more modular and add an insulation barrier.
> >
> > The new devices with PRU may be a cheaaper solution for machines built in
> > very large series. A modular architecture there different special hardware
> > drivers could be combined is a better solution then building a lot of
> > different mashines.
> >
> 
> The Cortex M Costs about $1 or some of them even less.  You can buy a
> complete system on a PCB with connectors.  For under $3 shipping included.
>   If you need to make something like a switch or control a few motors these
> work well.  I have several of them.  I am using them for motion controller.

Yes I know it very well and also have a few of them.

> In terms of "compute power"  They are an order of magnitude above an
> Arduino.  But not even close to a Pi 3 or BBB.

This is good enough for one motor probably with plenty margin.

> ...
> I'm using one of the boards liked to below to control two motors using
> PID.  I have two PIP loops running and the optical encoder is sending about
> 11,000 interrupts per second for each motor.   I run the PIP loops and get
> commands over a serial ...

Similar as I do.


> I would not go with an FPGA unless you need very high speed where signals
> are in the teen's of megahertz at least, up to GHz.   The FPGA is much
> harder to program them an ARM Cortex-M.
> 
> If I were building a machine tool controller from scratch I'd run much of
> it on a small computer under Linux then I'd get as many of these Cortex-M
> chips as required.  Each could handle between 2 and 6 axis.

There I am heading. The FPGA could give me as many serial communication ports 
as needed with perfect communication period. Second option is to add a Ethercat 
slave device on each device.


Regards Nicklas Karlsson

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Re: [Emc-users] FPGA arty --> FPPGA communication hub, server

[Gene Heskett]

On Monday 16 October 2017 11:28:40 Nicklas Karlsson wrote:

> > > I have been thinking about FPGA for a communication switch, it
> > > would be possible to get perfect timings. Then ordinary micro
> > > controllers could be used for implementing the hardware, the
> > > approach is similar to the new devices with so called Cortex-M-*
> > > PRUs but by using SPI, UART or maybe CAN it is possible to build
> > > more modular and add an insulation barrier.
> > >
> > > The new devices with PRU may be a cheaaper solution for machines
> > > built in very large series. A modular architecture there different
> > > special hardware drivers could be combined is a better solution
> > > then building a lot of different mashines.
> >
> > The Cortex M Costs about $1 or some of them even less.  You can buy
> > a complete system on a PCB with connectors.  For under $3 shipping
> > included. If you need to make something like a switch or control a
> > few motors these work well.  I have several of them.  I am using
> > them for motion controller.
>
> Yes I know it very well and also have a few of them.
>
> > In terms of "compute power"  They are an order of magnitude above an
> > Arduino.  But not even close to a Pi 3 or BBB.
>
> This is good enough for one motor probably with plenty margin.
>
> > ...
> > I'm using one of the boards liked to below to control two motors
> > using PID.  I have two PIP loops running and the optical encoder is
> > sending about 11,000 interrupts per second for each motor.   I run
> > the PIP loops and get commands over a serial ...
>
> Similar as I do.
>
> > I would not go with an FPGA unless you need very high speed where
> > signals are in the teen's of megahertz at least, up to GHz.   The
> > FPGA is much harder to program them an ARM Cortex-M.
> >
> > If I were building a machine tool controller from scratch I'd run
> > much of it on a small computer under Linux then I'd get as many of
> > these Cortex-M chips as required.  Each could handle between 2 and 6
> > axis.
>
> There I am heading. The FPGA could give me as many serial
> communication ports as needed with perfect communication period.
> Second option is to add a Ethercat slave device on each device.
>
>
This sounds appetizing.  Lets say you've installed LCNC on a rock64. Now 
the rock64 has a 5 Gigabaud usb3 port, and hubs for usb3 stuff are 
showing up, which would allow to have something besides the currently 
mounted 1Tb seagate usb3 backup disk. With a hub, and I found them as 
wide as 13 ports just last week, how hard would it be to make one of 
these things with a usb3 interface, just plugging in enough for the 
number of axises the machine has? 

I just bought another of the dells I am using on the bigger mill, might 
be here by the end of the week, but I've also got two rock64's, which 
have more than enough housepower to run this stuff. With the usb2 
bottleneck in the i/o gone, the rock64 is many times faster than a pi3b 
and its running my big lathe very well once a reboot, sometimes several, 
has managed to find the local keyboard and mouse 100% of the time.

But interfacing to the real world of a 7i90 I've not been able to do 
because the hm2_rpspi.ko driver is loaded with code to make sure its 
running on a pi. I am attempting to excise those checks, because rock64 
claims to be pi compatible in its gpio, but have not been successful 
enough to even crash the rock64.
  
So there is your "what if" for the week. :)
 
> Regards Nicklas Karlsson
>
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Cheers, Gene Heskett
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 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
Genes Web page 

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Re: [Emc-users] FPGA arty --> FPPGA communication hub, server

[Nicklas Karlsson]

> > > ...
> > > I'm using one of the boards liked to below to control two motors
> > > using PID.  I have two PIP loops running and the optical encoder is
> > > sending about 11,000 interrupts per second for each motor.   I run
> > > the PIP loops and get commands over a serial ...
> >
> > Similar as I do.
> >
> > > I would not go with an FPGA unless you need very high speed where
> > > signals are in the teen's of megahertz at least, up to GHz.   The
> > > FPGA is much harder to program them an ARM Cortex-M.
> > >
> > > If I were building a machine tool controller from scratch I'd run
> > > much of it on a small computer under Linux then I'd get as many of
> > > these Cortex-M chips as required.  Each could handle between 2 and 6
> > > axis.
> >
> > There I am heading. The FPGA could give me as many serial
> > communication ports as needed with perfect communication period.
> > Second option is to add a Ethercat slave device on each device.
> >
> >
> This sounds appetizing.  Lets say you've installed LCNC on a rock64. ...

It's a media board, it could play good music and show pictures of beatiful 
woman but I need serial ports. I have already looked at another device, it 
should be good enough then running without user interface.


Nicklas Karlsson

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Re: [Emc-users] FPGA arty --> FPPGA communication hub, server

[Nicklas Karlsson]

> On Monday 16 October 2017 11:28:40 Nicklas Karlsson wrote:
> 
> > > > I have been thinking about FPGA for a communication switch, it
> > > > would be possible to get perfect timings. Then ordinary micro
> > > > controllers could be used for implementing the hardware, the
> > > > approach is similar to the new devices with so called Cortex-M-*
> > > > PRUs but by using SPI, UART or maybe CAN it is possible to build
> > > > more modular and add an insulation barrier.
> > > >
> > > > The new devices with PRU may be a cheaaper solution for machines
> > > > built in very large series. A modular architecture there different
> > > > special hardware drivers could be combined is a better solution
> > > > then building a lot of different mashines.
> > >
> > > The Cortex M Costs about $1 or some of them even less.  You can buy
> > > a complete system on a PCB with connectors.  For under $3 shipping
> > > included. If you need to make something like a switch or control a
> > > few motors these work well.  I have several of them.  I am using
> > > them for motion controller.
> >
> > Yes I know it very well and also have a few of them.
> >
> > > In terms of "compute power"  They are an order of magnitude above an
> > > Arduino.  But not even close to a Pi 3 or BBB.
> >
> > This is good enough for one motor probably with plenty margin.
> >
> > > ...
> > > I'm using one of the boards liked to below to control two motors
> > > using PID.  I have two PIP loops running and the optical encoder is
> > > sending about 11,000 interrupts per second for each motor.   I run
> > > the PIP loops and get commands over a serial ...
> >
> > Similar as I do.
> >
> > > I would not go with an FPGA unless you need very high speed where
> > > signals are in the teen's of megahertz at least, up to GHz.   The
> > > FPGA is much harder to program them an ARM Cortex-M.
> > >
> > > If I were building a machine tool controller from scratch I'd run
> > > much of it on a small computer under Linux then I'd get as many of
> > > these Cortex-M chips as required.  Each could handle between 2 and 6
> > > axis.
> >
> > There I am heading. The FPGA could give me as many serial
> > communication ports as needed with perfect communication period.
> > Second option is to add a Ethercat slave device on each device.
> >
> >
> This sounds appetizing.  Lets say you've installed LCNC on a rock64. Now 
> the rock64 has a 5 Gigabaud usb3 port, and hubs for usb3 stuff are 
> showing up, which would allow to have something besides the currently 
> mounted 1Tb seagate usb3 backup disk. With a hub, and I found them as 
> wide as 13 ports just last week, how hard would it be to make one of 
> these things with a usb3 interface, just plugging in enough for the 
> number of axises the machine has?

I am planning something similar, FPGA was my first thought.

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Re: [Emc-users] FPGA arty --> FPPGA communication hub, server

[Chris Albertson]

What you are asking is if a USB bus would make a good network for real-time
data.   The problem is latency.  the bandwidth is OK but USB is
packetized.  Ethernet has this same problem very good bandwidth but for
latency.

Eithercat tries to address latency placing multiple payloads in ovary
packets.  This reduces latency to whatever rate you can send packets.
Notice to d this they completely ignore the Ethernet protocol and are
repurposing the hardware.   This is a good idea because Ethercat can
leverage exiting hardware and cables.

I see no reason why you could not do the same thing with USB3.  That is to
repurpose existing hardware and "simply" re-write new drivers.

But WHY?  Why bother to repurpose USB and write all that software when
Ethercat is available for free.  Free and Open source Ethercat masters
already run on Linux.

OK you might argue that USB3 can be faster then Ethernet.   Faster bit
rates but who cares, for this use case latency matters more then any other
spec. and Ethercat runs at  1 gigabit now and it you have more money at 10
gigabits.

One HUGE argument against inventing a "USB3cat" is cable length.  USB is
just not going to work in a large shop let alone a factory.  Ethernet on
the other hand can go at least 100 meters using cheap coper wire and a few
kilometers over fiber.

I think the FPGA message switch only solves one problem. That is you want
to use a non-bus point to point transport protocol for communication
between many end points.  These can work but not so well for real time.
Every possible design has serious performance issues either nondetermistic
latency or it's just slow.   These are used but that is the trade off.
These switches either act like a N-way mux or a store and forward switch

My opinion:  You are more productive if you spend your limited time
creating stuff that you can't get for free.  For example I'd never write C
compiler.

On Thu, Oct 19, 2017 at 2:28 PM, Nicklas Karlsson <
nicklas.karlsso...@gmail.com> wrote:

> > On Monday 16 October 2017 11:28:40 Nicklas Karlsson wrote:
> >
> > > > > I have been thinking about FPGA for a communication switch, it
> > > > > would be possible to get perfect timings. Then ordinary micro
> > > > > controllers could be used for implementing the hardware, the
> > > > > approach is similar to the new devices with so called Cortex-M-*
> > > > > PRUs but by using SPI, UART or maybe CAN it is possible to build
> > > > > more modular and add an insulation barrier.
> > > > >
> > > > > The new devices with PRU may be a cheaaper solution for machines
> > > > > built in very large series. A modular architecture there different
> > > > > special hardware drivers could be combined is a better solution
> > > > > then building a lot of different mashines.
> > > >
> > > > The Cortex M Costs about $1 or some of them even less.  You can buy
> > > > a complete system on a PCB with connectors.  For under $3 shipping
> > > > included. If you need to make something like a switch or control a
> > > > few motors these work well.  I have several of them.  I am using
> > > > them for motion controller.
> > >
> > > Yes I know it very well and also have a few of them.
> > >
> > > > In terms of "compute power"  They are an order of magnitude above an
> > > > Arduino.  But not even close to a Pi 3 or BBB.
> > >
> > > This is good enough for one motor probably with plenty margin.
> > >
> > > > ...
> > > > I'm using one of the boards liked to below to control two motors
> > > > using PID.  I have two PIP loops running and the optical encoder is
> > > > sending about 11,000 interrupts per second for each motor.   I run
> > > > the PIP loops and get commands over a serial ...
> > >
> > > Similar as I do.
> > >
> > > > I would not go with an FPGA unless you need very high speed where
> > > > signals are in the teen's of megahertz at least, up to GHz.   The
> > > > FPGA is much harder to program them an ARM Cortex-M.
> > > >
> > > > If I were building a machine tool controller from scratch I'd run
> > > > much of it on a small computer under Linux then I'd get as many of
> > > > these Cortex-M chips as required.  Each could handle between 2 and 6
> > > > axis.
> > >
> > > There I am heading. The FPGA could give me as many serial
> > > communication ports as needed with perfect communication period.
> > > Second option is to add a Ethercat slave device on each device.
> > >
> > >
> > This sounds appetizing.  Lets say you've installed LCNC on a rock64. Now
> > the rock64 has a 5 Gigabaud usb3 port, and hubs for usb3 stuff are
> > showing up, which would allow to have something besides the currently
> > mounted 1Tb seagate usb3 backup disk. With a hub, and I found them as
> > wide as 13 ports just last week, how hard would it be to make one of
> > these things with a usb3 interface, just plugging in enough for the
> > number of axises the machine has?
>
> I am planning something similar, FPGA was my first thought.
>
> -

Re: [Emc-users] FPGA arty --> FPPGA communication hub, server

[andy pugh]

On 19 October 2017 at 23:58, Chris Albertson  wrote:

> OK you might argue that USB3 can be faster then Ethernet.   Faster bit
> rates but who cares, for this use case latency matters more then any other
> spec.

Indeed, the EPP parallel port works splendidly for the Pico and (some)
Mesa cards.
The total payload every mS is a few dozen bytes.

Though: There is some evidence that there was a realtime USB effort, I
found the source code on the RTAI repository (but can't immediately
find it now).


-- 
atp
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designed for the especial use of mechanical geniuses, daredevils and
lunatics."
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Re: [Emc-users] FPGA arty --> FPPGA communication hub, server

[Chris Albertson]

You might be thinking of USB isochronous transfer mode.
This is how we send audio and video.   It allows the sending of
periodic packets at a constant rate.

I don't know how well it would work for machine control.   It was designed
for constant rate not low latency but it might have good latency too.

> Though: There is some evidence that there was a realtime USB effort, I
> found the source code on the RTAI repository (but can't immediately
> find it now).

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Re: [Emc-users] FPGA arty --> FPPGA communication hub, server

[Jon Elson]

On 10/19/2017 07:08 PM, andy pugh wrote:

On 19 October 2017 at 23:58, Chris Albertson  wrote:


OK you might argue that USB3 can be faster then Ethernet.   Faster bit
rates but who cares, for this use case latency matters more then any other
spec.

Indeed, the EPP parallel port works splendidly for the Pico and (some)
Mesa cards.
The total payload every mS is a few dozen bytes.

Yes, on a 1 GHz Pentium 4 class CPU, with a generic parallel 
port, the ENTIRE servo thread for 4 axes takes about 150 us!
This requires a handshake (in hardware) for every byte 
transferred. So, it is about 50 us for the read of encoder 
counts, 50 us for the PID calculation and then 50 us to send 
the new velocities to whatever (servo or stepper) is in use.


Jon

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Re: [Emc-users] FPGA arty --> FPPGA communication hub, server

[andy pugh]

On 20 October 2017 at 02:45, Chris Albertson  wrote:
> You might be thinking of USB isochronous transfer mode.

No, I am thinking of a folder called "USB-RT" or similar that was a
sub-project of RTAI. But it looked abandoned 5 years ago and I can't
find it now.

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Re: [Emc-users] FPGA arty --> FPPGA communication hub, server

[andy pugh]

On 20 October 2017 at 10:54, andy pugh  wrote:
> I can't
> find it now.

I found it
https://www.rtai.org/userfiles/downloads/RTAICONTRIB/

But:
http://mail.rtai.org/pipermail/rtai/2014-November/026568.html


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Re: [Emc-users] FPGA arty --> FPPGA communication hub, server

[Nicklas Karlsson]

On Thu, 19 Oct 2017 15:58:59 -0700
Chris Albertson  wrote:

> What you are asking is if a USB bus would make a good network for real-time
> data.   The problem is latency.  the bandwidth is OK but USB is
> packetized.  Ethernet has this same problem very good bandwidth but for
> latency.

It's not just latency, there is a need for many small packets. Ethercat solves 
the many small packets problem by method all nodes could send in same packet.

> Eithercat tries to address latency placing multiple payloads in ovary
> packets.  This reduces latency to whatever rate you can send packets.
> Notice to d this they completely ignore the Ethernet protocol and are
> repurposing the hardware.   This is a good idea because Ethercat can
> leverage exiting hardware and cables.

Indeed it is, as I understand principle is same as cascade coupled shift 
registers but with possibility to recalculate CRC checksum then packet is 
passed thru.

> But WHY?  Why bother to repurpose USB and write all that software when
> Ethercat is available for free.  Free and Open source Ethercat masters
> already run on Linux.

How about the hardware, is this principle patented?

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Re: [Emc-users] FPGA arty --> FPPGA communication hub, server

[Chris Albertson]

>> But WHY?  Why bother to repurpose USB and write all that software when
>> Ethercat is available for free.  Free and Open source Ethercat masters
>> already run on Linux.
>
> How about the hardware, is this principle patented?

Don't know abut patients but it seems to be available and Open Source and
works with LinuxCNC

some instructions here: http://wiki.linuxcnc.org/cgi-bin/wiki.pl?
EtherCatDriver


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Re: [Emc-users] FPGA arty --> FPPGA communication hub, server

[Nicklas Karlsson]

> >> But WHY?  Why bother to repurpose USB and write all that software when
> >> Ethercat is available for free.  Free and Open source Ethercat masters
> >> already run on Linux.
> >
> > How about the hardware, is this principle patented?
> 
> Don't know abut patients but it seems to be available and Open Source and
> works with LinuxCNC
> 
> some instructions here: http://wiki.linuxcnc.org/cgi-bin/wiki.pl?
> EtherCatDriver

Yes and there are hardware available 
http://www.microchip.com/wwwproducts/en/LAN9252 or Beckhoff and SPI may be used 
to communicate with slave controller.

I do not have time right now but will probably add later on. During the mean 
time I could use SPI. First I have to learn more about Ethercat then I have 
todo hardware and then software, it will take quite a lot of time. SPI I 
already tried maybe a month or two ago but had to add a fourth signal to the 
insulation barrier, it will give me at least 5-10 times more bandwidth than 
needed so I could chose to stay.


Nicklas Karlsson

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Re: [Emc-users] FPGA arty --> FPPGA communication hub, server

[Nicklas Karlsson]

> >> But WHY?  Why bother to repurpose USB and write all that software when
> >> Ethercat is available for free.  Free and Open source Ethercat masters
> >> already run on Linux.
> >
> > How about the hardware, is this principle patented?
> 
> Don't know abut patients but it seems to be available and Open Source and
> works with LinuxCNC
> 
> some instructions here: http://wiki.linuxcnc.org/cgi-bin/wiki.pl?
> EtherCatDriver

You know why I am obsessed with the SPI port?

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Re: [Emc-users] FPGA arty --> FPPGA communication hub, server (real time communication)

[Nicklas Karlsson]

> >> But WHY?  Why bother to repurpose USB and write all that software when
> >> Ethercat is available for free.  Free and Open source Ethercat masters
> >> already run on Linux.
> >
> > How about the hardware, is this principle patented?
> 
> Don't know abut patients but it seems to be available and Open Source and
> works with LinuxCNC
> 
> some instructions here: http://wiki.linuxcnc.org/cgi-bin/wiki.pl?
> EtherCatDriver

I might have to give up SPI. It work excellent, I send packets at a rate of 
16kHz although there should be enough time for packets of a rate of 32Khz at 
current speed and higher speed is possible. I send to four axis and this is 
handled perfect at a packet rate of 4kHz although a packet rate of 8kHz should 
be possible and this is 4-8 times more than needed.

Unfortunately the isolation barrier circuit have an enable propagation delay of 
8.5µs maximum either to low or high while a 11 byte packet take 17.6µs so this 
delay will use about a third of the bandwidth at 10Mbit/s and it will become 
worse if packets are smaller or speed increased.

Even though SPI is easy to use and perform excellent it might be better to give 
up because of this enable delay and spend the time on Ethercat. Or maybe the 
analog REM switch. Or does anybody have a suggestion of cheap SPI switch?


Nicklas Karlsson

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Re: [Emc-users] FPGA arty --> FPPGA communication hub, server (real time communication)

[Chris Albertson]

> Unfortunately the isolation barrier circuit have an enable propagation
> delay of 8.5µs maximum either to low or high while a 11 byte packet take
> 17.6µs so this delay will use about a third of the bandwidth at 10Mbit/s
> and it will become worse if packets are smaller or speed increased.
>
>
 Do you really need isolation across an SPI link?   Why not just use a
common ground.

You do want isolation between the high voltage motor and the digital
controller.  But if you already have this you don't need another layer.

Ethernet is galvanically isolated and runs at 1GHz.  Proof that you could
isolate your 10MHz SPI link but do you need to?

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Re: [Emc-users] FPGA arty --> FPPGA communication hub, server (real time communication)

[John Dammeyer]

> -Original Message-
> From: Nicklas Karlsson [mailto:nicklas.karlsso...@gmail.com]
> Sent: October-21-17 9:58 AM
> To: Enhanced Machine Controller (EMC)
> Subject: Re: [Emc-users] FPGA arty --> FPPGA communication hub, server
(real
> time communication)
> 
> > >> But WHY?  Why bother to repurpose USB and write all that software
when
> > >> Ethercat is available for free.  Free and Open source Ethercat
masters
> > >> already run on Linux.
> > >
> > > How about the hardware, is this principle patented?
> >
> > Don't know abut patients but it seems to be available and Open Source
and
> > works with LinuxCNC
> >
> > some instructions here: http://wiki.linuxcnc.org/cgi-bin/wiki.pl?
> > EtherCatDriver
> 
> I might have to give up SPI. It work excellent, I send packets at a rate
of 16kHz
> although there should be enough time for packets of a rate of 32Khz at
current
> speed and higher speed is possible. I send to four axis and this is
handled
> perfect at a packet rate of 4kHz although a packet rate of 8kHz should be
> possible and this is 4-8 times more than needed.
> 
> Unfortunately the isolation barrier circuit have an enable propagation
delay of
> 8.5µs maximum either to low or high while a 11 byte packet take 17.6µs so
this
> delay will use about a third of the bandwidth at 10Mbit/s and it will
become
> worse if packets are smaller or speed increased.
> 
> Even though SPI is easy to use and perform excellent it might be better to
give
> up because of this enable delay and spend the time on Ethercat. Or maybe
the
> analog REM switch. Or does anybody have a suggestion of cheap SPI switch?
> 
> 
> Nicklas Karlsson
> 
I just did a project transferring CAN messages that were received and
buffered with a PIC32.  The PIC32 acted as a slave SPI device to a PiZeroW
which used the WiringPi library to transfer 16 byte packets as master to the
PIC32.  The clock rate was 5MHz.  Each 16 Byte message represented a CAN
message on the bus at 250kbps.The system was able to handle a saturated
CAN bus where the packet length is about 120bits or 480uS.  That works out
to just over 2083 messages per second.  Since each message is 16 bytes or
128 bits that's an average of 266Kbps.  Easily handled by 5 Mbps SPI.  

I have no idea what is available for PC level hardware to do SPI
communications though nor if that rate is fast enough for what you want to
do.

John 


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Re: [Emc-users] FPGA arty --> FPPGA communication hub, server (real time communication)

[Nicklas Karlsson]

> to just over 2083 messages per second.  Since each message is 16 bytes or
> 128 bits that's an average of 266Kbps.  Easily handled by 5 Mbps SPI.  
> 
> I have no idea what is available for PC level hardware to do SPI
> communications though nor if that rate is fast enough for what you want to
> do.

SPI is available in almost all new micro controllers and it's fast so this is 
the reason I stubbornly tried to use it but finally almost have give up.

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Re: [Emc-users] FPGA arty --> FPPGA communication hub, server (real time communication)

[Nicklas Karlsson]

> > Unfortunately the isolation barrier circuit have an enable propagation
> > delay of 8.5µs maximum either to low or high while a 11 byte packet take
> > 17.6µs so this delay will use about a third of the bandwidth at 10Mbit/s
> > and it will become worse if packets are smaller or speed increased.
> >
> >
>  Do you really need isolation across an SPI link?   Why not just use a
> common ground.

Well as is now but I could change to a driver which actually is cheaper and 
then I do not have to pay money for isolation. An added bonus is isolation 
barrier latency will dissappear. I forgot about this, it's really great you 
remind me !!

> You do want isolation between the high voltage motor and the digital
> controller.  But if you already have this you don't need another layer.

Yes, I forgot for some reason I got depressed and didn't thinkg about adding 
this isolation barrier.

> Ethernet is galvanically isolated and runs at 1GHz.  Proof that you could
> isolate your 10MHz SPI link but do you need to?

Sometimes but mostly not.


Regards Nicklas Karlsson

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Re: [Emc-users] FPGA arty --> FPPGA communication hub, server (real time communication)

[John Dammeyer]

> -Original Message-
> From: Nicklas Karlsson [mailto:nicklas.karlsso...@gmail.com]
> Sent: October-21-17 11:40 AM
> To: Enhanced Machine Controller (EMC)
> Subject: Re: [Emc-users] FPGA arty --> FPPGA communication hub, server
(real
> time communication)
> 
> > to just over 2083 messages per second.  Since each message is 16 bytes
or
> > 128 bits that's an average of 266Kbps.  Easily handled by 5 Mbps SPI.
> >
> > I have no idea what is available for PC level hardware to do SPI
> > communications though nor if that rate is fast enough for what you want
to
> > do.
> 
> SPI is available in almost all new micro controllers and it's fast so this
is the
> reason I stubbornly tried to use it but finally almost have give up.
> 
It's available on pretty well any processor so it's more a matter of
choosing your weapon.  But still, you have to get the information from the
PC to the controller.  If you use USB then you don't need SPI.  If you use
Ethernet then you don't need SPI.  CAN bus isn't really fast enough for full
motion control unless you are just shipping messages to do the motion.

So you're back to needing to use the real time kernel or something that
isn't hung up by 'stuff' to get motion information out there.  Which is why
I don't quite understand what you are trying to accomplish.

John



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Re: [Emc-users] FPGA arty --> FPPGA communication hub, server (real time communication)

[Gene Heskett]

On Saturday 21 October 2017 14:39:33 Nicklas Karlsson wrote:

> > to just over 2083 messages per second.  Since each message is 16
> > bytes or 128 bits that's an average of 266Kbps.  Easily handled by 5
> > Mbps SPI.
> >
> > I have no idea what is available for PC level hardware to do SPI
> > communications though nor if that rate is fast enough for what you
> > want to do.
>
> SPI is available in almost all new micro controllers and it's fast so
> this is the reason I stubbornly tried to use it but finally almost
> have give up.
>
We have an spi driver for the pi's, but someone is going to need to fix 
it so it can run on most of the armv7/8's, or better yet, the arm64 
which is what the rock64 is built out of. I don't know about the SPI bus 
on the rock64, but the rest of the rock64 plumb blows the doors off a 
pi-3b. The rock64 doesn't have the usb-2 pinhole all the data i/o except 
gpio, has to negotiate a turn to get in or out. It is in the apt pulls 
however, and works well, but only on the pi's.

Cheers, Gene Heskett
-- 
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 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
Genes Web page 

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Re: [Emc-users] FPGA arty --> FPPGA communication hub, server (real time communication)

[Gene Heskett]

On Saturday 21 October 2017 15:40:38 John Dammeyer wrote:

> > -Original Message-
> > From: Nicklas Karlsson [mailto:nicklas.karlsso...@gmail.com]
> > Sent: October-21-17 11:40 AM
> > To: Enhanced Machine Controller (EMC)
> > Subject: Re: [Emc-users] FPGA arty --> FPPGA communication hub,
> > server
>
> (real
>
> > time communication)
> >
> > > to just over 2083 messages per second.  Since each message is 16
> > > bytes
>
> or
>
> > > 128 bits that's an average of 266Kbps.  Easily handled by 5 Mbps
> > > SPI.

SPI, as its working on a pi-3b, writes to a 7i90 at 41 Mbps, and reads 
back at 25 Mbps.

> > > I have no idea what is available for PC level hardware to do SPI
> > > communications though nor if that rate is fast enough for what you
> > > want

I've not been able to find anything in the way of pci or pci-e cards for 
a pc. And even then, the length of cable will kill quite a bit of speed.

The cable from the pi to the 7i90's 26 pin header is about an inch long.

> to
>
> > > do.
> >
> > SPI is available in almost all new micro controllers and it's fast
> > so this
>
> is the
>
> > reason I stubbornly tried to use it but finally almost have give up.
>
> It's available on pretty well any processor so it's more a matter of
> choosing your weapon.  But still, you have to get the information from
> the PC to the controller.  If you use USB then you don't need SPI.  If
> you use Ethernet then you don't need SPI.  CAN bus isn't really fast
> enough for full motion control unless you are just shipping messages
> to do the motion.
>
> So you're back to needing to use the real time kernel or something
> that isn't hung up by 'stuff' to get motion information out there. 
> Which is why I don't quite understand what you are trying to
> accomplish.
>
> John
>
>
>
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Re: [Emc-users] FPGA arty --> FPGA communication hub, server --> PCI Express cards

[Philipp Burch]

Hi all!

On 21.10.2017 22:08, Gene Heskett wrote:
> [...]
> 
 I have no idea what is available for PC level hardware to do SPI
 communications though nor if that rate is fast enough for what you
 want
> 
> I've not been able to find anything in the way of pci or pci-e cards for 
> a pc. And even then, the length of cable will kill quite a bit of speed.
> 
> The cable from the pi to the 7i90's 26 pin header is about an inch long.
> 
> [...]

Let me just chime in regarding this. I'm currently doing just this PCI
Express interface card:
https://hb9etc.ch/hg/pcie_fpga_card/

It is fully open source (EAGLE schematics and PCB layout is in the
hardware folder) and designed to allow for the creation of custom
interface cards. That is, the board contains an Altera Cyclone IV GX,
which has an integrated PCI Express controller, together with the stuff
to get the FPGA up and running (supplies, config memory, etc.). 40 FPGA
I/Os are routed to a 2mm pin header at the edge of the board, designed
to be mated with an application card, which could then contain just
about any type of interface needed (as long as the pin count and FPGA
resources allow). With the application card plugged in, the whole
assembly will make up a standard PCI Express x1 card, either low or
standard profile. The application card can then be designed much more
easily, a 2-layer PCB will probably be fine usually.

The current state of the project is that the schematic and layout are
mostly finished, but need a thorough review and some cleanup. A simple
FPGA design is available to test if the pin connections are reasonable.
I expect that I will order the first few prototype PCBs in November, to
get something to play with.

Regards,
Philipp



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Re: [Emc-users] FPGA arty --> FPGA communication hub, server --> PCI Express cards

[Gene Heskett]

On Saturday 21 October 2017 16:59:08 Philipp Burch wrote:

> Hi all!
>
> On 21.10.2017 22:08, Gene Heskett wrote:
> > [...]
> >
>  I have no idea what is available for PC level hardware to do SPI
>  communications though nor if that rate is fast enough for what
>  you want
> >
> > I've not been able to find anything in the way of pci or pci-e cards
> > for a pc. And even then, the length of cable will kill quite a bit
> > of speed.
> >
> > The cable from the pi to the 7i90's 26 pin header is about an inch
> > long.
> >
> > [...]
>
> Let me just chime in regarding this. I'm currently doing just this PCI
> Express interface card:
> https://hb9etc.ch/hg/pcie_fpga_card/
>
> It is fully open source (EAGLE schematics and PCB layout is in the
> hardware folder) and designed to allow for the creation of custom
> interface cards. That is, the board contains an Altera Cyclone IV GX,
> which has an integrated PCI Express controller, together with the
> stuff to get the FPGA up and running (supplies, config memory, etc.).
> 40 FPGA I/Os are routed to a 2mm pin header at the edge of the board,
> designed to be mated with an application card, which could then
> contain just about any type of interface needed (as long as the pin
> count and FPGA resources allow). With the application card plugged in,
> the whole assembly will make up a standard PCI Express x1 card, either
> low or standard profile. The application card can then be designed
> much more easily, a 2-layer PCB will probably be fine usually.
>
> The current state of the project is that the schematic and layout are
> mostly finished, but need a thorough review and some cleanup. A simple
> FPGA design is available to test if the pin connections are
> reasonable. I expect that I will order the first few prototype PCBs in
> November, to get something to play with.
>
> Regards,
> Philipp

Sounds like it might be Ok Philipp.  Make some more noise here when the 
beta is fit to ship.

Cheers, Gene Heskett
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 soap, ballot, jury, and ammo. Please use in that order."
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Re: [Emc-users] FPGA arty --> FPPGA communication hub, server (real time communication)

[Erik Christiansen]

On 21.10.17 20:47, Nicklas Karlsson wrote:
> > You do want isolation between the high voltage motor and the digital
> > controller.  But if you already have this you don't need another layer.
> 
> Yes, I forgot for some reason I got depressed and didn't thinkg about
> adding this isolation barrier.

If you use a little RS485 Tx/Rx chip at each end, then that'll absorb 7v
of ground offset without further ado. The DS3695A is a bit current
hungry, and is only half duplex. More suitable would be something like:

SN65LBC180P Full duplex   5 mA, 30 nS pulse width, No Enables, 8-pin
(=> good to 10 Mb/s)

Balanced transmission between modules reduces EMI, and increases EMI
tolerance. Termination is 120 ohms - dead simple to use.

Erik

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Re: [Emc-users] FPGA arty --> FPPGA communication hub, server (real time communication)

[Nicklas Karlsson]

On Sun, 22 Oct 2017 17:37:40 +1100
Erik Christiansen  wrote:

> On 21.10.17 20:47, Nicklas Karlsson wrote:
> > > You do want isolation between the high voltage motor and the digital
> > > controller.  But if you already have this you don't need another layer.
> > 
> > Yes, I forgot for some reason I got depressed and didn't thinkg about
> > adding this isolation barrier.
> 
> If you use a little RS485 Tx/Rx chip at each end, then that'll absorb 7v
> of ground offset without further ado.

Yes balanced signal RS485 is good. I changed to isolated gate driver and then 
there is no need for isolation on SPI. Then distance is longer or network 
larger I could add an Ethercat module or use micro controller with builtin 
Ethercat.

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Re: [Emc-users] FPGA arty --> FPPGA communication hub, server (real time communication)

[Erik Christiansen]

On 22.10.17 10:44, Nicklas Karlsson wrote:
> On Sun, 22 Oct 2017 17:37:40 +1100
> Erik Christiansen  wrote:
> > If you use a little RS485 Tx/Rx chip at each end, then that'll absorb 7v
> > of ground offset without further ado.
> 
> Yes balanced signal RS485 is good. I changed to isolated gate driver
> and then there is no need for isolation on SPI. Then distance is
> longer or network larger I could add an Ethercat module or use micro
> controller with builtin Ethercat.

Yup, RS485 will do 1.2 km in one hop, but it won't do anywhere near 10
Mb/s on that length, so you'd need repeaters, e.g. a pair of sn65lbc179
chips for each full duplex hop.

Some RS485 chips will do over 60 Mb/s, but then you'd need a lot more
repeaters for long distances.

There are RS485 chips with low input loading, allowing up to 256 nodes
on a multipoint bus. That'd be a big machine shop too, and might warrant
a second serial bus, or more, for unlimited node count.

Erik

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