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Hello, we're using the Witty Pi 4 L3V7 in our design and wanted to check if it supports a backup RTC battery (like a coin cell) to keep the time even when the main battery is drained or removed.
Thanks
Nick
Posted : 06/06/2025 10:18 am
Witty Pi 4 L3V7 does not directly support an RTC backup battery. Its typical use case is to have the 3.7V battery always connected, because that battery can also be charged by the same board.
If you would like to add a backup battery, I am afraid you will have to power the whole 3.3V rail, which will power the MCU, RTC and temperature sensor together. If your backup battery is not re-chargable, then you will need a diode to prevent the 3.3V rail to charge it.
Posted : 06/06/2025 6:03 pm