Ideal temperature

Linux for blind general discussion blinux-list at
Sun Nov 21 15:01:28 UTC 2021


On 2021-11-21 09:14, Linux for blind general discussion wrote:
> Hello,
> and what about turning off and on the cooling? What about writing
> script to automatically turn on and off the cooling when is needed or

My Raspberries run UEFI which takes care of all this. The only
requirement is to use such a fan which is pwm controllable. Such fan
has three leads. One for supply current, one for ground and the third
for control. There is no need for any scripting in this case.

> some script to turn on and off the cooling by key binding or command?
> Is it possible? I have Monitor toggle script to turn off and on the
> screen. Is it possible to do with cooling?

If you don't use UEFI but vanilla uboot then you need to take care
of turning the aforementioned controllable fan on and off using one
of the GPIO's. If you are running Raspberry OS it should have all
the required libraries, bindings, scripts, etc. already. IMO the
GPIO Raspberry OS uses by default is not the best choice since if
memory serves correctly it uses one of the serial ports for control.

If you are not using a fan which has a control lead then you would
need to hack together such a circuit which turns on your fan power
line. You can't power normal fan directly from GPIO pins. First,
voltage level on GPIO pins is 3.3V. Second, the GPIOs aren't able to
source enough current to power a normal fan. If you connect normal
fan directly to GPIO pins you'd blow the corresponding SoC gates.


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