Sending PWM signal to pin 8

[librecomputer]

@Jobistober

Enabling this pin in raspi-config does nothing.

raspi-config’s overlay controls does nothing on our boards.

@Jobistober

I read through “How to Read and Control PWM Fan Speed on AML-S905X-CC” and it seems PWM is not sent to pin 8 at all.

You have to do software bit-bang PWM with pwm-gpio driver for pin 8. This will use the CPU to flip the GPIO to generate the PWM waveforms. The timing is not perfect and it uses CPU cycles but for fan control, it is sufficient.

Libre Computer Wiring Tool

To install via apt: sudo apt update sudo apt install libretech-gpio libretech-dtoverlay libretech-gpio To get a list of headers for your board: lgpio headers To get a list of the header pins for a header: lgpio header HEADER For getting the information for a pin number on the main GPIO header of the board: lgpio info PIN# For getting the information for a pin number on a specific header of the board: lgpio info HEADER PIN# For getting the libgpiod chip and line number for a pin on th…