Under voltage on the Pi3

RetroResolution

It may be useful to take a look at a blog post I wrote concerning power supplies for the Pi, and also the link in the article to some illuminating information concerning usb cables - they are not all the same, and getting the right cable can make a huge difference:

Looking after your Pi – Part 1 – The Importance of a Quality Power Supply (PSU)

The section at the foot of the post deals with usb cables in particular.

Riverstorm

@zupi said in Under voltage on the Pi3:

Hey! Thanks. I just used the avoid_warnings=1 only to avoid risks and not void warranty in case of a mistakenly over locking with force turbo accompanied by over voltage. ;)

I might be misreading your post but what those settings do is remove the warnings. It does not prevent them from happening. Using the above options your essentially ignoring the danger warnings of possible problems if that makes sense.

zupi

Or I may be misread your, post.
If
"avoid_warnings=1
Removes overlay warnings"
Then it only removes warnings.
But...
"avoid_warnings=2
Allows turbo even when low-voltage is present"...
Doesn't mean that removes warnings but also does not lower cpu freq leaving turbo on and that avoid_warnings=1 prevents turbo?

I am not sure how it really works and when turbo engages. I just wanted to be on the safe side and not mix any over clocking (voltage) settings with turbo on because I think that removes warranty.

Thanks for clarifying and sorry for the long off topic. ;)

Riverstorm

@zupi said in Under voltage on the Pi3:

Or I may be misread your, post.
If
"avoid_warnings=1
Removes overlay warnings"
Then it only removes warnings.
But...
"avoid_warnings=2
Allows turbo even when low-voltage is present"...
Doesn't mean that removes warnings but also does not lower cpu freq leaving turbo on and that avoid_warnings=1 prevents turbo?

I am not sure how it really works and when turbo engages. I just wanted to be on the safe side and not mix any over clocking (voltage) settings with turbo on because I think that removes warranty.

Thanks for clarifying and sorry for the long off topic. ;)

Good point, I am not completely sure. I pretty much take them at face value. I haven't used avoid_warnings=1 which I would guess is more cosmetic in that it only removes visual warning if it becomes distracting

I do use avoid_warnings=2 which allows turbo even when low-voltage is present. It also removes the warning overlay in the corner or I don't remember seeing being distracting any longer.

How turbo ties in with overclocking is better left to someone with more knowledge. The reason I use avoid_warnings=2 is due to a longer USB cable on one of my setups causing some sputter and so far so good. No crashes or freezes and If it corrupts the card I'll just reimage it. So it works out nicely to have that option.

darthpaul

If I'm still getting the under voltage square after using the new power supply, than I will try the avoid_warnings=2 and see what happens.

zupi

Bear in mind that in pi3 at least, the red led should stay always on when the unit is powered. If under voltage takes place then the red led goes off even with avoid_warnings=1, don't know about =2.

Additionally I am quite confident that, an avoid_warnings=1 is purely cosmetic as Riverstorm pointed out before. I used it in a cousins setup and an old mame game was struggling because of poor voltage by an asus charger with constant red led blinking.

zupi

@RetroResolution thanks! You have some really enlightening articles there.;)

GrethTom

I'm getting the under voltage box at times on Pi 3 with the official power adaptor. Should I be concerned?

dankcushions

@GrethTom yeah. what have you got plugged in to it?

GrethTom

I've got a Xbox 360 Wireless adaptor along with a Wireless keyboard adaptor. I still have Wifi and Bluetooth on as default. Is there much/any saving with turning those two off?

dankcushions

doesn't seem like it should kill the power unless the xbox thing is a beast! yeah, you could turn those onboard things off and i guess that should improve things. presume you're using the newer 2.5A official raspberry pi 3 plug, right?

GrethTom

I bought it at the same time a getting thePi 3 in March from thePiHut. Assume it is the latest one but how do I check?

zupi

According to this...
https://shop.pimoroni.com/products/raspberry-pi-universal-power-supply

White should be 2.0 amp and black should be 2.5 amp.

Riverstorm

I don't know if this will help or not but here's a post I could find on the forums by someone named dom his label is "Raspberry Pi Engineer & Forum Moderator". There's roughly 5 pages of Q&A with it. Maybe we can get a more clear answer to how it works because I am a bit confused now too. It looks like the magic line is 4.65v.

Under Voltage Warnings

The B+ has an under voltage detect trigger which results in the power led going off when voltage drops below about 4.65V.
The signal is also available on a gpio line (GPIO35).

Latest firmware update will display a warning symbol in top right of display when this is detected.
It will also disable turbo mode while the warning is displayed to try to reduce the chances of crashing.

I've also added a warning symbol to the existing over-temperature condition (> 85'C), which also disabled turbo mode.

Currently the symbols are:
Red square: over-temperature
Rainbow square: under-voltage

As usual you can override the behaviour in config.txt if you understand the risks:
avoid_warnings=1 removes the warning overlay.
avoid_warnings=2 additionally allows turbo when low-voltage is present.

For testing you can make the temperature warning trigger more easily with "temp_limit=50".
You can probably trigger the under-voltage check by using an insufficient power supply (perhaps USB socket from PC), or a dodgy micro-usb cable from ebay.

Run rpi-update and report back if it behaves as expected.
You will need a B+ to test the under-voltage state. The over-temperature should work on any Pi.

GrethTom

@zupi said in Under voltage on the Pi3:

According to this...
https://shop.pimoroni.com/products/raspberry-pi-universal-power-supply

White should be 2.0 amp and black should be 2.5 amp.

Blast! I have the white one! Need to make another purchase :(

zupi

I am not sure if this needed. I have the white as well, resellers put them as compatible to flush stocks I guess, and don't have any warnings unless I connect a usb powered 2.5 inch external hard, and only for a second.
I usually have 1 usb wireless keyboard and 1 or 2 usb sticks without problem. Definitely in dark about your situation. :/

GrethTom

@zupi Thanks for the info. Looking at The Pi Hut it does list my power unit as 2.5v. Will have a play with Wifi and Bluetooth settings. Have a feeling my Wireless keyboard dongle could be the cause but would struggle to replace it as it does a good job.

RetroResolution

@zupi cheers, glad they're helpful!

darthpaul

Well, this is my final solution. I am enclosing my Pi in a Gamecube console and am using the original Gamecube power supply which is rated at 12v 3.2 amps. I am lowering the voltage with an adjustable voltage regulator and set the output voltage to 5.25v, so far so good.

Lukasz Wiackow

Power supply is very important. The current 2,5A is not only one parameter you need to guarantee. You need also this two parameters:

linear adjustment +/-2%,
load regulation +/- 5%,
Unfortunately I had to research this detailed information because it wasn't attached to my raspberry pi 3.