How can the iPi be safely powered off without processor or SD card damage?

• g

  graham

  10/12/20, 8:53 AM

  How can the iPi be safely powered off without processor or SD card damage?

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• CL

  CHENGYU LEE

  10/12/20, 9:06 AM

  Hi Graham, there are several ways to do that.

  One way would be to use supercaps on the main 5Vdc input and use a GPIO to detect a low voltage.

   

   

  There are several solutions already online that were created for the RPI, only small adaptations would be needed to bring this to the I-Pi SMARC by using the same 40 pin-header

  

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• g

  graham

  10/12/20, 9:23 AM

  @CHENGYU LEE 

  Thank you for that circuit.

  WE actually already have a rather elaborate circuit that caters for other contingencies too, such as intermittent power outages that leave the supercaps depleted, in which case we wait for them to charge before turning the Pi back on. I have attached a flowchart. I happen to have a processor on the board connecting the Pi to my target instrument, so this is easy

  My question was: is there already some built-in protection in the IPi-SMARC making this unnecessary?

   

  My scheme needs a signal from the Pi indicating it is running. Is this avaliable on the Ipi? When the RPi shuts down with power still supplied, the output pins retain their states. Is this the case with the Ipi or do they go Hi impedance? I need to know when the orderly shutdown has completed so I can safely cut power.

  I appreciate your help. Graham

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