Broken display? ( Little rainbow square in top right corner )


#1

My Picade display has a strange four coloured box (red, blue, cyan, yellow) in the top right corner. What is this? Is it dead pixels or something else?


#2

This is the under-voltage warning- a little icon the Pi shows to tell you that it’s not getting the right voltage. This usually means that your power supply is struggling to keep up with the requirements for the Pi and TFT combo.

You need to use a good, 2A power supply, we recommend the official Pi power supply.


#3

Thank you. I though I had a good PSU as it is rated 5V 2100mA. I’ll try to find a better one?


#4

The rating unfortunately isn’t much of a guarantee if it’s fresh out of an unscrupulous factory in China. But it might be worth probing your setup a bit more to see if anything else is at fault.

How are you supplying power from the LCD to the Pi? The normal GPIO cables, or a USB cable?

What USB peripherals do you have plugged in?

The rainbow square doesn’t actually mean anything is seriously wrong. The Pi can run pretty much fine under voltage- internally it doesn’t even use 5v, but you may have problems with USB peripherals and other things using that 5v supply.

While I wouldn’t ever recommend trying it yourself, I’ve run the Pi and LCD combo down to about 3.8v and it still chugs away fine.

If you want to sweep the problem under the rug, the Pi under-voltage warning can be turned off by adding the following to /boot/config.txt:

avoid_warnings=1

But bear in mind the Pi will still disable “Turbo Mode” under low voltage conditions to ensure it doesn’t crash!