OnOff Shim when used with official Raspberry Pi 7" Display


#1

In my project, I am powering my Raspberry Pi via the 5v and GND pins of the Raspberry Pi display (as per this https://cdn.shopify.com/s/files/1/0174/1800/files/how_to_assemble_the_rpi_touchscreen_display.jpg ).

If I put the On Off shim in, is it correct to assume it will still be able to shutdown and power up using the button? Due to constraints of the case I built I can’t plug the Power supply into the Shim. I understand that the screen will continue to receive power but I guess that’s the case when someone does a shutdown in software too right?


#2

No, unless the power goes through the On Off SHIM it’s impossible for it to fully cut power to the Pi, which means the Pi never completely powers off and wont start back up again.

You will be able to shut down, but that will just leave your Pi in a state of limbo until power is cut and restored.


#3

Thanks @gadgetoid, that then begs the question, has anyone driven the Pi Display via the On Off Shim ? I see two options,

  1. Power the display directly
    Then use the Display’s Power out (USB) to power the OnOff shim. Then draw wires from OnOff shim to Pi 5v and GND.

  2. Power the On Off shim directly and somehow power the Display from the On Off shim. Draw wires from Shim to Pi for GPIO,
    So slightly off track question is can the Pi Display be powered by the OnOff shim via the 5v and GND pins that usually power the Pi or is the Vin and Vout separate on the Pi Display controller board?


#4

OnOff Shim is good for up to 2.5A so it should be enough to power the display. I’m not sure if having the display in circuit would cause any problems with the on/off functionality, but I can’t see why. I could certainly rig up a test on Monday.

You can solder +5v and GND jumpers onto the Pi and hook them up to the display, although that’s obviously semi-permanent.


#5

Ooh, so if I power the display via its 5V and Gnd pins it will work (option 2 above)?


Well, I am going to try it out now.

All I have to do is solder the stacking header on the shim and Jumper them to the Pico HAT?


#6

Should work- although I’ve never tested it so I don’t know if the official display might introduce any weirdness. It shouldn’t since it will be isolated from any power source.


#7

Boo yeah! It works!

Wall wart connected to PowerBoost
Powerboost to OnOff Shim
OnOff shim to Pi
Pi to Display adapter

Everything works. Nothing soldered to the board.

I am getting a low power flashing occasionally. Wonder if it is the drop across Powerboost + OnOff shim. But I won’t be bitcoin mining on this one so should be fine ;-)

Cheers

Thanks a ton @gadgetoid !