BBS:      TELESC.NET.BR
Assunto:  Re: PI PICO W minimum voltage..
De:       The Natural Philosopher
Data:     Thu, 14 May 2026 22:52:43 +0100
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On 14/05/2026 22:27, Pancho wrote:
> On 5/14/26 22:17, The Natural Philosopher wrote:
>> On 14/05/2026 18:08, druck wrote:
>>> On 13/05/2026 14:06, The Natural Philosopher wrote:
>>>> On 13/05/2026 12:12, druck wrote:
>>>>> On 12/05/2026 14:04, The Natural Philosopher wrote:
>>>>>> I measure at the far end of the chain
>>>>>
>>>>> How? Multimeter, USB power measuring dongle, oscilloscope.
>>>>>
>>>> Sigh
>>>>
>>>> The Pi PICO W has three ADCs on board and one is connected directly
>>>> to VSYS by a voltage divider. I transmit that data every time the
>>>> device successfully activates.
>>>
>>> I'm not sure I trust something to measure it's own voltage, when it
>>> might be experiencing low voltage.
>>>
>> That is probably because you have not understood the first thing about 
>> how a PI PICO W is constructed.
>>
>> It has its own onboard buck/boost regulators and the ADC is driven 
>> from a stabilised 3V line
>>
>> The rest of the chip runs on a less well regulated 3.3V.
>>
>> The chip runs down to 1.8V
>>
>> The ADC is not set up to 'measure its own voltage' but that of the 
>> incoming voltage TO the chip.
>>
> 
> FWIW my rpi4 is able to give low voltage warnings, seemingly reliably.
> 
Yes. I have the thing back on the bench and have tested with an ammeter 
and a scope as well as voltmeter.
After several startups it blew a 200mA fuse in the ammeter . So short 
term peaks are a little over that. Well a good excuse to buy a much 
better digital meter then. I was already sick of the previous one, Ali 
express are giving the previous type away for free when part of another 
order...so that is what THEY were worth...

I did catch it in two fault modes, one was an oscillating low energy 
switch, which results in the PICO never being switched on, and the other 
was some kind of network issue that resulted in it never switching off.

Either might cause loss of connection and high battery drain.

Both have not been possible to reproduce reliably.

I've modified the code to hopefully eliminate the 'I am stuck trying to 
connect to a TCP socket' condition, which should not happen anyway.

The oscillation might be caused by a bad electrolytic, and cold

Its not reoccurred since testing on the bench


-- 
In theory, there is no difference between theory and practice.
In practice, there is.
-- Yogi Berra


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