Toggling of GPIO4_IO23 on humming board pulse


I want to toggle the gpio pin 119 attached in screen shot. But not able to toggle when i see on oscilloscope/multimeter. Can you please correct me if i am wrong?

I followed the below steps to toggle it.

  1. echo 119 > /sys/class/gpio/export
  2. echo out > /sys/class/gpio/gpio119/direction
  3. echo 1 > /sys/class/gpio/gpio119/value
  4. echo 0 > /sys/class/gpio/gpio119/value


What BSP image are you running?


Please see the metioned screen shot for Linux BSP version. And i have followed the steps mentioned in link for yocto

Thanks & Regards,
Screenshot from 2023-10-10 15-03-43

and what revision of the carrier are you using? The pin connected to the mikrobus changed between rev 2.3 and rev 2.5 carriers

May i know how to find the rev. I have rev 2.2, 2.3 & 2.5 downloaded from this link. And we are following rev 2.5.

You should be able to check the SKU, but otherwise it is silk screened onto the board underneath where the SOM is mounted.

Unable to find the rev. Attached board underneath image for your refernce. Can you please help me.

It is on the top of the board in between the SOM connectors. You need to remove the SOM to see it.

Hi Jnettlet. Sorry for late response. My humming board pulse(imx8mplus) is rev 2.5.
Can you please tell how to toggle gpio on mikrobus.

Rev 2.5 has the SAI2_RXD pin connected to SAI3_RXD of the iMX8MP SOM. This pin is also shared with the wm8904 audio so they can’t be used at the same time. To use this pin as a GPIO you need to remove it from the &pinctrl_sai3 group and add it to the &pinctrl_hog group as a GPIO. It should be GPIO 158.