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[Solved / Archived] Auto startup after 5V power loss (Witty Pi 4 mini)

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(@eagleshot)
Posts: 32
Eminent Member
Topic starter
 

If the low and recovery voltage are set, it says the following in the manual: "Witty Pi will shut down your Raspberry Pi if input voltage is too low. Once this happens, Witty Pi will monitor the input voltage during the sleep and will turn on your Raspberry Pi when input voltage gets higher than recovery voltage threshold"

However it is unclear to me what happens if the 5V input also looses power. Will the Witty Pi reboot if the 5V power fails before the low voltage treshold is reached after 5V is restored and the recovery voltage is surpassed?

 

Thanks for your feedback!

Regards Eagleshot

1698050623-Screenshot-2023-10-23-at-10-33-09-WittyPi4Mini_UserManualpdf.png
 
Posted : 23/10/2023 10:43 am
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(@admin)
Posts: 444
Member Admin
 

Please notice the 5V input is different than VIN (input voltage) in Witty Pi. Usually you can only choose one of them to power your Witty Pi + Raspberry Pi. If you choose VIN, then the voltage needs to go through a DC/DC converter and eventually feeds 5V to the 5V input.

For Witty Pi 4 Mini, there is no DC/DC converter on board. Without soldering a DC/DC converter on it, the VIN pin can only be used to monitor an external voltage and turn off/on the device accordingly (after setting I2C register #41, I2C_CONF_IGNORE_POWER_MODE to 1), and can not be used to power the device.

With that said, if the 5V input is cut, the whole device will immediately go off because no power supply is powering the device. If 5V input is restored, wether your Pi will be turned on automatically depends on the "Default state when powered" option in software, as mentioned on page 15 in the user manual.

 
Posted : 23/10/2023 11:43 am
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