[arm-allstar] Notes on under voltage problem

[Jim Darrough]

I did recently set my Pi up again, since I had the original system so 
tweaked that I couldn't ssh into it. As a result, I think that is the case.

I hadn't noticed the messages before then. I am using a 2 amp supply 
(wal wart) at the moment, but I HAVE ordered two new "Genuine" Raspberry 
Pi supplies. They are purty!

I haven't noticed any issues other than a bunch of errors about voltage. 
And I don't suspect I will.

73 Jim KI7AY


On 05/17/2018 04:53 PM, "Doug Crompton via arm-allstar" wrote:
> Jim,
>
>   Are you using the download image from hamvoip.org that was in the last
> month or so. That image now supports the 3B+ and is a latter kernel than
> the current update distribution. So if you downloaded the image in the last
> month or so the later image includes the low voltage message. We will be
> putting out that update from everyone (to the new kernel) soon. I suspect
> many will find they get the message with under-voltage supplies.
>
> I am not sure what the set point is for under voltage but just because you
> get the message does not necessarily mean your Pi will malfunction. The
> actual processor and peripherals run on other regulators from the 5V line -
> 3.3 and 1.2 volts. It is however a warning that could be eliminated with a
> proper supply.
>
>
> *73 Doug*
>
> *WA3DSP*
>
> *http://www.crompton.com/hamradio <http://www.crompton.com/hamradio>*
>
>
> On Thu, May 17, 2018 at 5:12 PM, "Jim Darrough via arm-allstar" <
> arm-allstar at hamvoip.org> wrote:
>
>> My setup is with a Pi 3B, not B+. WHen I was using an Adafruit 2.4 amp
>> power supply, no messages. Went back to a 1 amp power supply, messages came
>> back. I don't think the b+ actually causes the problem, but I can see where
>> it might draw more current. Voltage sag can occur (as Doug mentions) with
>> current that comes close to maximum on any device.
>>
>> Doug, is it possible the last updates have resulted in this happening?
>> Maybe there was no monitoring until then?
>>
>> 73 Jim KI7AY
>>
>>
>> On 05/17/2018 12:43 AM, "Doug Crompton via arm-allstar" wrote:
>>
>>> The Pi3B+ has a more advanced power and monitoring system. If you get a
>>> low
>>> voltage message it is probably worth looking into. The key here is under
>>> voltage and while this could be due to an under current power supply it
>>> does not mean that a "zillion" amp 5V power supply could not be under
>>> voltage. You need to check the voltage at the board with a good digital
>>> meter. Another important consideration is that the dynamic change in
>>> current of the board when heavily processing vs. idling can vary greatly.
>>> If the supply cannot handle these extremely fast current changes it could
>>> signal an under voltage condition. The wall wart you used to power your
>>> Pi2
>>> or Pi3B may not cut it for the 3B+ especially in turbo mode.
>>>
>>> I have had good success so far with wall warts BUT I consider myself
>>> lucky.
>>> I run 10+ Pi's with outlet strips full of wall warts. Ultimately this is
>>> probably not the way to go as besides the fact they can cause power
>>> problems they also emit a lot of RF noise. A better way would be to use
>>> the
>>> 12V to 5V 3A modules and run everything from a good 12V supply fusing the
>>> 12V input at each module. Here are a couple of examples. There are many to
>>> choose from on Ebay.
>>>
>>> https://www.ebay.com/p/Car-Buck-Converter-Step-down-Power-
>>> Supply-Voltage-Regulator-DC-12v-to-5v-3a-15w/19011441481
>>>
>>> https://www.ebay.com/itm/SUPERNIGHT-DC-DC-12V-24V-to-5V-3A-
>>> 15W-Converter-Step-Down-Power-Regulator-Module-/392044239513
>>>
>>>
>>> *73 Doug*
>>>
>>> *WA3DSP*
>>>
>>> *http://www.crompton.com/hamradio <http://www.crompton.com/hamradio>*
>>> _______________________________________________
>>>
>>> arm-allstar mailing list
>>> arm-allstar at hamvoip.org
>>> http://lists.hamvoip.org/cgi-bin/mailman/listinfo/arm-allstar
>>>
>>> Visit the BBB and RPi2/3 web page - http://hamvoip.org
>>>
>>>
>> --
>> 73 Jim
>> La ciruela de Panamá
>>
>> _______________________________________________
>>
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>>
>> Visit the BBB and RPi2/3 web page - http://hamvoip.org
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-- 
73 Jim
La ciruela de Panamá