Power issues with new Picade and 10-inch screen


#1

Got the new Picade with 10” screen but having lots of issues with power. I’m using the official 2.5A charger but have had to power the LCD independently to get things working. Otherwise it attends to boot and then powers down the display reporting No Signal.

It seems to be an issue with how much power the USB ports supplying power to the LCD can provide as, if I split the charger supply with a microUSB splitter to power the X Hat and LCD independently using the one charger all is ok.

Is there anything I can do to mitigate this?


#2

And typically, no sooner do I post than I find reference to the option to enable “max_usb_current=1” in config.txt.

Did that and issue resolved.


#3

What model Pi are you using? I ask because that only applies to older Pi’s. 2B and earlier I believe?
Have a look here to see what the current limits are.


#4

It’s a Raspberry Pi 3 Model B. Strange as that has fixed the issue.


#5

A Pi 3B is set to 1.2A by default. That max current edit should have no effect. From what I’ve seen posted on the Raspberry Pi Foundation forum anyway.
And just to clarify, when you originally had this issue, you were feeding power in via the Picade X hats micro USB power port? Not via the Pi’s USB power port? I ask because if feeding power in via the X hat, that supplies power to the Pi via GPIO. And that bypasses the Pi’s poly fuse. I do believe the poly fuse is what limits the max current that can be supplied. For a 3B I would think its a 1.2A fuse. Not 100% sure on that though.
I know you have working just curious to what might have caused the issue in the first place. For future reference as they say.


#6

Weirder still. Tomorrow I’ll comment out that line and test but it immediately resolved a no boot issue when I could only start using either separate supplies for pi and lcd or the splitter so very strange.


#7

Yeah, it is weird, that config edit shouldn’t have done anything? I’d do one quick check, if you don’t mind, then do what ever gets it working and enjoy your picade.

I have the Pi foundation 7 inch screen running with a Pi 3B+ . I originally had a 2B, then a 3B before upgrading to the 3B+. I can remeber doing that edit when I had the 2B. I’m running a home made splitter with that setup. They each get their own power feed via their respective Micro USB power ports. I using a 5V 10A supply though, no worries of running out of current, lol. It plugs in via a barrel jack instead of the micro USB. I have my own custom cables wired to the barrel jack receptacle. Its my breadboarding rig and I wanted lots of power for running motors and servos etc.


#8

Commented that line out and it boots fine. Now more confused than ever but it works, that’s the main thing.

Thanks for your help and the info 👍🏻


#9

Maybe it was just a poor connection some place? And moving your cables around fixed it?.
Anyway I’m glad its working, and thanks for doing that check for me. =)
Enjoy your Picade, its on my wish list.


#10

@darreng When you PI booted with the 10" screen did the screen constantly go off and then turn back on reconnecting to HDMI? That is the issue I am dealing with. I’m upgraded but the screen is not staying on in Retropie/Emulationstation.

The odd thing is that if a video screen saver starts it seems to stay on, but if I’m anywhere else it goes on and off…I’ mo sure if this is a settings thing or a driver board thing or what…


#11

Similar but mine wouldn’t boot which is not the same issue. It’d say “ HDMI” then flash to “NO SIGNAL” then repeat. Still none the wiser as apart from adding that line to config nothing changed but it now works. And I have 10 x Plasma buttons installed. Are you using the 2.5A supply?


#12

I’m thinking mine may be due to the usb stick I have in the pi for running the roms off of. It might be drawing too much power. I tried another image and I tried without the USB stick and in both cases it works fine.

So the issue is the USB stick and not enough power on the PI to power everything appropriately.


#13

It does seem to be pushing the limits of 2.5A with a 10-inch display and the plasma buttons. It may come to it that we need to power the LCD with its own supply if we need more juice.


#14

It would be neat if the Picade X HAT took a larger power supply and had passthrough for the screen and then powered the PI normally. Then you’d get the best of the PI, power the screen separately (from a port on the X Hat directly)…

I’m not sure if there is a board out there like that today…


#15

One option is to use this, https://www.adafruit.com/product/1466 with this https://www.adafruit.com/product/2727
I have that 5v 4A supply running one of my Pi builds, and the bigger 10A version running another of my builds.
Pimoroni did at one time have a 5V 3A power supply with a barrel jack, can’t find it at the moment though.


#16

I had this issue when I added 10 plasma buttons to the 10" picade. I found some games that put a lot of white on the screen caused the hdmi to reset issue. I tried a 3amp power supply that helped but didn’t fix the issue.
In the end I found a solution… the picade 10" screen takes its power from the USB lead that plugs in to the PI. theres a lot of electronics in the way of the screen getting its 5v supply. One quick fix is just give the screen its own 5v supply and its sorted, but not as neat.
to get a nice neat fix I found an old microusb lead and cut it and threw away the larger USB A plug. I then soldered the two wires (red to + and black to -) that are now exposed onto the pihat solder points just behind the USB input point - you don’t use the green white leads at all. This fixed it. I think it fixed it because the screen is connecting much closer to the 5v input and avoiding any diodes etc.


#17

Another gotcha is the max USB current for all four ports is limited by the Pi’s poly fuse. The value of that fuse depends on what model Pi you have.


One option is to feed your power in via the GPIO pins. Pin 2 or 4 for the +5V and pin 6 for ground.
Do so at your own risk as it bypasses the poly fuse. I’ve done it on several of my Pi projects.

I’ve also done what cottonpickers did and make my own power cables. I did this on a Pi I have the Pi foundation 7 inch touch screen on. I took two good quality cables and cut the ends off. Then feed my +5V in the red wire and ground to the black. The Data wires I just ignored. Then plugged one into the Micro usb power for the Pi and the other to the power for the screen.