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Pimoroni Fan SHIM Runs
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Pimoroni Fan SHIM Runs

by robert_b on Sat Jul 24, 2021 1:53 pm

I recently added a Pimoroni fan SHIM (part #4316) to my Pi4B, and noticed that it begins running immediately after I plug in the PS, and continues to run even after I perform a shutdown.

Is this normal behavior? If not, do I have a defective SHIM?

Under Configuration, Fan is Enabled, Fan GPIO is 13 (default), and Fan Temperature is 80 (default).

Running Raspbian buster, release 10.

Thanks for guidance!

robert_b
 
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Re: Pimoroni Fan SHIM Runs

by alphanumeric on Mon Jul 26, 2021 4:03 am

That's normal operation, the failsafe default state for the fan is ON. The fan control pin has to be pulled low to turn the fan off. If it's high or floating the fan is on. On boot up, before the fan daemon loads that pin will be floating so the fan turns on. Once the daemon loads its under temperature control. On shutdown that pin goes back to its default state and the fan turns on again. There is a modification you can make to the Fan Shim PC board to make the default state off. Once you do that, if has to be commanded on with software though.

https://forums.pimoroni.com/t/fan-shim- ... post/12169

alphanumeric
 
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Re: Pimoroni Fan SHIM Runs

by robert_b on Mon Jul 26, 2021 5:02 pm

Great info, thanks alphanumeric. I have a lot of reading to do now...

robert_b
 
Posts: 5
Joined: Sun Oct 28, 2012 3:01 pm

Re: Pimoroni Fan SHIM Runs

by alphanumeric on Tue Jul 27, 2021 3:25 am

I personally prefer the fan to be off when the Pi is shutdown. With that modification I can just press the button on the Fan Shim to shutdown, Pi turns off and fan turns off. Press the button again and Pi turns on and the fan is on / enabled. No having to unplug the power supply.

alphanumeric
 
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Please be positive and constructive with your questions and comments.