Hey all,
I am wondering about powering the Pi and the RPi display using one power supply - the official supply that comes with the Pi.
This supply would be fed into a splitter cable and from there into the Pi and the Pi display.
Would this be enough power, or would it create problems?
If it helps, I’m running Ropieee and a HAT from Hifiberry.
It should work, that’s what I’m using. You don’t need a splitter though. The display comes with two cables that you’ll use to connect the Pi’s and the display’s power lines. Then, you can plug the power supply in either the Pi’s or the display’s power input port.
https://www.raspberrypi.com/documentation/accessories/display.html#power-the-touch-display
I should have mentioned (and I did in the edit) that I’m also using a HAT from Hifiberry (Digi2 Pro). Someone using the same setup has cautioned against using the power from the GPIO for the display.
Wouldn’t a splitter do the same thing? I don’t know why that would be a problem, but if you don’t want to share power, you can use a different PSU for the display.
I really don’t know if that would be the same thing. I’ve been told that if you use power from the GPIO, you’re bypassing a fuse. How true this is, I couldn’t say. I am currently using two PSUs for the display and Pi, but there’s a case I’m interested in that won’t allow the user to feed two power supplies in – at least not without customization.
Which fuse, on the PI or on the display? If you use GPIO power, you can plug in the PSU in either the PI or the display, so I would think it will go through at least one fuse. This is what they recommend for the display, so you should give it a try.
(The only downside of connecting the PSU to the display is that it’s using a micro-USB, not USB-C, so you’d need an adapter).
I actually have no idea – hence the question. 
I think I might have to do some research on how much power the HAT requires.
It’s a shame they don’t specify power requirements, but by the looks of it, it shouldn’t be too much.
(If I may add, I don’t see any downsides of using a USB port on the PI for connecting to the DAC, so you don’t really need any HATs.)
A fair point. I may take the HAT off to see if Ropieee will then detect the USB output. With the HAT, it says that USB is not detected.
Connect the power supply to the RPi and use jumpers from GPIO to display, there’s no risk other than the PS not being up to the task.
I’m running an RPi4 and an RPi5, both with the official 7"display that way.
On another note, after enabling USB in Ropieee you need to connect and turn on the DAC in question for USB being detected.
You can also leave the HAT connected and use both concurrently as independent endpoints.
While I appreciate all the input here, I still do have the original question – will a cable splitter attached to a single power supply be enough to power the Pi and display?
I suppose I can just try – from what I’ve been reading, there’s no real danger except an error message that says “More POWER! MORE!”
I thought I did in my first post.
I’m not using a splitter though.
Yeah, I do think there will be a difference between powering both with one external supply and powering the display from the GPIO.
I’m not an electronics expert (obviously), but…I can’t help thinking that there will be some difference between piping the power through the Pi and supplying power through the USB input.
If the 5V and GND pins on the GPIO are just part of the input power rails, as I think they are, there’ll be no difference. On the other hand, using a splitter with USB-C may not work if USB-C power is negotiated. I doubt the Pi or this PSU does that, hence the 5V/3A limits. I would still go with the recommended way. I have two in this configuration and they’ve been working for years now.
A quick search seems to indicate the Pi does use PD to negotiate power, so it’s probably a bad idea to use a splitter.
Thanks, I appreciate this.