Under-voltage warnings

[dom]

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.

The led is software controllable, and the custom kernel you are using probably isn't configuring it correctly.
Try a raspbian image which I suspect will work.

At a guess I'd say CONFIG_LEDS_TRIGGER_INPUT=y is missing.

[fredfs]

Can I check the voltage status from the command line?

Would like to check my headless pi

[BrutynNick]

Hey,

I watched a movie yesterday on the raspberry pi 2, and then I saw a colored square in the top right corner.
I saw this for 10 sec, then it disappeared, and appeared again few times, 5, 10 mins later.
I sometimes saw a big colored square when it booted in the past ( 2-3 times), but then it worked after rebooting...

I have my raspberry pi 2 since 15/03/2015, and this is the first time I saw this.
I bought the Raspberry Pi 2 Media Centre Kit from http://thepihut.com/. This contained ThePiHut 5V 2A Power Supply EU.
I read here that it is a undervoltage problem? How come I can get this problem with the included power supply?
I don't use a usb power supply or something like that. Just this:
-Raspberry Pi 2
-Network cable
-power supply (included in the kit, connected in the power socket)
-usb 2.0 stick 16 GB
-SD card (included in the kit).
-openelec kodi

I don't install plugin's on the raspberry pi 2, and not running much (I think).
I just watch movies.

Thanks in advance.

[davidcoton]

The big square on booting is normal, not a warning of anything (except possibly Pi addiction ahead )
The small square while running is either a low voltage warning (multicoloured/rainbow) or an over temp warning (red/orange I think, and unlikely).
Are you overclocking the Pi? This can lead the overheating.
If there are no other peripherals, then the 2A supply should be plenty, so the PSU or its cable are suspect -- check with a voltmeter, and complain (politely) to the supplier.

[BrutynNick]

Hey,

Thanks for the reply.
It's the low voltage warning (multicoloured/rainbow) that I saw.
I don't overclock it, only normal use.
Today I didn't get the warning, maybe just a temporary power shortage...

[boyoh]

I'm enjoying this post very much, But I'm still non the wiser. He must ware a belt and bracers to hold his trousers up

and suspenders on his socks He must sleep with the light on to let him know when it as gone out.

[paulv]

I really don't want to stir this pot, but it seems to me that there is too much guessing going on about the under-voltage issue, without enough concrete data to help find a root cause or fix.

There is a post that I specifically taylored and created with this issue in mind. Have a look at this and see if it can do the job for you. You have to modify the code a little to do some data logging over time to find the culprit(s) in your particular environment, but that should not be so hard :
viewtopic.php?f=37&t=123962

I hope this helps,
Paulv

[davidcoton]

I've added some comments to that other thread, it may be fun but the approach is complex and has limitations.The rainbow square is already telling you there is a problem with the 5V rail. If the problem is bad enough and persistent enough to need investigation, a multimeter and some common sense will give you the answers -- which in general (though not in every specific case) are well understood.

[Hitechcomputergeek]

Just curious, what would happen if both an under-voltage warning and a temperature warning were to be generated at the same time? What would be displayed on the screen?

[dom]

Just curious, what would happen if both an under-voltage warning and a temperature warning were to be generated at the same time? What would be displayed on the screen?

The under-voltage signal is displayed.

[Rob73]

I have a RaspberryPi 2B with a fresh NOOBS_v1_7_0, where the small-rainbow-square under-voltage warning shown on my official-7"-raspberrypi-touchscreen fine. HOWEVER, as soon as I do a "sudo apt-get update & upgrade" (and reboot), the small-rainbow-square shows briefly whilst NOOBS is initially starting, but then stops showing when the main Rasbian-GUI starts loading. (Note the Pi's power-led is off indicating low-power, and I know I am feeding it low-power.)

I also have a RaspberryPi 3 with a fresh NOOBS_v1_8_0 (not updated), where again the small-rainbow-square shows briefly whilst NOOBS is initially starting, but then stops showing when the main Rasbian-GUI starts loading.

I also have a RaspberryPi 3 with a fresh "2016-02-26-raspbian-jessie" (ie.no NOOBS, & not updated), which NEVER shows the small-rainbow-square even though the power-led is off indicating under-voltage.

Running "sudo apt-get update & upgrade" (as at 9Mar16) on either RaspberryPi's does not make any difference. I therefore suspect that this "low-power-small-rainbow-square" warning on the screen (which I find very usefull!), does NOT work in "NOOBS_v1_8_0" or "2016-02-26-raspbian-jessie" (with or without updates as at 9Mar16). (I also suspect the small-red-square over-temp warning wont work either).

If there is a fix for this, I would appreciate it!

Update: "sudo apt-get update & upgrade" (as at 14Mar16) has now fixed this, and the "small-rainbow-square under-voltage warning" now shows up correctly on both my RasPi-2B and RasPi-3. Thanks!

[SandPox]

Is there any way to get "Under-voltage warnings" from userspace?

[dom]

If there is a fix for this, I would appreciate it!

There is - it is on rpi-update firmware and will be in apt-get firmware imminently (next few days).

[joanlo]

Dear
How can I read the under voltage status or level warning?. I want to read this to shutdown the RP when it apperars.
Best regards.

[Synoia]

I use a very short USB cable (about 1 ft) and the best power supply I can find.

2.1 A @ 5 V over a thin cable = voltage loss.

[dom]

Dear
How can I read the under voltage status or level warning?. I want to read this to shutdown the RP when it apperars.
Best regards.

Code: Select all

vcgencmd get_throttled

If it is zero all is good. If it is non-zero then throttling has occurred, which may be due to under-voltage. See here for interpretation.

[mahjongg]

Just curious, what would happen if both an under-voltage warning and a temperature warning were to be generated at the same time? What would be displayed on the screen?

Its my understanding that both would be displayed next to each other.

[dom]

Just curious, what would happen if both an under-voltage warning and a temperature warning were to be generated at the same time? What would be displayed on the screen?

Its my understanding that both would be displayed next to each other.

No, the low voltage symbol takes precedence.

[cwacha]

How can I change the symbol? In which file and in what format is the image stored. I assume somewhere in the kernel?

Thanks
Clemens

[dom]

How can I change the symbol? In which file and in what format is the image stored. I assume somewhere in the kernel?

You can't. It's not a bitmap - just 4 coloured pixels scaled up.
There is a plan to update the symbols. See: https://github.com/raspberrypi/firmware/issues/367

[demi733]

Hello all! I would like to know if anyone knows an "easy" way to remove the temperature warning but retain the under voltage warning? The reason I am doing this being that I am using the temp_limit to force my cpu to stay throttled. I am forcing this behaviour using this method for two reasons; firstly, Iam in an area that is very warm, so it makes sense to keep the cpu constantly throttled, and secondly, I am running off of a switching 12v to 5v dc inverter and altho it is rated at 3amps (15 watts) I get hickups when doing processor intensively actions. Any help on this would be greatly appreciated. Thank you. (side note: I've put together a hideous script that polls voltage, etc, however, using this method does not necessarily tell me how much of the voltage that is being drawn is "under" the desired threshhold. There may be other ways to achieve my desired results if I cannot take the easy way of keeping the lightning bolt icon while still removing the temp icon)

[dom]

Why not just switch to the powersave governor? That will run throttled all the time without invoking the temperature limit.

Code: Select all

echo powersave | sudo tee /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor

should do it.

[dom]

There is a plan to update the symbols. See: https://github.com/raspberrypi/firmware/issues/367

For anyone who hasn't seen, this is now implemented in rpi-update firmware (and very soon in apt-get firmware). See first post.

[demi733]

Why not just switch to the powersave governor? That will run throttled all the time without invoking the temperature limit.

Code: Select all

echo powersave | sudo tee /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor

should do it.

My understanding on using cpufreq from reading many different posts was that this was not the desired method. I did try simply throttling the cpus down entirely with config.txt min and max values but when polling the current freq my pi was ignoring it. Either that, or I typoed a character. Again, I like the temp throttling concept as a means to acheieve a force in cpu freq scaling as one factor I have noticed is a spike in temp during high processor loads which results in the low voltage warning. This is currently not a huge issue as of yet since I am powering my peripherals from a separate 20Ah battery with 2.1v and 1v dc outputs but when I first purchased this particular pi, I was able to easily power my usb devices and monitor over the pi's usb without issue. I am also no longer running in an environment that is easily 30 degrees cooler F than I am now and I was also using a 2A power supply that came with my western digital pi harddrive kit. Irony there being that that PSU was only 2A and my switching inverter should be providing 3A. Anyhow, I digress. Simple answer to your query is that I am a creature of habit and cpufreq doesn't appear to be producing the results I wish to achieve as quickly. temp_limit has been working brilliantly and it'd be brilliant if I could still monitor the under voltage watermark while omitting the temp. Not critical as of yet, again. But I would like to start plugging my usb stuff back into the pi and not into separate sources of power. I can buy some gpio pins and get the voltage warnings overe that still, if I am not mistaken. Only issue is I am cheap and fairly poor and it takes an eternity to ship to my current location. While, I am here, perhaps I should make a separate post, but I'll give it a go. Any idea why one of my rpi3 B's no longer powers the USB ports? I have yet to ssh and check dmesg etc, simply cause I fried my router. Bwah bwah. I had a bunch of pi's running in a little cluster before I moved and they worked seemlessly. I arrive and I had problems with them all. All of which I managed to fix aside form this particular one. It boots perfectly fine. No apparent messages. I do believe the ethernet still works but I cannot honestly remember. I'll take a look later on. Again, thank you for your time and information. I appreciate it.

[demi733]

I will try your powersave method as well, btw, and see how that goes.