Raspberry Pi 4 with Mesa 7c81

1. G540 firmware is not appropriate for your breakout, you should use 5ABOB
firmware (unless you are connected to a Gecko G54 step drive)
(ironically this was already loaded in the as-shipped 7C81)

2. The other errors look like LinuxCNC was not built with the correct permissions
(If built from source did you run 'sudo make setuid' after 'make' ?)

It looks like I have created the problem myself. I didn't know about the right firmware and I was just following this thread without realizing that I have different hardware. In the support software zip file, there are two 5ABOB configs. 7c81_5abobx2d.bit and 7c81_5abobx3d.bit
Which one should I use? and what is the difference between them?
And what board and firmware will I need to select in PNCconf? 

I don't remember running anything like "sudo make setuid'. I downloaded the SD card image from www.linuxcnc.org/iso/linuxcnc-2.8.1-pi4.zip which already has linuxcnc on it and wrote the image file on SD card. I'm using a RPi 4B

Its a bit tricky because you need to specify G540 for pncconf (because pncconf does not support the 5ABOB) but use 5ABOB firmware on the 7C81 to match your BOBs pinout

There is no difference in the 5ABOB firmwares is you only have one BOB
(one supports 2 BOBs the other supports 3)

I am upgrading a 4-axis milling machine that works with MACH 3 and two parallel ports. I am going to use a raspberry PI 4 with a 7c81 that I already bought and I already have them working. The team has a BOB like the one in the photo and a C10 card with which it handles an MPG. The BOB uses pins 2 and 3 to control the spindle CW and CCW, pin 1 as a PWM generator for spindle speed control. Pin 14 is used as a charge pump generator that is controlled by the BOB. Pin 16 and are used to activate the motor drivers and pin 17 to enable the C10 card, inputs 10, 11,12,13 and 15 are used for the limit switches, Estop and probe and pins 4, 5,6,7,8,9, to control the motors of the X,Y,Z axes. C10 is used as inputs, pins 3 to 15 as inputs to an MPG 2, and pins 1,14,16,17 as outputs. Pins 1 and 14 are used for control of the lubrication and cooling pumps. and pins 16 and 17 control the motor of axis A. For this configuration I thought that none of the BIT files available for the 7c81 card would work for me. Could you help me with a firmware that could be adapted to my needs. 

The 7c81_c11gx2d.bit is correct for a C11g
(at least it matches CNC4PCs manual)

In the C11G manual, DB25 pin 14 = PWM
and DB25 pins 2 and 3 are step/dir outputs
and the relay pins are 1 and 17. This matches
the firmware pinout.

I don't think that firmware works for me, this would be the configuration of the 7c81:


Pin# I/O
P1-01/DB25-01 0 PWM SPINDLE
P1-02/DB25-14 1 CHARGE PUMP
P1-03/DB25-02 2 CW SPINDLE
P1-04/DB25-15 3 ESTOP
P1-05/DB25-03 4 CCW SPINDLE
P1-06/DB25-16 5 ENABLE X
P1-07/DB25-04 6 STEP X
P1-08/DB25-17 7 ENABLE C10
P1-09/DB25-05 8 DIR X
P1-11/DB25-06 9 STEP Y
P1-13/DB25-07 10 DIR Y
P1-15/DB25-08 11 STEP Z
P1-17/DB25-09 12 DIR Z
P1-19/DB25-10 13 LIMT X
P1-21/DB25-11 14 LIMT Y
P1-23/DB25-12 15 LIMT Z
P1-25/DB25-13 16 PROBE
IO Connections for P2+Serial -> 7C81_1
Pin# I/O
P2-01/DB25-01 17 OIL PUMP
P2-02/DB25-14 18 PUMP MIST
P2-03/DB25-02 19 ENCODER A
P2-04/DB25-15 20 OUT
P2-05/DB25-03 21 ENCODER B
P2-06/DB25-16 22 STEP A
P2-07/DB25-04 23 JOG X
P2-08/DB25-17 24 DIR A
P2-09/DB25-05 25 JOG Y
P2-11/DB25-06 26 JOG Z
P2-13/DB25-07 27 JOG A
P2-15/DB25-08 28 1
P2-17/DB25-09 29 0.1
P2-19/DB25-10 30 0.01
P2-21/DB25-11 31 ESTOP MPG
P2-23/DB25-12 32 IN
P2-25/DB25-13 33 IN

Do you have some documentation for your breakout?

That does not match a CNC4PC C11G

drive.google.com/file/d/1TW8bCW-9kMDqs1z...5g/view?usp=drivesdk

Seems to need a login to view

I send the file to you email.