Hi,

How can I change I2C baud rate permanently?

Default is 400kHz.

I tried:
sudo modprobe i2c_bcm2708 baudrate=100000
sudo bash -c "echo options i2c_bcm2708 baudrate=100000 > /etc/modprobe.d/i2c.conf"

But this doesn't work. After reboot, baud rate is set to 400kHz again.

Thank you.

BR
Zdenko.

Hi Zdenko,

you need to change this in:

/etc/init.d/codesyscontrol

snippet:

        make_mknod
        killall codesyscontrol.bin > /dev/null;
        export PlcConfigFile=/etc/CODESYSControl.cfg
        echo bcm2708_i2c.0 > /sys/bus/platform/drivers/bcm2708_i2c/unbind
        echo 400000 > /sys/module/i2c_bcm2708/parameters/baudrate
        echo bcm2708_i2c.0 > /sys/bus/platform/drivers/bcm2708_i2c/bind

BR
Edwin

Thank you Edwin! It works .

BR,
Zdenko.

Hello
I'm trying to change the i2c baud rate to 100kHz following the example above. I have copied the code in to the "codesyscontrol" file but when restarting the pi, codesys does not work.
Is this how the change was intended? see attached picture.

Thank

Hi,

it looks ok.

You don't have to copy anything.
Just change parameter in /etc/init.d/codesyscontrol:
echo 400000 > /sys/module/i2c_bcm2708/parameters/baudrate
to:
echo 100000 > /sys/module/i2c_bcm2708/parameters/baudrate

and save file, then do reboot.
It should work.

Best regards,
Zdenko.

Hi,

did the location of

echo 400000 > /sys/module/i2c_bcm2708/parameters/baudrate

moved?

can't find it anymore in

/etc/init.d/codesyscontrol

BR Stefan

Originally created by: carlos.rivera

Stefan2 hat geschrieben:
Hi,
did the location of

echo 400000 > /sys/module/i2c_bcm2708/parameters/baudrate

moved?
can't find it anymore in
/etc/init.d/codesyscontrol
BR Stefan

Stefan were you be able to change the baudrate at the end? does anyone knows where to change it for the new raspberry. I can find /etc/init.d/codesyscontrol but cannot see this line echo 400000 > /sys/module/i2c_bcm2708/parameters/baudrate. Thank you.

Hi,
we have removed it,
it is more feasible to set it in /boot/config.txt as RASBIAN offer to do.

BR
Edwin

Hi Edwin,

thanks for Reply.

I'll check /boot/config.txt for that.

BR Stefan

Originally created by: carlos.rivera

Edwin Schwellinger hat geschrieben:
Hi,
we have removed it,
it is more feasible to set it in /boot/config.txt as RASBIAN offer to do.
BR
Edwin

Thanks so much Edwin. It worked.