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hello,
I'me powerimg a pi zero /witty pi mini by a small solar unit with an lead acid battery. I'm monitoring the battery voltage via witty pi mini. If voltage is below 12.4V, it should perform a shutdown in order to save battery life. Above 12.8V it should boot up again. This all works somehow, but often fails. Right now the voltage is below 12V, even if I do repeated measurements, and it doesn't shut down for some reason.
>>> Current temperature: 17.50°C / 63.5°F >>> Your system time is: Tue 24 Oct 2023 18:52:35 CEST >>> Your RTC time is: Tue 24 Oct 2023 18:52:34 CEST >>> Vin=11.87V, Vout=4.75V, Iout=0.38A Now you can: 1. Write system time to RTC 2. Write RTC time to system 3. Synchronize time 4. Schedule next shutdown [?? 21:00:00] 5. Schedule next startup [?? 05:00:00] 6. Choose schedule script 7. Set low voltage threshold [12.4V] 8. Set recovery voltage threshold [12.8V] 9. View/change other settings... 10. Reset data... 11. Exit What do you want to do? (1~11)
help appreciated
thanks u
Posted : 24/10/2023 7:04 pm
You didn't mention, but it seems to be a Witty Pi 3 Mini.
The firmware will check some conditions before doing the low-voltage shutdown. You can check how it is done here:
https://github.com/uugear/Witty-Pi-3/blob/master/Firmware/WittyPi3/WittyPi3.ino#L127
If the prevous shutdown was also due to low voltage, it will not work.
Witty Pi 3's firmware doesn't provide any option to configure this behavior. If you want to change it, you will need to modify the firmware and upload to Witty Pi 3 Mini by yourself.
Witty Pi 4's firmware provides I2C_CONF_IGNORE_POWER_MODE and I2C_CONF_IGNORE_LV_SHUTDOWN options for this.
Posted : 25/10/2023 4:44 pm
Topic starter
yes, it's a witty pi 3 mini. What the reasoning that it can't shutdown/startup on subsequent low voltage / recovery voltage events? I don't get it. Anyway, I can confirm, from my workshop tests with a wittypi 4 mini, that it works the way I've expected. Just have simulated many low / recovery voltage event in a sequence and it seems to behave fine.
Posted : 25/10/2023 8:35 pm
It most probably was to avoid shutting down during the recovery from pervious low-voltage shutdown. This part was not well designed, and that's why we make change in Witty Pi 4.
Posted : 26/10/2023 8:32 am