fahadraza007
Posts: 3
Joined: Thu Jun 30, 2016 4:13 pm

Powering RPI through PWM PI hat

Mon Jul 25, 2016 8:30 pm

Hi,
I have question regarding powering on RPI through PI hat. I want to get rid of micro usb and want jack that goes in PI hat. Can i power up RPI through pi hat?
Thanks

NatePiVision
Posts: 72
Joined: Fri Apr 29, 2016 5:38 am
Location: Pittsburgh
Contact: Website

Re: Powering RPI through PWM PI hat

Tue Jul 26, 2016 6:02 am

Actually I have the same question but it's not specific to any hat. Is it possible to power on a Raspberry Pi 3 (or any other model) through the GPIO pins or any means other than the micro usb connection? I am making my own hat and want to know if I can avoid the need for the microusb all together because it makes things much cleaner.

Thanks
Current Pi based projects:
https://github.com/nategreco/DAPrototype - Advanced Driver Assist System (ADAS)
https://github.com/nategreco/StereoVisionTest - Stereo vision (CM3) test setup

Videos:
https://youtu.be/WRAR0lgYsj8
https://youtu.be/SyvCJLRw1UQ

geoffr
Posts: 89
Joined: Wed Aug 22, 2012 11:25 am
Location: Melbourne, VIC

Re: Powering RPI through PWM PI hat

Tue Jul 26, 2016 6:40 am

You can provide a Pi power through the 5V pins on the GPIO. What you need to remember is that you are then bypassing the protection on the power supply input of the Pi. That means your Pi becomes a lot easier to fry. It probably would be advisable to consider whether you should include over-voltage and current protection as part of your design.

NatePiVision
Posts: 72
Joined: Fri Apr 29, 2016 5:38 am
Location: Pittsburgh
Contact: Website

Re: Powering RPI through PWM PI hat

Tue Jul 26, 2016 10:32 am

Hi Geoffr,

Thanks for the feedback, that's good information. I'm ultimately working towards a pcb that will run a compute module (patiently waiting for CM 3 to come out) so I think that'll need to be incorporated anyways in the end. I'm going to give it ago with the 5V pins. Is there any difference between pins 2 and 4 (ex, pin 2 is RPi Pwr and pin 4 is USB).

Thanks,
Current Pi based projects:
https://github.com/nategreco/DAPrototype - Advanced Driver Assist System (ADAS)
https://github.com/nategreco/StereoVisionTest - Stereo vision (CM3) test setup

Videos:
https://youtu.be/WRAR0lgYsj8
https://youtu.be/SyvCJLRw1UQ

fahadraza007
Posts: 3
Joined: Thu Jun 30, 2016 4:13 pm

Re: Powering RPI through PWM PI hat

Tue Jul 26, 2016 2:46 pm

Hi geoffr,
Thanks for your reply. can you explain that what's the benefit of data wires in micro usb cable in powering RPI.

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davidcoton
Posts: 5131
Joined: Mon Sep 01, 2014 2:37 pm
Location: Cambridge, UK
Contact: Website

Re: Powering RPI through PWM PI hat

Tue Jul 26, 2016 5:03 pm

fahadraza007 wrote:Thanks for your reply. can you explain that what's the benefit of data wires in micro usb cable in powering RPI.
None whatsoever -- on the official PSU there are no data wires. But detachable cables may be moved to other uses where the data wires are required.
Location: 345th cell on the right of the 210th row of L2 cache

geoffr
Posts: 89
Joined: Wed Aug 22, 2012 11:25 am
Location: Melbourne, VIC

Re: Powering RPI through PWM PI hat

Wed Jul 27, 2016 12:31 am

NatePiVision wrote:Hi Geoffr,

Thanks for the feedback, that's good information. I'm ultimately working towards a pcb that will run a compute module (patiently waiting for CM 3 to come out) so I think that'll need to be incorporated anyways in the end. I'm going to give it ago with the 5V pins. Is there any difference between pins 2 and 4 (ex, pin 2 is RPi Pwr and pin 4 is USB).

Thanks,
No difference. As a general rule you should use both. What gets trickier is the fact that the GPIO connector has multiple ground pins. It is probably better to use as many as possible to ensure that you don't land up with any undesirable current flows through the ground plane.

One of the projects I have built (still needs a case) is an AirPlay receiver. I used a Pi Zero and pHAT DAC plus a board I built myself to provide an on/off switch. That board is stacked in the middle. Oh - I haven't built any protection into that board - I probably should have!
Image
https://twitter.com/gmrza/status/751394945911574528

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davidcoton
Posts: 5131
Joined: Mon Sep 01, 2014 2:37 pm
Location: Cambridge, UK
Contact: Website

Re: Powering RPI through PWM PI hat

Wed Jul 27, 2016 8:33 am

geoffr wrote:You can provide a Pi power through the 5V pins on the GPIO. What you need to remember is that you are then bypassing the protection on the power supply input of the Pi. That means your Pi becomes a lot easier to fry. It probably would be advisable to consider whether you should include over-voltage and current protection as part of your design.
The power protection circuit of the Pi3B is shown here. Ideally any power supply working through the GPIO connector should replicate this, or something equivalent. Strictly an external D5 and C1 are not necessary for a Pi1/2/3, since they exist in the right place on board. The perfect diode block was introduced on the B+, an equivalent is strongly recommended if using a barrel connector or any other source that could have reverse polarity. The critical part in all cases is the polyfuse F1.

The Pi0 schematic isn't published, but it appears not to have any power protection. If you add a polyfuse, the equivalent of D5 is essential for over-voltage protection.

Finally, prevention is better than cure. Try not to connect the wrong voltage, as electronic components can fail faster than a fuse reacts.
Location: 345th cell on the right of the 210th row of L2 cache

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