Unable to set fan speed

I'm manually installing the software on a pre-build StromPi 3 and case on a Raspby 4 B.The fan_control_en.py is unable to set the speed of the fan (the German one too). 

The jumper on the little board is set on the PWM-pins. Configuration is as follows:

Time: 15:11:04
Date: Sunday 21.11.21
StromPi-Output: mUSB
StromPi-Mode: mUSB -> Battery
Raspberry Pi Shutdown: Enabled
 Shutdown-Timer: 30 seconds
Powerfail Warning: Disabled
Serial-Less Mode: Disabled
Power Save Mode: Disabled
PowerOn-Button: Enabled
 PowerOn-Button-Timer: 30 seconds
Battery-Level Shutdown: 10%
Powerfail-Counter: 45
PowerOff Mode: Disabled
WakeUp-Alarm: Disabled
 Alarm-Mode: Time-Alarm
 Alarm-Time: 00:00
 Alarm-Date: 01.11
 WakeUp-Alarm: Monday
 Weekend Wakeup: Enabled
 Minute Wakeup Timer: 30 minutes 
PowerOff-Alarm: Disabled
 PowerOff-Alarm-Time: 00:00
Interval-Alarm: Disabled
 Interval-On-Time: 00 minutes
 Interval-Off-Time: 00 minutes
Wide-Range-Inputvoltage:  not connected
LifePo4-Batteryvoltage: 3.33V [100%] [charging]
microUSB-Inputvoltage: 5.16V
Output-Voltage: 5.104V
Firmware Version: b'v1.72c\n' 

The program asks for GPIO-pin 2, but as far as I could see, the jumper on the little board is connected to GPIO3. Tried both settings, but none of them work.

I even tried to set the GPIO's manually with raspbi-gpio, but that does not work either. The fan keeps running  more or less on half speed (I think).

Uncommented the print on line 36, which outputs:

40.407C, 0
40.407C, 0
39.433C, 0


Still, the fan runs.

Any ideas for things or tests I could try?

John Heijens

21.11.21 15:43

Did some measurements on the fan-control pcb. Setting GPIO2 high or low (confimed it by measuring the output voltage) does not matter. The voltage on the PWM-pin (the most left one) stays on approx. 3.3V

Could it be a faulty fan-control pcb? How/where can I aquire another one for testing? I think it's a bit rediculous to return the whole package if the problem appears to be in this little Fan-control pcb...

John Heijens

23.11.21 19:57

Hello John,

the fan is controlled with the GPIO2, this is also the SDA pin of the I2C interface. This could be a problem if you are using the I2C interface for anything else.

If this is not the case, your fan-control pcb is probably defective. 

Please contact our support to request an exchange of the pcb

Email: service@joy-it.net

Ticket system: http://support.joy-it.net

Telephone: +49 (0)2845 9360-50


Best regards

Tim (Joy-IT)


25.11.21 17:02