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Unfortunately my pi4 in the machine died. The 7c81 seems fine, i even reflashed the 7c81 with the right bitfile, just to be sure, no errors. So i switched to a pi5, but the previously working config gives me an error.


spi in the kernel config is activated.

Any ideas?

Honestly, I would just add a  leaded 620 Ohm pulldown
resistor on the back of the breakout card and not make
any further modifications.
 

so a stiff pulldown to fight the pullup of the mesa card for the inputs?

I am using 7c81_5abobx2d firmware with BOB boards on P1 and P2.

Edit:
I did a little bit of digging.
- The relay pin P17 is IO7 of the Mesa ports, which is on the edge of the pull resistor array. I could desolder the array and put it back on shifted by one to remove the resistor of the pin.
- On the BOB there is a 10k pullup array on the relay pin. but the signal comes through a via in the middle of the pullup resistor and the 74HC... I could cut the trace between the via and the resistor to remove the pull up on the BOB
- solder in a pulldown resistor on the BOB (if for whatever reason the flat cable between the Mesa and BOB gets bad).

The 7C81 only has the option of all pullups and all pulldowns
on its I/O ports.

Simplest solution would probably be to add a stiff pulldown (say 620 ohms)
on the relay I/O pin. There is a firmware option for fixed parallel port type I/O
but currently its global (not per port), This firmware makes the parallel port
output pins default to outputs instead of inputs at startup or watchdog bite
What firmware are you using?

Maybe a stupid question, but how do you use the relay on those cheap MACH3 BOBs with the 7c81?

For the inputs to work I need to enable the pullups on the 7C81.
But enabling the pullups makes the relay close as soon as the BOB is powered.

Ideally I would want the relay to be open until linuxcnc is started and I tell linuxcnc to close the relay.

But the relay closing by default due to the pullups makes it unusable, or did I miss something?

Any ideas ? No one has bothered.
Might be supported by the Litex infrastructure. The ethernet chip of that board is different to the one Mesa uses, so a driver would be at least one of the tasks.

Plenty of Spartan 6 Dev boards that are easier to use Hostmot2 (mesa fpga firmware sources) firmware with. I've had success with 7c81 setup, both SPI & SPP (parallel port) interfaces. Now experimenting with Ethernet.

Ok once you have the firmware going, the next step is designing & building the I\O, translation from 3.3v to 5v and then whatever your field voltage maybe.

At the end of the day it's just a little under what a Mesa board may cost, unless of course you're Down Under and shipping can almost double the cost of a 7i92.

Nah my images do work out the box, fark I can actually test them before releasing them in the wild, so far the zram issue has only affected one user. Which whilst I have wanted to put up a new image with the fix there has been push back.
The issue that seems to be with the RPi images is that users think that everything is the same as the images from Raspberry Pi, it's like they can't seperate the board from a particular OS.
The fact that I can run mine with either a 7c81 clone that I've put together myself or a Spartan 6 Dev board with an ethernet interface both running slightly modified hostmot2 firmware proves that it does work. Oh and the RPi platform is younger than the whole Linuxcnc project itself....
But an x86 platform is the best bang for buck, no 2 ways about it. You buy a PC and it's complete ready to go. An RPi5 will need a case, PSU a secondary board to run a NVMe drive or a SATA adaptor board if you want something more spritely than an SD card. The x86 platform is tried and true, it works, it's common, it's rugged and has been used it 54 billion installations by Tommy alone this month, as my estimates go.
The only advantage of the RPi platform is size, tho an Odroid H4 or the older H3 isn't much larger and maybe the SPI interface. The mini HDMI connectors are a pain. In saying that waveshare does do some nice boards that plugin to the existing HDMI, power and audio connectors to bring them out to the same side as the USB & ethernet, a nice NVMe adaptor and a aluminium case to suit.

There is a thread with a guy integrating a cm carrier board with a 7c81.
The RPi5 works but it's a very expensive option compared to an ex corporate PC. The only real advantage is size and that's about it. The RPi5 images work out of the box, but do require the zram fix mentioned in the big thread, it's not a game killer but can raise its head.
Having a RPi5 and 3rd Gen I5 running for testbeds the i5 is definitely the one I'd choose for a build.
For my mill I running a odroid H3 and can not fault it, this has been replaced by the H4.
As for pre-built control boxes, any that rely on the parallel port can be used with a 7i92 for an ethernet option or a 7c81 for SPI with a Raspberry Pi. Some of the issues I have with them is use of DB9 connectors for the Stepper motor connectors. Most of them are quite compact which raises issues of heat and airflow.
I prefer to build my own, lots of room for air flow, the ability to keep the mains and signal wiring well seperated, on side has all the mains, the other side has the low voltage signalling.
I guess if that isn't part of your skill set then an off the shelf control box might be the option if you have the funds.

As you're asking for an interface board I'm Gunna assume you have a 7c81 at hand.
The expensive route but most complete, reliable and expandle route would be a 7i76, not the ethernet version but a plain version that you connect via a ribbon cable. This will give you everything you need except the stepper drivers on board.
In all honesty as a preference I much prefer the "standard" type stepper drivers rather than the types used on the smaller desktop CNC toys and such.
Unfortunately as you've found out there's not a lot of breakout boards available that handle 24v signals, most will be a DIY thing.

Still for sale.

Hi,
only one 7c81, you tip has done the trick. Thank you!
but the next problem occured
The error changed to:
/intos.hal:88: parameter or pin 'hm2_7c81.0.7i77.0.1.analogout0-scalemax' not found

so checked this line in the old, working hal, without the 7i78, and its exactly the same. What does change here when i use 2 daughterboards?
Any Ideas?

EDIT:
i have also tried to change the channel number to 0:
hm2_7c81.0.7i77.0.0.analogout0-scalemax'
and 2 and 3

How many 7c81 are in use?
for one only, delete the line containing 1
addf hm2_7c81.0.read
addf hm2_7c81.1.read
Pretty sure this should only be used if you have 2 of 7c81, 0 and 1 there are enumeration for 2 of 7c81 not the add on cards, they do have their own enumeration after the model number, example:
hm2_7c81.0.7i77.0.0.input-07
First 7c81 that has the first 7i77 attached, first is always 0 with Mesa and LinuxCNC enumeration.
Had a look at your hal, there is more editing required, so it might be easier to make a new config with a single 7c81.

Hi,
thanks for your fast reply.
if you read in the hal, there is written :
addf hm2_7c81.0.read
addf hm2_7c81.1.read
for both cards
.0 is the 7i77 and .1 is the 7i78
I interpreted the documentation that it should be done like this.
Any advice how it is configured correctly?

HAL: ERROR: function 'hm2_7c81.1.read' not found
./intos.hal:16: addf failed


should be
hm2_7c81.0.read

Raspberry Pi 4 Model B Rev 1.2
Mesa 7c81
Debian GNU/Linux 12 (bookworm) 6.1.54-rt15 #1_RT Fri Nov 17 17:02:27 AEST 2023 aarch64

I installed LinuxCNC 2.9.3 from the linuxcnc ISO image a couple of years ago, and upgraded to 2.9.4 yesterday by:
$ sudo apt update  && sudo apt full-upgrade

I now have:
rick@raspi4:~$ dpkg -l | grep linux-image
ii  linux-image-bcm2711-rpi-4            6.1.54-rt15-1                           arm64        Linux kernel, version 6.1.54-rt15
rick@raspi4:~$ dpkg -l | grep linuxcnc
ii  linuxcnc-doc-en                      1:2.9.4                                 all          motion controller for CNC machines and robots (English documentation)
ii  linuxcnc-uspace                      1:2.9.4                                 arm64        motion controller for CNC machines and robots
ii  linuxcnc-uspace-dev                  1:2.9.4                                 arm64        PC based motion controller for real-time Linux

rick@raspi4:~$ uname -a
Linux raspi4 6.1.54-rt15 #1 SMP PREEMPT_RT Fri Nov 17 17:02:27 AEST 2023 aarch64 GNU/Linux

Is there a newer RT kernel then the one from 2023 ?
If so, how can I upgrade the kernel without having to reload the entire system from the latest ISO image ?

TIA,
Rick