Under-voltage warnings

[B.Goode]

Could you please let me for how many seconds or milliseconds the indication will be there on the screen after the under voltage event has occurred.

From the thread you are participating in -

viewtopic.php?f=29&t=82373#p582186

[hippy]

A related question - Alongside the "is under-voltage" flag there is the "has been under-voltage" flag. Is it possible to clear the latter from the command line or programmatically without rebooting ?

I may have missed it but I couldn't see a 'vcgencmd reset_throttled' or similar.

That would be nice to have as there is much lower overhead in leisurely checking the "has been under-voltage" and clear that than have to continually poll the "is under-voltage"flag.

[dom]

I may have missed it but I couldn't see a 'vcgencmd reset_throttled' or similar.

See: https://github.com/raspberrypi/linux/is ... -364197053
(but be aware of the caveat)

[TimG]

See: https://github.com/raspberrypi/linux/is ... -364197053
(but be aware of the caveat)

I don't seem to be able to get this to work. With up-to-date Raspbian, kernel 4.14.34-v7+:

Code: Select all

tim@srv2:~ $ vcgencmd get_throttled
throttled=0x50000
tim@srv2:~ $ vcgencmd get_throttled 0x05
throttled=0x0
tim@srv2:~ $ vcgencmd get_throttled 0x05
throttled=0x0
tim@srv2:~ $ vcgencmd get_throttled
throttled=0x50000
tim@srv2:~ $ vcgencmd get_throttled 0x50000
throttled=0x0
tim@srv2:~ $ vcgencmd get_throttled
throttled=0x50000

sudo doesn't make any difference.

[dom]

I don't seem to be able to get this to work. With up-to-date Raspbian, kernel 4.14.34-v7+:

Always read with "vcgencmd get_throttled 5"
If it returns zero then no under-voltage / over-temp has occurred since it was last read.
It it returns non-zero then those bits have occurred since last read.

But if you are using a recent kernel which also uses this interface you will probably find it consumes some of these events.

[TimG]

Always read with "vcgencmd get_throttled 5"
If it returns zero then no under-voltage / over-temp has occurred since it was last read.
It it returns non-zero then those bits have occurred since last read.

But if you are using a recent kernel which also uses this interface you will probably find it consumes some of these events.

Ah-ha! So if I want to check for fresh under-voltage events I'm better off reading dmesg?

[dom]

Ah-ha! So if I want to check for fresh under-voltage events I'm better off reading dmesg?

Yes, that would probably be best.

[TimG]

Thanks!

[HermannSW]

I am confused, vcgencmd does not show undervoltage:

Code: Select all

pi@raspberrypi3BplusX:~ $ vcgencmd get_throttled 5
throttled=0x0
pi@raspberrypi3BplusX:~ $ 

But XWindows clearly shows undervoltage(?):



I have not seen this with official power supply back home in Germany with Waveshare 7" LCD. But I used that display not much there. Now on vacation in Denmark I see it frequently. I thought we have shared power grid in Europe, or are there differences in countries that can explain undervoltage in DK and no untervoltage in D? (same setup)

Or is this a temperature warning?

[DirkS]

Or is this a temperature warning?

yes, see https://www.raspberrypi.org/documentati ... g-icons.md

[HermannSW]

Thank you!

So what I saw frequently was the 80-85 degree warning symbol.
Reason was that I used PI 3B+ lying flat on desk or Trip Trap.
Now knowing about over temperature I tried PI 3B+ "standing".
And it worked, temperature did rise until above 70 degree C, but never reached 71:

[PlasticDog]

I don't seem to be able to get this to work. With up-to-date Raspbian, kernel 4.14.34-v7+:

Always read with "vcgencmd get_throttled 5"
If it returns zero then no under-voltage / over-temp has occurred since it was last read.
It it returns non-zero then those bits have occurred since last read.

But if you are using a recent kernel which also uses this interface you will probably find it consumes some of these events.

So then, is vcgencmd get_throttled not really usable for detecting when to perform an automatic shutdown. Specifically, I'm using a pi zero w, and I was hanging my hat on that possibility for unattended battery power usage.

[HermannSW]

Back in Denmark for vacation, in same house, with same Trip Trap as base for 7" lcd display, with Pi 3A+ in case without cover this this year:



All was fine until I remembered that I had to push the Pi a bit.
I did execute 10 times this command in background:

Code: Select all

$ wile true; echo > /dev/null; done &

This did raise overall CPU utilization to 74% over all 4 cores, and after some time temperature measured by "vcgencmd measure_temp" above 80°. Finally the over temparature symbol appeared again.

I removed the case, and made Pi 3A+ stand vertical as I did last year with Pi 3B+. As last year temperature did not go above 73° this time. So for low CPU utilization case is fine, but for high CPU utilization (at least with DPMI display) case becomes unusable because over temparature warning symbol keeps showing up all the time.

[ProDigit]

Hi,
Is it possible to use a higher arm frequency when the lightning icon is displayed?
When plugging it into a 2A charger, the max CPU speed is throttled at 600MHZ.
I was hoping it could be upped to 900 or 1,2Ghz, just like when it is triggered by overheating.

Thanks!

*Edit: Nevermind! avoid_warnings=2 allowed the Pi to operate like normal (including overclocked), despite only feeding it (a stable) 2A.

[PeterO]

Hi,
Is it possible to use a higher arm frequency when the lightning icon is displayed?

So you want to make the PI draw even MORE current when it is already showing low voltage warnings because the PSU is struggling to maintain the voltage high enoughit ?

PeterO

[ProDigit]

Hi,
Is it possible to use a higher arm frequency when the lightning icon is displayed?

So you want to make the PI draw even MORE current when it is already showing low voltage warnings because the PSU is struggling to maintain the voltage high enoughit ?

PeterO

The pi 3B+ is measured at around 1A 5W if I'm not mistaken.
My PSU is a dual USB unit, providing 3.2A split over the display (0.5A) and the Pi 3B+. The pi should be provided with 2A, and an additional 0.4A reserve. In theory, as each port is Max rated 2,4A. I shouldn't even be able to see the lightning icon.

The fact that my pi (with LCD hat) arm freq runs fine at 1510Mhz, GPU at 525, Ram at 525 without errors, shows that there's some fine tuning needed in the way the 3B+ handles power, and that there's no need for 600Mhz throttling.

Perhaps when running the pi at stock frequencies, I won't get the lightning icon, as it sometimes appears and disappears. I guess I'm running it right on the threshold.

At best, I'd say arm freq 1,2Ghz throttling at 2A, and 600Mhz when voltage drops further (1,5A? I believe I've booted the pi with a 1500mA charger before.
Perhaps disable overclocking at below 2A, as most USB adapters on the market are 2A, 10W, and the pi runs fine even overclocked at those power figures.

[RaTTuS]

if it is displaying undervoltage then it is not getting 5V

[LTolledo]

"....complaining about the RPi board 'complaining due to lack of power'......."

.....one proposed solution is to "silence the complaint of the board"..... yeah right...

....until the board has endured enough..... until the last "bit of life".....

...and then more complaints come in.... about the RPi board "not functioning", "non-responsive",......"dead"........

...due to a "simple" cause....neglect on the part of the RPi board user/owner......

[Imperf3kt]

Hi,
Is it possible to use a higher arm frequency when the lightning icon is displayed?

So you want to make the PI draw even MORE current when it is already showing low voltage warnings because the PSU is struggling to maintain the voltage high enoughit ?

PeterO

The pi 3B+ is measured at around 1A 5W if I'm not mistaken.
My PSU is a dual USB unit, providing 3.2A split over the display (0.5A) and the Pi 3B+. The pi should be provided with 2A, and an additional 0.4A reserve. In theory, as each port is Max rated 2,4A. I shouldn't even be able to see the lightning icon.

The fact that my pi (with LCD hat) arm freq runs fine at 1510Mhz, GPU at 525, Ram at 525 without errors, shows that there's some fine tuning needed in the way the 3B+ handles power, and that there's no need for 600Mhz throttling.

Perhaps when running the pi at stock frequencies, I won't get the lightning icon, as it sometimes appears and disappears. I guess I'm running it right on the threshold.

At best, I'd say arm freq 1,2Ghz throttling at 2A, and 600Mhz when voltage drops further (1,5A? I believe I've booted the pi with a 1500mA charger before.
Perhaps disable overclocking at below 2A, as most USB adapters on the market are 2A, 10W, and the pi runs fine even overclocked at those power figures.

You are confusing voltage and current (amperes)
Don't blindly trust the label.
The charger says it supplies 2A doesn't mean it supplies 5v while you're drawing 2A. As you draw more current, the voltage can drop and this is why you are seeing an 'undervolt' warning.

Also, setting the clock to 1510MHz does not mean your Pi is running at 1510MHz.

[jamesh]

Note that if the warning is being reported, you may be more susceptible to SD card corruption, random RAM corruption, USB communication failures etc. All of these may be happening right now but you may not be noticing them. Until one of them hits something critical. Then you will.

[PeterO]

At best, I'd say arm freq 1,2Ghz throttling at 2A, and 600Mhz when voltage drops further (1,5A? I believe I've booted the pi with a 1500mA charger before.
Perhaps disable overclocking at below 2A, as most USB adapters on the market are 2A, 10W, and the pi runs fine even overclocked at those power figures.

You don't know what you are talking about
Please go and find some tutorials on basic electricity that explain the relationships between Voltage,Current,Resistance and Power.

At the moment you are just making yourself look foolish by posting stuff that makes no sense and shows you don't understand the basics.

PeterO

[ProDigit]

You are confusing voltage and current (amperes)
Don't blindly trust the label.
The charger says it supplies 2A doesn't mean it supplies 5v while you're drawing 2A. As you draw more current, the voltage can drop and this is why you are seeing an 'undervolt' warning.

Also, setting the clock to 1510MHz does not mean your Pi is running at 1510MHz.

I'm not confusing any of them. I happen to have an A2 degree in electromechanics, and know what I'm talking about (unlike a certain user (in my block list), who seems to just enjoy ridiculing people. Take a hint, PeterO).
At a higher load, voltage drops. Chargers with low amp rating, drop voltage quickest. Chargers with high amp rating, maintain voltages best.

Although I won't deny that it is possible that this charger triggers the undervolt warning because it provides 5V at low or zero load, instead of full load. They are Chinese products after all, so maintaining a standard might not be priority for some companies.

[jamesh]

Although I won't deny that it is possible that this charger triggers the undervolt warning because it provides 5V at low or zero load, instead of full load. They are Chinese products after all, so maintaining a standard might not be priority for some companies.

This is well documented on here - many chargers (vs power supplies) drop voltages under higher loads, especially the cheaper ones.

Do yourself a favour and if the use case permits it, get a official power supply. They are very good, with very thick wires which ensures minimal voltage drop. Our PS's also are rated at 5.1V at the wall, so voltage drops over the cable brings them in to spec at cable end.



And can I remind everyone to keep it polite.

[ProDigit]

Note that if the warning is being reported, you may be more susceptible to SD card corruption, random RAM corruption, USB communication failures etc. All of these may be happening right now but you may not be noticing them. Until one of them hits something critical. Then you will.

Thanks, yes, I read up on that.
So far it passes CPU stress tests, io tests, and glxgears.
I've also done some sdcard writes, installed programs (from wifi), and no errors yet.
I do have an arm and sdram overvoltage setting at +2.

I don't know if this is what prevents errors from happening.
But if it does, perhaps low voltage warnings can be replaced with a bump in overvolting arm and sdram, up to right under where the warranty bit is set?

[PeterO]

I'm not confusing any of them. I happen to have an A2 degree in electromechanics, and know what I'm talking about (unlike a certain user (in my block list), who seems to just enjoy ridiculing people. Take a hint, PeterO).

I'm sorry, but when you write

At best, I'd say arm freq 1,2Ghz throttling at 2A, and 600Mhz when voltage drops further (1,5A? I believe I've booted the pi with a 1500mA charger before.

you are mixing up all sorts of things....
" throttling at 2A " is meaningless. Throttling takes place at a particular CPU temperature, not at a particular CPU current. CPU temperature depends on other things besides current draw and has time dependent part due to thermal lag and heat sink efficiency.

"when voltage drops further (1,5A? " Voltage is measured in Volts not Amps, so that is meaningless....

Maybe you know what you are on about, but you're not writing it in a way that is at all understandable.

What is an "A2 degree" ?

PeterO