what is the supply voltage that you fans require? Typ PC chassis fan i.e. is 12V.
You can ignored the TACH signal, you only need supply voltage (GND and whatever VCC your fans need) and PWM.
A PCA9685 comes handy for PWM, as you would only need 4 GPIO instead of 4. it is also my recommendation as a Pi4 has only 2 HW PWM. Yes, you can do SW PWM on any GPIO, but I would not do that for multiple reasons.
for controlling them you can use hwmon, but you will have to have your own overlay for the PCA9685. when using GPIO you can have multiple instances of https://github.com/raspberrypi/linux/bl ... verlay.dts
You can ignored the TACH signal, you only need supply voltage (GND and whatever VCC your fans need) and PWM.
A PCA9685 comes handy for PWM, as you would only need 4 GPIO instead of 4. it is also my recommendation as a Pi4 has only 2 HW PWM. Yes, you can do SW PWM on any GPIO, but I would not do that for multiple reasons.
for controlling them you can use hwmon, but you will have to have your own overlay for the PCA9685. when using GPIO you can have multiple instances of https://github.com/raspberrypi/linux/bl ... verlay.dts
Statistics: Posted by aBUGSworstnightmare — Mon Jan 19, 2026 6:02 am