qwertinsky
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Re: Under-voltage warnings

Sun Apr 12, 2015 8:34 am

rpdom wrote:
qwertinsky wrote:Obviously this problem is due to voltage drop in the USB cables . I am sure you would be lucky to find anything larger than 28 gauge wire in a micro USB cable.
It seems you buy cheap micro USB cables.

Anything up to 20AWG is available if you look for it.
You just made my point, I should not have to look for it.

If they put a "real" power connector on it to begin with, this would never have been an issue.

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DougieLawson
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Re: Under-voltage warnings

Sun Apr 12, 2015 8:41 am

qwertinsky wrote:
If they put a "real" power connector on it to begin with, this would never have been an issue.
If they did that then we'd have 1,000,000 dead Raspberry Pis from folks using the wrong polarity and/or the wrong voltage. Barrel connectors are a monster PITA.
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mikerr
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Re: Under-voltage warnings

Sun Apr 12, 2015 8:42 am

qwertinsky wrote: If they put a "real" power connector on it to begin with, this would never have been an issue.
remind me again what the standard power connector for 5v looks like?

looking around here my barrel connectors tend to be laptop PSUs at 19v - don't fancy pi's chances against that!

I can however pickup any random microusb and expect it to work (or at least not blow up )
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rpdom
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Re: Under-voltage warnings

Sun Apr 12, 2015 8:45 am

[quote="qwertinsky"If they put a "real" power connector on it to begin with, this would never have been an issue.[/quote]
A "real" :roll: power connector with no standards whatsoever? That'll be great. I'll just plug my 20VAC wall wart with a barrel connector into your Pi, shall I?
]You just made my point, I should not have to look for it.
I got your point. You can't be bothered to look for it and are quite happy to use cheap knock-offs :lol:

qwertinsky
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Re: Under-voltage warnings

Sun Apr 12, 2015 5:41 pm

DougieLawson wrote:
qwertinsky wrote:
If they put a "real" power connector on it to begin with, this would never have been an issue.
If they did that then we'd have 1,000,000 dead Raspberry Pis from folks using the wrong polarity and/or the wrong voltage. Barrel connectors are a monster PITA.
A diode that cost .001 cent and a 5v regulator .02 cent at 1,000,000 quantities would prevent that.

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mahjongg
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Re: Under-voltage warnings

Sun Apr 12, 2015 6:48 pm

qwertinsky wrote:
DougieLawson wrote:
qwertinsky wrote:
If they put a "real" power connector on it to begin with, this would never have been an issue.
If they did that then we'd have 1,000,000 dead Raspberry Pis from folks using the wrong polarity and/or the wrong voltage. Barrel connectors are a monster PITA.
A diode that cost .001 cent and a 5v regulator .02 cent at 1,000,000 quantities would prevent that.
No it would not! Considering a user could easily plug in a 17V supply, your .02 cent 5V regulator (i'm assuming you mean a bog standard 7805 derivate) would either need a heatsink the size of a PI, or it would overheat immediately. Even an optimal 8V for a cheap 5V passive regulator would need a large and expensive heatsink. and you price estimates are ridiculous, and leave out a lot you are not mentioning, like decoupling caps, 1500uF buffer caps etc. also an 7805 cannot supply 2A, and low drop replacements are more expensive, only totally phased out china junk is priced at anything nearly as low as you claim.

this is a gone and past station in a discussion which was held 3 years ago, and concluded in that the way the RPF did it was the way to go. Barrel connectors, and passive 5V regulators were the technology found in old equipment two decades ago, they are passé now, and i'm glad we got rid of them.

they would also have caused more grief than this alternative solution.

mikerr
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Re: Under-voltage warnings

Tue Apr 14, 2015 8:41 am

I wrote this quick python script to view the power led status over ssh,
may be useful as a template for others:

Code: Select all

 #!/usr/bin/python
    import RPi.GPIO as GPIO , time

    redLED=35
    GPIO.setmode(GPIO.BCM)
    GPIO.setup(redLED, GPIO.IN)

    powerlow=0
    while True:
            if(GPIO.input(redLED)==0):
                    print "POWER dipped below 4.63v"
                    powerlow += 1
            else:
                    powerlow =0
            if (powerlow  > 3):
                     print "Low power for " + str(powerlow) + " seconds"
            time.sleep(1)
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electronicsguy
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Re: Under-voltage warnings

Fri Apr 17, 2015 12:50 am

mikerr wrote:I wrote this quick python script to view the power led status over ssh,
may be useful as a template for others:
Using Mike's code, I made a script which uses ANSI control codes to constantly display the LED status in the top right corner. Could someone test it out with the undervoltage message? I don't have the means to do that here.

download link: http://bit.ly/1Dp9gkH

run it as: sudo python test.py &

Code: Select all

#!/usr/bin/python

import RPi.GPIO as GPIO , time
from subprocess import call
import shlex
import sys

import signal

def handler(signum, frame):
#	call(shlex.split("echo -ne '\e[u''\e[0m'"))
	sys.exit()

signal.signal(signal.SIGINT, handler)

redLED=35
GPIO.setmode(GPIO.BCM)
GPIO.setup(redLED, GPIO.IN)

powerlow=0
#call(shlex.split("echo -ne '\e[s'"))
while True:
	if(GPIO.input(redLED)==0):
		call(shlex.split("echo -ne '\e[s''\e[1;56H''\e[1;31m'POWER dipped below 4.63v'\e[u''\e[0m'"))
		powerlow += 1
	else:
		powerlow = 0
		call(shlex.split("echo -ne '\e[s''\e[1;78H''\e[1;31m'ON'\e[u''\e[0m'"))

	if (powerlow  > 3):
		break
    
	time.sleep(1)

#call(shlex.split("echo -ne '\e[u''\e[0m'"))
print "Low power for " + str(powerlow) + " seconds"

blog: https://electronicsguy.wordpress.com
github: https://github.com/electronicsguy

mikerr
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Re: Under-voltage warnings

Tue Apr 21, 2015 8:39 pm

That's good - I can confirm that works ok for seeing the LED in the top right of the SSH console.

For testing I have a thin 2M long microUSB cable that makes the voltage drop/LED go out when the CPU is hammered
( cat /dev/urandom >/dev/null)
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electronicsguy
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Re: Under-voltage warnings

Tue Apr 21, 2015 8:51 pm

cool. Does any 2m USB cable work, or a specific, low-cost one?
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FTrevorGowen
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Re: Under-voltage warnings

Wed Apr 22, 2015 8:27 am

electronicsguy wrote:cool. Does any 2m USB cable work, or a specific, low-cost one?
It doesn't have to be 2m long to be "bad enough"!:
http://www.cpmspectrepi.webspace.virgin ... esChk.html
Trev.
Still running Raspbian Jessie on some older Pi's (an A, B1, B2, B+, P2B, 3xP0, P0W) but Stretch on my 2xP3A+, P3B+, P3B, B+, A+ and a B2. See: https://www.cpmspectrepi.uk/raspberry_pi/raspiidx.htm

Fght
Posts: 319
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Re: Under-voltage warnings

Sat Apr 25, 2015 4:47 pm

hi

i'm still having issues with the rainbow square indicating i've under voltage.
it is even after i bought another "strong" power supply.

i live in israel and if you are telling me i better off ordering from ebay - then it means i'm not sure how to look for the right socket like in my country.
if you can assist me with finding a good listing on ebay.
ps
i also tried different cables.

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mahjongg
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Re: Under-voltage warnings

Sat Apr 25, 2015 5:14 pm

You may have used different cables but that just proves how ubiquitous really bad charger cables are.

If you have a good finely regulated power supply that can proved 5.00V without dipping significantly when current goes from 500mA to 1500mA, then the only reason that 5.00 V doesn't make it to the PI intact is because the cable has so much resistance that by the time the power makes it to the PI less than 4.65V remains, causing the low power indicator.

If you can't find any cables that work, you may try to cut off the cable close to the microUSB, and solder a regular cable with real copper wires to the ends of the cable from the microUSB, if the tinsel foil, or perhaps strands of aluminum interwoven with nylon cord let you solder real wires to them.

make sure you don't reverse the polarity, or you will blow up the PI! Any metal connector shells of the PI should be connected to GND, and can be used to measure which wire is connected to GND with a multimeter.

raspdealer
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Re: Under-voltage warnings

Tue Jun 09, 2015 8:33 pm

Hi,

For 1 week now, I got (sometimes) a warning like that.
It's a red orange gradient, so it's the red one or the rainbow one ? :)

Nothing changed in my setup : rpi1 + usb power + usb hub + power supplier. So why this happend now ? and not everytime ?

Thanks for help,

R.

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mahjongg
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Re: Under-voltage warnings

Tue Jun 09, 2015 9:37 pm

Sounds like you get the overtemperature warning, which resembles the undervoltage warning but is red, instead of "rainbow".

raspdealer
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Re: Under-voltage warnings

Wed Jun 10, 2015 6:39 am

Okkkkk thank you. I will try to add a touch of fresh air :p

Fght
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Re: Under-voltage warnings

Sun Jun 14, 2015 2:19 am

i got it solved
someone told me to buy a specific power supplier from ebay cheaply and it really worked. i don't see the thing blinking anymore.

mannkeithc
Posts: 3
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Re: Under-voltage warnings

Thu Jul 30, 2015 4:24 pm

I have a raspberry rpi 2 that displays the red square "over temperature" warning when the device is initially powered up. The small red square appears top right hand side adjacent the larger multi coloured square that fills the centre of the screen before the rpi starts to boot. The red square disappears after 1 second, the multi-coloured square then disappears, and then the scrolling text appears as the rpi boots.

I am surprised the red square "over temperature" warning appears at start-up, since the rpi is cold. I have checked the rpi's running temperature using the "vcgencmd measure_temp" and it sits around 40C and hence appears OK. I am not over-clocking the rpi and running with a defaults configured after using NOOBS to install Raspbian OS. Voltage levels are good and red power LED remains stable while the rpi is running.

I have a second rpi 2 that does not display the red square "over temperature" warning on start-up / power up.

Is my first rpi 2 running with some test mode configured that forces it to display the red square "over temperature" warning at start-up?

Regards,
Keith

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davidcoton
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Re: Under-voltage warnings

Thu Jul 30, 2015 9:27 pm

Are you sure it is a red temperature warning, not a rainbow undervoltage warning? I can't see how you would get a valid over temperature at startup under normal environmental conditions. OTOH, startup conditions often create transient undervoltage. Try swapping the power supplies between your Pis, since it is usually a function of the PSU rather than the Pi.
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dom
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Re: Under-voltage warnings

Fri Jul 31, 2015 11:11 am

mannkeithc wrote:Ig with some test mode configured that forces it to display the red square "over temperature" warning at start-up?
What does "vcgencmd version" report?
There was a bug in old versions of the firmware where the warning could appear spuriously on boot.
"sudo apt-get update && sudo apt-get upgrade" should fix that.

mannkeithc
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Re: Under-voltage warnings

Fri Jul 31, 2015 7:51 pm

The small square is predominantly red with an orange tint on the RHS, so it is not pure red, and as you say could be be "under voltage" warning arising due to transient voltage levels when the device is first powered on. The small square does not include any blues or yellows - i.e. did not resemble a rainbow like the big square, hence I first thought it was a "temperature" warning.

I have also tried different PSUs and no change. My second Pi 2 using the same PSUs does not display any small warning square at start-up. I have also tried disabling and removing the camera board fitted, and no change.

vcgencmd version reports:
July 24 2015 14:44:13
Copyright (c) 2012 Broadcom
version 0f482c5017ad4526a6beb77fe39c93189c664fd4 (clean) (release)

uname -a reports:
Linux [hostname] 4.0.9-v7+ #807 SMP PREEMPT Fri Jul 24 15:21:02 BST 2015 arm7l GNU /Linux

I do regular update & upgrade the software. I have also performed a firmware update. Is 4.0.9-v7 the latest firmware version?

Thank you.
Keith

dom
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Re: Under-voltage warnings

Sun Aug 02, 2015 6:42 pm

mannkeithc wrote:The small square is predominantly red with an orange tint on the RHS, so it is not pure red, and as you say could be be "under voltage" warning arising due to transient voltage levels when the device is first powered on. The small square does not include any blues or yellows - i.e. did not resemble a rainbow like the big square, hence I first thought it was a "temperature" warning.
Sounds like the over-temperature warning. If your firmware/kernel is from a week ago, then that will have the fix.
Are you using NOOBS? Be aware with NOOBS that there is a NOOBS boot partition and a raspbian boot partition, each with their own firmware/kernel.
It is possible the NOOBS partition has older firmware.

mannkeithc
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Re: Under-voltage warnings

Mon Aug 03, 2015 8:29 am

I have solved the issue, though I don't exactly understand the precise root cause. I found the problem followed the Raspbian OS image and not the RPi 2 device as previously thought.

I was using a newer NOOBS generated Raspbian OS build for my second RPi 2 that didn't display the warning square on start-up. Both Raspbian OS builds were running with the latest firmware and software updates, but I noticed there were subtle differences in the boot-up sequences, including the default NOOBs settings used for RPi 2 clocking. When I swapped the microSD cards in the the two RPIs 2, the issue followed the card.

The card with the issue was a NOOBS generated Raspbian OS build originally created on a RPi B+. I then purchased my first RPi 2 and used the card from the B+ after I had first ensured it was running with latest firmware compatible with a RPi 2. At the time I thought the additional small square was a difference of the RPi 2 quad core Vs B+ single core. It wasn't until I acquired my second RPi 2 running a newly created build on a second microSD card, I noticed the difference and searched the web for more information.

Yesterday I built a new Raspbian OS build on third microSD card for my first RPi 2. Everything went as expected, and this time no small warning square on start-up. So it turns out not to be a real issue :oops:

Thank you to everyone for your help and advice.

Regards,
Keith

aworthey
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Re: Under-voltage warnings

Thu Sep 03, 2015 9:37 pm

@Fght Where did you get your power cord on eBay?

bvoid
Posts: 1
Joined: Sun Sep 13, 2015 8:05 pm

Re: Under-voltage warnings

Sun Sep 13, 2015 8:28 pm

On my B+, the powerled turns off a few seconds after booting and never shows up again, but the rainbow square is not displayed! I do see the Raspberry symbol on my monitor :)
I soldered wires straight to the board, starting from a molex-connector that's connected to a 850W psu (Antec High Current gamer).
With crappy usb-cables or power supplies, I dó see the rainbow square, so it's definitely possible that it shows.

I'm running OpenWrt Chaos Calmer RC3, with the latest ROOter scripts and a wifi usb stick and a 3g stick. Plugging out these devices does not help.


Any ideas, as this behaviour is nowhere to be found on google.. ?

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