RPi-3 - Power via GPIO

[nickorossa]

Hi

Can someone confirm a RPi-3 can be powered on and run via GPIO (pins 4 & 6)?

Thanks.

Nick.

[DougieLawson]

Hi

Can someone confirm a RPi-3 can be powered on and run via GPIO (pins 4 & 6)?

Thanks.

Nick.

You can, but you risk destroying the machine as it bypasses all of the protection for in the regular supply (using the microUSB). Get more than 5.1V on there and you'll let the magic smoke out.

[nickorossa]

The power circuit I'm looking to drive it with is based on a LM2576T-5, with a 2A fuse in line of the power feed.

Connecting to the GPIO for power, the PI appears to try and start, puts up the colour screen image then "resets" and tries again.

I saw some articles a while back (can't find it now) about certain versions not booting from GPIO, but powering fine once booted.

Nick.

[DougieLawson]

You're wrong, those posts were about back-powering through the USB socket. Not powering through GPIO.

+5V on pin#2 or #4 and GND on pin#6, #9, #14, #20, #25, #30, #34 or #39 will power your machine as long as the power supply is stable and can deliver enough amps.

[Burngate]

The power circuit I'm looking to drive it with is based on a LM2576T-5, with a 2A fuse in line of the power feed.
Connecting to the GPIO for power, the PI appears to try and start, puts up the colour screen image then "resets" and tries again.

Is the LM2576 on a heatsink? 65°C/W junction to ambient means it'll go into thermal shutdown quite quickly.
Is the wire from the regulator to the Pi thick enough?
Is whatever's supplying the regulator man enough for the job?

[nickorossa]

Hi

Heatsink, no not yet.
Yes, it should be.
12v 6a gel battery, so should be man enough for the job.

Nick.

[nickorossa]

My multi-meter readings show 4.98-5.01 as the voltage being supplied to the Pi.

Temperature on the heat sync bit of the LM2576 is around 35 degreesC.

Nick.

[PiiPatient]

Hi

Can someone confirm a RPi-3 can be powered on and run via GPIO (pins 4 & 6)?

Thanks.

Nick.

Well now, someone certainly was burning the candle at both ends last eve now weren't they Nickorossa....Huh... lol

I appreciate your question, just don't know that I have the answer you are looking for. However, I have been running my Touch Screen Powered from the Raspberry Pi3's GPIO Header. https://drive.google.com/open?id=0BwKFp ... VJCcGp5Nkk

Also, I have a schematic, so-to-speak, from a CANAKIT that I bought for my first Raspberry Pi 2 that I owned. Showing the Pin Lay-Out. https://drive.google.com/open?id=0BwKFp ... jNERXJRSlk

[nickorossa]

Well now, someone certainly was burning the candle at both ends last eve now weren't they Nickorossa....Huh... lol

No idea what you mean by this; can only assume you're mixing me up with someone else.

Nick.

[PiiPatient]

Sorry Nick, was just looking at your time stamp and trying to be humorus and thinking I would humour you with my comment. Otherwise, I don't know you from a hole in the wall... take care Nick and have a great evening/morning/daytime, where ever what ever time zone you are in....

[rickticktock]

This is another case where a schematic would be useful. So far as I can tell, all the USB sockets, the +5 GPIO pins and the +5 power input are copper connected.

[drgeoff]

This is another case where a schematic would be useful. So far as I can tell, all the USB sockets, the +5 GPIO pins and the +5 power input are copper connected.

Wrong except for Zero and ZeroW.

On other models the USB sockets and the 5 volt pins on the GPIO header are indeed commoned. But between them and the micro-USB input is a polyfuse whose rating varies with model.

[rpdom]

Wrong except for Zero and ZeroW.

On other models the USB sockets and the 5 volt pins on the GPIO header are indeed commoned.

No, there's a power controller between the board 5V (ie. GPIO) and the USB socket 5V. If you shut down the Pi you'll see that the USB goes dead too. Also it is possible to power off all the USB ports (they are linked together) in software.

[drgeoff]

Wrong except for Zero and ZeroW.

On other models the USB sockets and the 5 volt pins on the GPIO header are indeed commoned.

No, there's a power controller between the board 5V (ie. GPIO) and the USB socket 5V. If you shut down the Pi you'll see that the USB goes dead too. Also it is possible to power off all the USB ports (they are linked together) in software.

Thanks for the correction. I'd forgotten about that controller. It wasn't present on the original RPis. Was it on the 2B that first appeared?

[klricks]

....
Thanks for the correction. I'd forgotten about that controller. It wasn't present on the original RPis. Was it on the 2B that first appeared?

It first appeared as U13 on the B+ in 2014. The current limit was selectable 600 or 1200mA but on later models fixed at 1200mA.