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Octoprint on Pi - Undervoltage Detected  

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jweaver
(@jweaver)
Honorable Member
Octoprint on Pi - Undervoltage Detected

I installed Octoprint on a Pi when I built my Mk3, but rarely used it as a "FlashAir" card worked better.. After moving, I am too far from my Wifi to use the FlashAir, so have gone back to Octoprint

But it keeps reporting "Undervoltage detected". I ignore the error and everything is fine, but everytime I reload the GUI I get the same message.

After looking at the FAQ it seems to be a common problem and the solution is to insulate the +5v pin on the cable between the Printer and Pi.. But I also read that this doens't work on a Prusa.

I have changed the PSU to a good 2A one and still get the error, so I don't think its real.. And I have a feeling its down to the order in which the Printer and Pi are powered up.

Does anyone else have this? and does anyone know how to fix it?

Jon

 

Posted : 03/03/2022 12:00 pm
adesir
(@adesir)
Reputable Member
RE: Octoprint on Pi - Undervoltage Detected

I have changed the PSU to a good 2A one and still get the error, so I don't think its real.

What's a good 2A one?

What's the model of the Pi?

 

?

Mes modeles publics
Posted : 03/03/2022 12:58 pm
jweaver
(@jweaver)
Honorable Member
Topic starter answered:
RE: Octoprint on Pi - Undervoltage Detected

Its 2 I think from memory.

I did have a good Samsung 2A PSU before.. But now I changed to an Apple one and get the same issue.

 

Posted : 03/03/2022 1:09 pm
HermannSW
(@hermannsw)
Estimable Member
RE: Octoprint on Pi - Undervoltage Detected

You don't state which Pi you have. Older PIs up to Pi3B+ are fine with 2.5A power supplies, new Pi4B and Pi400 require 3A.

Best use the official power supplies (12.5W/15W):
https://www.raspberrypi.com/products/

I was told that phone chargers are not good for powering PIs, but the Samsung chargers I have work well.

In case you use non-official power supplies, your mileage may vary ...

Posted : 03/03/2022 2:09 pm
jweaver
(@jweaver)
Honorable Member
Topic starter answered:
RE: Octoprint on Pi - Undervoltage Detected

I said above.. A Pi2

It could be that Phone Chargers are not ideal but I assumed they would be more stable and able to deliver the stated current than a cheap Chinese PSU...

Posted : 03/03/2022 2:18 pm
jweaver
(@jweaver)
Honorable Member
Topic starter answered:
RE: Octoprint on Pi - Undervoltage Detected

I have dug out a whole bunch of PSUs and Chargers and some new cables.. And I can't get this to go away..

Even when its Idle, it still reports undervoltage.. Its almost like it detects it and then sets a state which cannot be cleared, even with a reboot.

If there really was too much current being drawn, the PSU would get hot.. its not even warm..

 

I don't know what option I have other than to just ignore it....

 

Posted : 03/03/2022 2:51 pm
towlerg
(@towlerg)
Noble Member
RE: Octoprint on Pi - Undervoltage Detected

It's undervoltage not undercurrent. Pi are quite particular re. input voltage which is why the genuine raspberry PSU is 5.1V

Posted : 03/03/2022 3:27 pm
jweaver
(@jweaver)
Honorable Member
Topic starter answered:
RE:

Surely its the same or atleast linked? PSUs will give a stable voltage until you draw too much current.. Thats when the voltage will drop

So if you take a 5v 1A PSU and draw upto 1A, it should still deliver a regulated 5V supply.. But as soon as you go over 1A, you will get heat and dropped voltage.

My assumption was that either the Pi is drawing more than 2A, or the PSUs are not stable and are not delivering 5v

But perhaps this isn't happening because of over current.. Perhaps the PSUs simply arn't delivering 5V at the end of the cable?

Posted : 03/03/2022 3:47 pm
HermannSW
(@hermannsw)
Estimable Member
RE: Octoprint on Pi - Undervoltage Detected

 

Posted by: @jweaver

But perhaps this isn't happening because of over current.. Perhaps the PSUs simply arn't delivering 5V at the end of the cable?

A multimeter will answer that for you.

Posted : 03/03/2022 4:44 pm
Diem
 Diem
(@diem)
Illustrious Member

Pi's reqire a small voltage overhead to power their USB lines and will complain if they don't get it.  This is why most USB supplies are *just* too low a voltage to maintain a Pi.

Many nominally 5.1v - 5.3v supplies also have very thin conductors and line resistance takes them too low.

It's best to use the correct official power supply for your Pi - even they are not all the same.

Cheerio,

Posted : 03/03/2022 5:49 pm
KevinK
(@kevink)
Trusted Member
RE: Octoprint on Pi - Undervoltage Detected

With all due respect for all the work in Octoprint, I find its fixation with Pi voltage excessive.  I have run everything from cheap chargers to official Pi power supplies on my Pis and still get warnings that in reality seem to be irrelevant.  I have never had any actual issue stemming from an undervoltage that I can tell.  I think the Pi is just extremely sensitive to even the shortest voltage excursion.  My "solution" is to disable the warnings in Octoprint.  It used to be that to do that you needed to go to the pi support menu in settings and open the "advanced" section and replace the command that checks for undervoltage with "echo throttled=0x00000" which essentially just tells Octoprint everything is fine.  I now see that there are check boxes that look like they will do the disabling.  Where I found this all the most annoying was when trying to update the Octoprint version.  It used to be (maybe still is) that Octoprint would actually refuse to do the update if the Pi had ever (from last boot) seen even a single undervoltage.  That is what drove me to change the check command since I had Pis with screens that would almost always see a momentary undervoltage during boot and then never later but Octoprint still wouldn't update them.

Posted : 03/03/2022 6:18 pm
bapski
(@bapski)
Estimable Member
RE: Octoprint on Pi - Undervoltage Detected

This solved my undervoltage issues:

https://www.amazon.com/gp/product/B07MC7B9X3/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

MY MODELS AT PRINTABLES
Posted : 03/03/2022 6:55 pm
towlerg
(@towlerg)
Noble Member
RE: Octoprint on Pi - Undervoltage Detected

With all due respect for all the work in Octoprint, I find its fixation with Pi voltage excessive.

Kinnda odd to say that Octoprint is obsessed with undervoltage, all it did was add a little lightning bolt to the UI. Really it's the Pi thats super sensitive. I can't speak to your assertion as I've never had a undervoltage flagged, always used genuine raspberry wall wart.

Where I found this all the most annoying was when trying to update the Octoprint version.  It used to be (maybe still is) that Octoprint would actually refuse to do the update if the Pi had ever (from last boot) seen even a single undervoltage. 

The reason why you should care it that undervoltage may throttle, corrupt or crash your Pi.

I really don't see that big deal, just use a suitable PSU. I note that bapski posts above that using a supply specified at 5.25V solves his problem.

 

Posted : 04/03/2022 12:43 pm
jweaver
(@jweaver)
Honorable Member
Topic starter answered:
RE: Octoprint on Pi - Undervoltage Detected

Whilst I source a new PSU, I have found a combination of cables/adaptors which is not giving me undervoltage alarms.

I am using a 10W Apple PSU, the type that you can remove the mains plug and put in a figure of 8 cable instead.. Bringing it closer to the printer and allowing me to use a shorter USB cable...

And now I am getting no errors.. So I am wondering of the voltage drop along the USB cable is the issue here, not the spec of the PSU?

Lets say you get a 0.2v drop on the cable.. If you start with a 5v PSU, this will mean feeding the pi with 4.8v.. But if you start with a higher voltage (i.e 5.25v) this means that even with the loss on the cable, you are still getting 5v at the Pi.

 

Posted : 04/03/2022 12:53 pm
towlerg
(@towlerg)
Noble Member
RE: Octoprint on Pi - Undervoltage Detected

 

Posted by: @jweaver

Surely its the same or atleast linked? PSUs will give a stable voltage until you draw too much current.. Thats when the voltage will drop

So if you take a 5v 1A PSU and draw upto 1A, it should still deliver a regulated 5V supply.. But as soon as you go over 1A, you will get heat and dropped voltage.

My assumption was that either the Pi is drawing more than 2A, or the PSUs are not stable and are not delivering 5v

But perhaps this isn't happening because of over current.. Perhaps the PSUs simply arn't delivering 5V at the end of the cable?

The point is that Pi want more than 5V, eg. a genuine raspberry 5.1V wall wart

Posted : 04/03/2022 12:56 pm
KevinK
(@kevink)
Trusted Member
RE: Octoprint on Pi - Undervoltage Detected

The reason why you should care it that undervoltage may throttle, corrupt or crash your Pi.

I really don't see that big deal, just use a suitable PSU. I note that bapski posts above that using a supply specified at 5.25V solves his problem.

I'm glad that worked for you.  What I, unfortunately, have had is Pi systems with Adafruit touchscreens that WITH THE OFFICIAL PI PSU still cannot get through boot without seeing a power drop.  That drop never impacts them in any lasting way.  However, Octoprint will refuse to update if it sees that a power drop has ever happened during the life of a Pi power cycle and getting around that requires (or at least did a while back) removing Octoprint's ability to see that a throttle ever happened.  I don't suggest anyone else routinely do that if they are nervous about it but it took me a bunch of poking to find a workaround so I thought I'd share it.  I run quite a few Pi's of various models in various configurations so I am not inexperienced with them (or with hardware and software generally as I spent 35 years with Intel much of which running parts of their systems research labs).  I have no issue with Octoprint's informative lightning bolt but all such checks should have an easy (even if hidden in a special menu) override.  I had an exchange on this in the Octoprint forum a long while back but just gave up and found the workaround (which quite honestly is overkill since it does more than just handle update prevention).

Posted : 04/03/2022 6:44 pm
Just Brad
(@just-brad)
Eminent Member
RE:

I had been swapping a few raspberry PI power adapters and found out that if the message file contains an old under-voltage OctoPrint would issue a warning based on scanning the a log file.

If you continue to get a warning about power while logged into the Raspberry PI, then the issue is not in the message file but with the hardware itself.

Below is a simple script that will print out some nice status of the Raspberry PI.

The problem with the script is that it reports what the current status; so it is more than possible to miss temp or other issues.

The best power supply for the raspberry PI is the ones that are from Raspberry PI and meet the power requirements for the specific version of the PI.

pi@MKIV:~ $ more check_power#!/usr/bin/env bash

pi@MKIV:~ $ more check_power
#!/usr/bin/env bash

SCRIPT=$(basename "$0")

# fetch status
STATUS=$(vcgencmd get_throttled | cut -d "=" -f 2)

# decode -  https://www.raspberrypi.com/documentation/computers/os.html#get_throt 
tled
echo "vcgencmd get_throttled ($STATUS)"
IFS=","
for BITMAP in \
   00,"currently under-voltage" \
   01,"ARM frequency currently capped" \
   02,"currently throttled" \
   03,"soft temperature limit reached" \
   16,"under-voltage has occurred since last reboot" \
   17,"ARM frequency capping has occurred since last reboot" \
   18,"throttling has occurred since last reboot" \
   19,"soft temperature reached since last reboot"
do set -- $BITMAP
   if [ $(($STATUS & 1 << $1)) -ne 0 ] ; then echo "  $2" ; fi
done

echo "vcgencmd measure_volts:"
for S in core sdram_c sdram_i sdram_p ; do printf '%9s %s\n' "$S" "$(vcgencmd me
asure_volts $S)" ; done

echo "Temperature: $(vcgencmd measure_temp)"

 

output

vcgencmd get_throttled (0x0)
vcgencmd measure_volts:
core volt=0.8800V
sdram_c volt=1.1000V
sdram_i volt=1.1000V
sdram_p volt=1.1000V
Temperature: temp=43.3'C

 

This post was modified 2 months ago 2 times by Just Brad
Posted : 25/12/2023 5:54 pm
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