Generating a pulse with M4 Core on Imx8 Mini

[Alirezah95]

Hi.

I'm trying to generate a pulse on a GPIO pin using M4 Core and I have built the M4 firmware for this purpose too and the pulse is being generated successfuly (I'm using uboot to load the firmware). Everything works as expected unitl the kernel boots up and then the pulse vanishes in the osciloscope. I've checked and confirmed that the code is still running correctly on the M4 core but it looks like the kernel has taken the ownership of GPIO, so the M4 core is not able to actually change the pin value. Is that right? If so how would I fix this? How would I prevent kernel from taking the ownership of GPIO so the pulses keep generating even after kernel boots up.

[Bio_TICFSL]

Hello,

M4 is low power microcontroller available for customer application:
• Low power standby mode
• IoT features
• Manage IR or wireless remote

Also one can look at below app notes describing M4 usage:

AN12225 How to Reduce SoC Power when Running M4 with A53 on i.MX8M
AN12195 Implement Low-Power Audio on i.MX8M

Regards

[Alirezah95]

So is it possible to generate pulses using m4 while the os is running?