Linuxcnc 2.9.2 and 2.93 images for Raspberry Pi 4b & 5

To turn on i2c

edit as superuser /boot/broadcom/config.txt and uncomment the lines relate to i2c.

then edit as superuser /etc/modules and either add i2c-dev or uncomment if it is commented out

reboot

That will get i2c up and enabled

I was able to enable i2c, but the instructions say use “sudo i2cdetect -y 1”, 1 doesn’t seem to exist for me, I can only detect 11 and 12 and neither show the 0x36 address.
I have confirmed that the pins are making good contact, so bad connection is ruled out.
Could it be the kernel configuration?

I'm working on a Rpi5 with an image I built myself from rodw's image builder

This is my kernel.
Linux raspberrypi 6.1.69-rt21 #1 SMP PREEMPT_RT Fri Jan 17 10:39:48 AEDT 2025 aarch64 GNU/Linux

Before I finalised my post I checked running by running
As I have nothing connected I got this:
sudo i2cdetect -y 1
0 1 2 3 4 5 6 7 8 9 a b c d e f
00: -- -- -- -- -- -- -- --
10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
70: -- -- -- -- -- -- -- --


What does show ?

/dev/i2c-1 /dev/i2c-11 /dev/i2c-12

Too hard to edit

[ls -la /dev/i2c*[/code]

Would be good to see permissions, not that should affect sudo.

It’s only showing 11 & 12, I can’t get 1 to show.

I’m pretty sure I’m using the latest kernel though.
6.6.44-rt39

Did you run the commands I suggested and post the output ?

What RPi are you using ?
What Linuxcnc img are you using ?

I’m using a raspberry pi 5 8gb with the latest 2.93 image that’s linked on the first page of this thread. I’ve attached a screen shot of what I’m getting when run the commands. 

Ok it was a typo I made, but if you tried to edit the file it should not of existed.

as superuser edit /boot/broadcom/config.txt & change the line from

#dtparam=i2c_arm=on
to
dtparam=i2c_arm=on

Then reboot.

hello,I can install on both raspberry pi5 4gb and 8gb but the new 16gb I bought gives an error. What is the reason for this?

I think the 16gb has historically not been good for linuxcnc