I found the simple_pwm.py file in my jetson-gpio folder. Using the jetson-io.py I activated all 3 pwm pins: pwm1, pwm5, pwm8. Now it actually works; in fact, I modified the code and I am now running different PWM frequencies simultaneously on two pins = 32, 33.
So, inspired by your forum help I am now using PWM, i2c, and SPI, although not tested all together yet.
I thus consider this thread as SOLVED, thanks.
However, one issue is still outstanding, i.e., the fast data acquisition through a fast function interrupt pin to measure 32-bit radiation data, as mentioned in my entry of a few hours ago. Can you suggest a NVIDIA datasheet solution reference, perhaps?
I am very happy with your help, thanks again.