nickorossa
Posts: 71
Joined: Wed Mar 14, 2012 12:42 pm
Location: Swindon, UK, Planet Earth.

RPi-3 - Power via GPIO

Sun Oct 30, 2016 8:17 am

Hi

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

Thanks.

Nick.

User avatar
DougieLawson
Posts: 39813
Joined: Sun Jun 16, 2013 11:19 pm
Location: A small cave in deepest darkest Basingstoke, UK
Contact: Website Twitter

Re: RPi-3 - Power via GPIO

Sun Oct 30, 2016 9:10 am

nickorossa wrote: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.
Note: Any requirement to use a crystal ball or mind reading will result in me ignoring your question.

Criticising any questions is banned on this forum.

Any DMs sent on Twitter will be answered next month.
All fake doctors are on my foes list.

nickorossa
Posts: 71
Joined: Wed Mar 14, 2012 12:42 pm
Location: Swindon, UK, Planet Earth.

Re: RPi-3 - Power via GPIO

Sun Oct 30, 2016 9:39 am

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.

User avatar
DougieLawson
Posts: 39813
Joined: Sun Jun 16, 2013 11:19 pm
Location: A small cave in deepest darkest Basingstoke, UK
Contact: Website Twitter

Re: RPi-3 - Power via GPIO

Sun Oct 30, 2016 10:01 am

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.
Note: Any requirement to use a crystal ball or mind reading will result in me ignoring your question.

Criticising any questions is banned on this forum.

Any DMs sent on Twitter will be answered next month.
All fake doctors are on my foes list.

User avatar
Burngate
Posts: 6347
Joined: Thu Sep 29, 2011 4:34 pm
Location: Berkshire UK Tralfamadore
Contact: Website

Re: RPi-3 - Power via GPIO

Sun Oct 30, 2016 10:15 am

nickorossa wrote: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
Posts: 71
Joined: Wed Mar 14, 2012 12:42 pm
Location: Swindon, UK, Planet Earth.

Re: RPi-3 - Power via GPIO

Sun Oct 30, 2016 11:12 am

Hi

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

Nick.

nickorossa
Posts: 71
Joined: Wed Mar 14, 2012 12:42 pm
Location: Swindon, UK, Planet Earth.

Re: RPi-3 - Power via GPIO

Sun Oct 30, 2016 12:01 pm

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
Posts: 29
Joined: Tue Dec 30, 2014 1:57 am
Location: Cornwall, Ontario, Canada
Contact: Website

Re: RPi-3 - Power via GPIO

Sun Oct 30, 2016 1:41 pm

nickorossa wrote: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
Certified Glazier/Metal Mechanic, Certified Chef, Hobby Electronics enthusiast. Audiophile

nickorossa
Posts: 71
Joined: Wed Mar 14, 2012 12:42 pm
Location: Swindon, UK, Planet Earth.

Re: RPi-3 - Power via GPIO

Sun Oct 30, 2016 4:14 pm

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
Posts: 29
Joined: Tue Dec 30, 2014 1:57 am
Location: Cornwall, Ontario, Canada
Contact: Website

Re: RPi-3 - Power via GPIO

Mon Oct 31, 2016 2:17 am

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.... :D
Certified Glazier/Metal Mechanic, Certified Chef, Hobby Electronics enthusiast. Audiophile

rickticktock
Posts: 28
Joined: Mon Aug 20, 2018 10:13 am

Re: RPi-3 - Power via GPIO

Thu Nov 01, 2018 12:03 pm

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
Posts: 11106
Joined: Wed Jan 25, 2012 6:39 pm

Re: RPi-3 - Power via GPIO

Sat Nov 03, 2018 8:27 pm

rickticktock wrote:
Thu Nov 01, 2018 12:03 pm
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.
Quis custodiet ipsos custodes?

User avatar
rpdom
Posts: 17552
Joined: Sun May 06, 2012 5:17 am
Location: Chelmsford, Essex, UK

Re: RPi-3 - Power via GPIO

Sat Nov 03, 2018 8:34 pm

drgeoff wrote:
Sat Nov 03, 2018 8:27 pm
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
Posts: 11106
Joined: Wed Jan 25, 2012 6:39 pm

Re: RPi-3 - Power via GPIO

Sat Nov 03, 2018 9:37 pm

rpdom wrote:
Sat Nov 03, 2018 8:34 pm
drgeoff wrote:
Sat Nov 03, 2018 8:27 pm
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?
Quis custodiet ipsos custodes?

klricks
Posts: 7234
Joined: Sat Jan 12, 2013 3:01 am
Location: Grants Pass, OR, USA
Contact: Website

Re: RPi-3 - Power via GPIO

Sat Nov 03, 2018 10:58 pm

drgeoff wrote:
Sat Nov 03, 2018 9:37 pm
....
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.
Unless specified otherwise my response is based on the latest and fully updated RPiOS Buster w/ Desktop OS.

Return to “Interfacing (DSI, CSI, I2C, etc.)”