Carton__
Posts: 2
Joined: Tue Nov 20, 2018 4:29 pm

Powering Raspberry Pi through GPIO and Pi Touchscreen compatibility

Tue Nov 20, 2018 4:53 pm

Hi everyone,

I'm planning to start a new project with a Raspberry Pi 3 B+ or A+ and the official Raspberry Pi Touchscreen. I've never used this screen so I have a question about it and can't find any answer here or on Internet.

For this project, I will design a daughter board that supplies power at different voltages (12, 5 and 3.3VDC). The power will be supplied to the Pi through the GPIOs (pins #2 and #6 if I'm right) from the 5VDC of this external daughter board. I'm already using this kind of setup on a UDOONeo and it's working fine.

But, now, I need to know if it's ok for the Pi to have its power supplied from the GPIOs and then have the Pi Touchscreen draining power from the GPIO too. I won't use USB at all to supply power to the Pi or the touchscreen.

Is it possible to do this ?

Thanks to all who will take a little of their time to answer me. If something is not clear (bad explanations or English), please let me know.

Best regards

Carton__

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Burngate
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Location: Berkshire UK Tralfamadore
Contact: Website

Re: Powering Raspberry Pi through GPIO and Pi Touchscreen compatibility

Tue Nov 20, 2018 7:20 pm

Yes, But ...

Yes, pin 2 (and 4) is connected directly to the 5v rail, and pin 6 (and others) is ground, though I would avoid calling them GPIO pins - they're not.
In fact it would be better to refer to the whole connector as the GPIO header, to avoid confusion.

Supplying the Pi with 5v through pins 2 & 6 will work, but it by-passes the protection circuitry, so is somewhat less safe.

The recommended way is to supply power to the screen, which then supplies power through the header to the Pi.
Powering both through the header should work equally well. Just don't let your 12v get anywhere near the Pi or screen, and don't try to feed your 3v3 into the header - the Pi's regulator is delicate enough as it is.

LordThingol
Posts: 6
Joined: Mon Nov 19, 2018 4:26 pm

Re: Powering Raspberry Pi through GPIO and Pi Touchscreen compatibility

Tue Nov 20, 2018 7:44 pm

You could also try soldering some wires with an old micro usb connector (old smartphone psu), use it to power the Pi, then use the GPIO header to power the screen.

Personally i power my screen through the header and power it through the PI with a micro usb connector from a 2.5 A / 5.1 V PSU.

Just be careful which pins you use - https://pinout.xyz/#

gkaiseril
Posts: 578
Joined: Mon Aug 08, 2016 9:27 pm
Location: Chicago, IL

Re: Powering Raspberry Pi through GPIO and Pi Touchscreen compatibility

Tue Nov 20, 2018 9:01 pm

Both the Pi and touchscreen have usb power sockets. So you cn get a Y usb cord and power both from the power supply. The also have pins for 5 vdc and ground an you can use jumpers to power the device not powered by the usb power supply.
f u cn rd ths, u cn gt a gd jb n cmptr prgrmmng.

Carton__
Posts: 2
Joined: Tue Nov 20, 2018 4:29 pm

Re: Powering Raspberry Pi through GPIO and Pi Touchscreen compatibility

Wed Nov 21, 2018 1:58 pm

Thank you for your fast answer and advice !

I really need to power the Pi and the Pi touchscreen with the GPIO header. The power will come from the 5V of a daughter board (230VAC -> 5VDC).

As Burngate seems to say it's possible to do so, I will try this solution and keep the forum updated about the experience (because I couldn't find this setup elsewhere).

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