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[Solved] Witty Pi 4 Monitor Voltage on XH2.54 While Powered On USB-C?

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(@goremaker)
Posts: 8
Active Member
Topic starter
 

Is it possible to use the voltage threshold monitoring on the XH2.54 connector while also powering the Witty Pi 4 from the USB-C connector?

 

So if I set the lower voltage threshold to 9v, and the voltage on the XH2.54 connector dropped to 0v, then the Witty Pi 4 would still be powered by the 5v at the USB-C connector and trigger a shutdown of the Raspberry Pi? Or is this not possible?

 
Posted : 11/01/2024 3:23 am
(@admin)
Posts: 203
Member Admin
 

This is not recommended for full-sized Witty Pi 4, which has DC/DC converter on board and it converts the voltage on XH2.54 connector to 5V and feed that 5V to the same trace as USB-C connector. Witty Pi has only one power channel, and if you connect two power sources to it at the same time, they may fight each other if the two "5V" are different.

Witty Pi 4 Mini however, can be used for this purpose, because it has no DC/DC converter on board and the voltage on VIN pin can be measured by ADC.

 
Posted : 11/01/2024 4:43 pm
(@goremaker)
Posts: 8
Active Member
Topic starter
 

Thank you!

The manual for the Witty Pi 4 Mini states that the threshold (min or max) can be set from 2v to 25v. Does that mean I can feed a 14v source directly to that VIN pin without damaging anything on the board?

 
Posted : 11/01/2024 6:49 pm
(@admin)
Posts: 203
Member Admin
 

@goremaker Yes. There is already a voltage divider on the board, and the actual voltage that feed to ADC is lower than 1.1V.

 
Posted : 15/01/2024 8:53 am
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