Raspberry Pi 5 official cooler/fan control

[pik33]

I started to play/learn the environment using a rpi5 with original cooler. The cooler is running at full speed and makes unnecessary noise.
Is there a function/config/cmdline setting to control it?

[rsta2]

You have to add the class CCPUThrottle (from <circle/cputhrottle.h>) as a member of CKernel and to add the following options to cmdline.txt to control the fan of the RPi 5: gpiofanpin=45 socmaxtemp=60 socmaxtemp= gives the SoC temperature, at which the fan starts to rotate. Please note, that this is not using PWM, the fan is fully on or off.

[pik33]

I didn't manage to silence the fan this way. Maybe I did something wrong. I am still a novice in C++, going from Lazarus/Freepascal/Ultibo

I managed to silence the fan writing directly to the pin:

#include <circle/gpiopin.h>

CGPIOPin fan (45,GPIOModeOutput);
fan.Write(1);

---

There is a comment in cputhrottle.h that says

/// \note If the cmdline.txt option "gpiofanpin=" is used, this class controls a GPIO fan\n
/// not the CPU clock rate.

Does it mean I can control the fan OR the CPU speed but not both?

[rsta2]

You could try the sample/26-cpustress, which includes the class CCPUThrottle, with the file cmdline.txt on the SD card with this contents in the first line:

gpiofanpin=45 socmaxtemp=75

On the RPi 5 the CPU speed can only be set manually by calling SetSpeed(), when the fan is enabled. Then the class CCPUThrottle only manages the fan, not the CPU speed.