Automatic Cooling Fan on Pi

[Vaakkux]

I just bought a small fan for the raspberry pi. However I only want it to run after it exceeds a certain temperature.

Is it possible to do this either as a python script or C program. As if so how do I use the GPIO pins on either of these languages?

[tqhien]

You can get cpu temperature with the device virtual filesystem, like this (python) :

Code: Select all

    try:
        tfile = open('/sys/class/thermal/thermal_zone0/temp')
        t = tfile.read()
        temperature = float(t)/1000
        tfile.close()
    except:
        pass

then test temperature and trigger your fan (think about hysteresis so the fan does not flicker on/off around the threshold temp)

[pcmanbob]

If you have never used the gpio with python a good starting point would be the physical computing with python guide on raspberrypi.org

https://projects.raspberrypi.org/en/pro ... -computing

if you just want help with connecting your fan to the gpio there are plenty of examples on the web and on this very forum.

https://www.google.com/search?q=connect ... =firefox-b

[6by9]

Why not let the kernel do it for you? There's already the required device driver and DT overlay available.
https://github.com/raspberrypi/linux/bl ... EADME#L571
Add:

Code: Select all

dtoverlay=gpio-fan,gpiopin=12,temp=55000

to /boot/config.txt and gpio 12 should become active when the processor hits 55degC.

Use a standard transistor drive to connect the GPIO to the fan.