We have Pi 4 gateways in small pump kiosks, each reading a flow meter and two pressure transmitters and sending to Hermetry. Three of them reboot at random times, maybe once or twice a week, usually in the afternoon. No pattern in the logs except that kernel messages before the reboot sometimes mention undervoltage.
Two questions: how does the Pi actually know it isn’t getting enough power, there’s no ADC on the 5 V rail that I know of? And can I get that state into Hermetry so I get an alarm before the reboot, instead of finding out from a gap in the charts?
On my desktop Pi a little lightning bolt shows up in the corner when the supply is bad, so it definitely knows somehow.
There’s a voltage supervisor on the board that trips at roughly 4.63 V and the firmware latches it. You read it with vcgencmd get_throttled.
Is that logged anywhere permanently, or only while it’s happening?
- You must be logged in to reply to this topic.
Join the conversation
Sign in to ask and answer, like helpful posts and mark the reply that solved your problem. Every contribution earns points and levels.