Fan Control

A utility ‘FanCon’ to control fan speed according to CPU temperature has been uploaded to !Store.

It expects an EMC 2101 chip on the IIC bus and will display a rolling chart of the processor temperature and demanded fan speed over the last ten minutes.

Testing on the compute module 4 shows the following:

It adjusts gracefully if IIC does not acknowledge from address &4C, or if MakeDraw has not been seen, or if the SWI ‘CPUClock_ReadTemperature’ is not available or if the ‘Portable’ module is not present.

Fan Control updated to version 1.06 and now includes an explanation of how to provide the necessary hardware – an Adafruit EMC2101 board and, of course, the fan. Software available from !Store.

This version is no longer dependent on MakeDraw and uses a pre-built Draw file to show the graphical data with relevant data poked in to the right places in the Draw file which is then displayerd.

It is dependent on CPUClock to provide the necessary SWIs to read the processor temperature.

On a CM4 running at 1500MHz (on a Waveshare Mini-A IO board with a 5V fan) the temperature builds up slowly over the course of about 4 minutes from 41°C to 46°C at which point the fan starts at slow speed automatically and over the course of about 1 minute brings the temperature back down to 40°C and the fan stops automatically. At slow speed you can barely hear the fan. This cycle then repeats.