I've had a problem with the yellow lightning flash appearing on my PD4 screen. I think I've resolved this now but it has me wondering - what is the Pi4 measuring when the lightning flash is displayed? Is it the 5.2v supply to the Pi4 board or is it the 3.3V produced by the Pi4 on-board regulator? (I had suspected that some of my external circuitry may have been pulling down the 3.3V line).
73, Russ.
RasPi 4 under-voltage indicator
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radiogareth
- Posts: 1370
- Joined: Wed Jan 06, 2016 9:46 am
Re: RasPi 4 under-voltage indicator
I'm sure someone will know but with a bit of digging you can find the RPI circuit diagrams on the RPi foundation website, at least you used to be able to....
Gareth
Gareth
Re: RasPi 4 under-voltage indicator
Russ
To start with you need 5v minimum on pins 2 and 4 of the GPIO.
That will eliminate any losses in the connector if you are using the USB-C power socket. Personally, I prefer to wire the 5v supply direct to the GPIO pins. Much more reliable.
However, if you are drawing more than 50mA from the 3.3v supply pins you may be in trouble. The only documentation from the Foundation relates to current from all of the GPIO pins, not the 3.3v supply, so the limit may apply.
Clive G3GJA
To start with you need 5v minimum on pins 2 and 4 of the GPIO.
That will eliminate any losses in the connector if you are using the USB-C power socket. Personally, I prefer to wire the 5v supply direct to the GPIO pins. Much more reliable.
However, if you are drawing more than 50mA from the 3.3v supply pins you may be in trouble. The only documentation from the Foundation relates to current from all of the GPIO pins, not the 3.3v supply, so the limit may apply.
Clive G3GJA
Re: RasPi 4 under-voltage indicator
Thanks Gareth & Clive. I now have a mini voltmeter on the front panel of my PD4/Langstone and I can switch between the 5.2V input and the 3.3V output. If the gremlin strikes again, the meter should provide some insight.
73,
Russ.
73,
Russ.