How to connect a ADAFRUIT16x32 RGB LED Matrix Panel to a Raspberry Pi 4

As Clem says, it's very likely that the logic levels are incompatible. A lot of these 5V display boards use older logic ICs with non-3.3V-compatible inputs, and you'll either get nothing on the display, or stuff that looks like it sometimes works with corruption.

There's also a high chance of power related issues, or software issues, if you're trying with a different version Pi. So, it's not surprising it isn't working. But, without photos showing your setup, including power source, and the output you got when installing and running the code (since you mention it did give you issues) it isn't possible to troubleshoot those aspects easily.

Hi Leo,

It's great you've got the level converters, and if you're getting some output, then there's also a chance that the driver or interface software is likely to be functioning on the Pi 4 too.

However, that Adafruit level converter circuit is bad.. they ought to have 100nF capacitors close to the supply pins on the chip. I couldn't see them on your photo either, so it is worth adding them if they are missing.

The 2A PSU may not be enough (check the specs for the display boards, in case it specifies the recommended minimum) but since you're only trying to illuminate a few lines, this hopefully isn't an issue.. your multimeter is reporting a good value.

so you are suggesting 100nf cap across the power and ground pins on the ICs.

Yes, with a short path, i.e. point-to-point on top or the underside. Like this:

Also, the wiring is extremely long, and that can have issues at the speed at which the Pi's interface will be controlling that display panel. Hopefully the capacitors can help, but also a few hours spent shortening and tidying the wiring could be useful. The jumper cables are being used in an unusual way, they don't need to be soldered onto the proto board. Instead, it could be better to get a length of insulated wire and strip, twist and solder it, because then the wiring can be of the right length. If you need jumper sockets/plugs at the display end, then you could cut one end off from the jumper wire (or buy the jumper sockets and manually crimp them to your wire - that needs some more equipment though, although it is possible to get away with soldering the crimp terminals to the wire).

If you need to extend a wire, then rather than chaining the jumper wires, another technique is to cut the jumper wire in half, then solder a wire, and then put heatshrink over it (needs a hot air tool, but a candle can be used).

Anyway, the above is just some tips for prototyping slightly better, if the capacitors do not help.

Here is an example of wiring onto a proto board, you can see all the on-board wiring is short, and any off-board wiring is reasonably tidy (the example here is using screw terminals and also header pins and jumper wires, but you could also directly solder off-board wiring too, it is just less maintainable, and might need some glue or tying down for strain relief). The 100nF capacitors are blue.

Here's another example using breadboard but the concepts are similar. When using a breadboard, solid core wire can sometimes be easier. Again the 100nF capacitors are there, in blue. Also you can see some jumper wires, that were made by using crimps, and then putting heatshrink sleeving around them. This way the off-board wiring can be made to the desired length.

Also, the wiring is extremely long, and that can have issues at the speed at which the Pi's interface will be controlling that display panel. Hopefully the capacitors can help, but also a few hours spent shortening and tidying the wiring could be useful. The jumper cables are being used in an unusual way, they don't need to be soldered onto the proto board. Instead, it could be better to get a length of insulated wire and strip, twist and solder it, because then the wiring can be of the right length. If you need jumper sockets/plugs at the display end, then you could cut one end off from the jumper wire (or buy the jumper sockets and manually crimp them to your wire - that needs some more equipment though, although it is possible to get away with soldering the crimp terminals to the wire).

If you need to extend a wire, then rather than chaining the jumper wires, another technique is to cut the jumper wire in half, then solder a wire, and then put heatshrink over it (needs a hot air tool, but a candle can be used).

Anyway, the above is just some tips for prototyping slightly better, if the capacitors do not help.

Here is an example of wiring onto a proto board, you can see all the on-board wiring is short, and any off-board wiring is reasonably tidy (the example here is using screw terminals and also header pins and jumper wires, but you could also directly solder off-board wiring too, it is just less maintainable, and might need some glue or tying down for strain relief). The 100nF capacitors are blue.

Here's another example using breadboard but the concepts are similar. When using a breadboard, solid core wire can sometimes be easier. Again the 100nF capacitors are there, in blue. Also you can see some jumper wires, that were made by using crimps, and then putting heatshrink sleeving around them. This way the off-board wiring can be made to the desired length.

Great examples shabaz. Good pictures. I am hoping to get a new phone/camera from china that can match the quality...