jamesh wrote: ↑
Thu May 17, 2018 2:20 pm
hippy wrote: ↑
Thu May 17, 2018 12:51 pm
Milliways wrote: ↑
Thu May 17, 2018 10:16 am
I agree with the Foundation engineers that the firmware should not be modified to work around hardware problems which may compromise operation.
The thing is, if one doesn't need any 5V out of the Pi, then it can be working perfectly with no risk of compromised operation even if the low-voltage warning appears.
Apart from the dramatically increased probability of, for example, SD card corruption and networking dropouts.
But apart from that, everything is fine. Yay!
The SD Card doesn't use 5V. The network doesn't use 5V.
If I design a board which uses a Power Management chip which reliably supplies 3V3, 1V8 and whatever other voltages are needed by that board and that works reliably right down to 4V then it's absolutely fine with any power supply down to 4V.
You can power that board with 4.2V with no problems. Everything works as expected. Nothing is being compromised.
If I choose to add a low voltage warning set at 4.6V that doesn't mean supplying with 4.2V is somehow now a risk, a hardware problem has been created, or operation is compromised in any way.
That's exactly how it is with the Pi 3B+ except the low-voltage warning has been included from the outset.
If the Power Management chip works reliably down to 4V, reliably puts out all voltages used by the board and its components down to 4V, how is anything compromised when the voltage drops below the low-voltage level but remains above that 4V ?
Nothing is compromised.
Yes, anything which could be connected and requires 5V can be compromised but if nothing is using that 5V then nothing can be.
I simply don't understand how it's so difficult to understand. It is exactly like a fuel level warning in a car. The light comes on well before the fuel runs out. It coming on doesn't mean it has to be stopped immediately and parked up, recovery called. It is simply a warning that fuel is below a certain level. As long as fuel is above the amount needed it is fine.
Unlike a car's fuel supply, a power supply can remain below the low voltage warning level but above the minimum level for reliable operation and not cause any problems indefinitely.
If everything which requires a voltage is getting the voltage it requires at the current it needs, how is running with the low-voltage warnings going to cause "dramatically increased probability of, for example, SD card corruption and networking dropouts" ?
Why would it ?