In this section I'll show how to construct a wall hanging canvas incorporating this 64x64 pixel, 2.5 mm pitch matrix panel:
This matrix panel is 6.3x6.3 inches. An ideal frame for it would be probably 8.5x8.5, or maybe 9x9 inches, but those are not standard sizes. So I'll use a 10x10 inch canvas again here, but try one of the "heavy duty" canvases, which are deeper inside with wider wood framing.
With this configuration, there will not be room for the Matrix Portal to connect directly to the HUB75 connector on the matrix panel. Instead, I'll have to rig up something with the grey IDC ribbon cable....
I'd prefer to have a solder-free way of connecting the Matrix Portal to the gray IDC ribbon cable. I was able to do this using extra-long break-away headers, like this:
Start with 2 rows of 10 pins each and use a pliers or similar tool to push or pull the individual pins through the encasing plastic until they are mostly on one side of the plastic, as shown in the first picture here.
Then push each row of 10 pins through the front of the connector on the Matrix Portal, as shown, so the pins extend out on the side with the ESP32 chip. Push in each pin so it is flush on the side with the plastic parts.
At this point my mind was blown when I realized that the header on the Matrix Portal is 2x10 pins, but the grey IDC ribbon cable is 2x8.
Apparently, four of the sockets on the Matrix Portal header are just for spacing and not electrical contact.
Using the pliers again I removed the 4 outer pins, so we have a 2x8 array of pins that will mate with the IDC ribbon cable.
You need to be careful here to connect the Matrix Portal to the ribbon cable in the correct orientation. It should be hanging the way it normally would - to the left as shown in the picture below:
Next, I set about creating a foam board backing for the matrix panel. In the picture below, I've cut 2 inches off of an 8x10 piece of foam board - making it 8x8 inches.
I've also selected some 1 inch #4 wood screws for the D-rings. After doing the last few builds I started to think that the 4mm spacers are maybe too short, so I'm going to try using the 6mm Pololu spacers this time.
I'll use 3 of the offset clips - two on the bottom and one on top - to hold the foam board assembly in place.
I'll again tape wood screws upside down on top of the matrix panel mounting holes and use this to mark the 4 points on the foam board where I want to feed through nylon screws.
I also cut away two diagonals of the foam board near the top to make it less likely to interact with the hanging wire.
Next I arranged the power cabling for the Matrix Portal and taped it down into a position where the foam board can be set on top.
I used these "low volt" staples here to fix an extension cable in place just below where it needs to plug into the Matrix Portal.
I need to cut away at the bottom of the foam board a bit more to allow for the cable to enter and for the Matrix Portal buttons to be accessible.
I decided to add a little more spacing inside the canvas, adding 2mm spacers. I taped them onto the standoffs so they don't fall off as I'm trying to attach the nylon screws and foam board.
The extra spacing is to get the matrix panel close to the canvas to avoid a blurry image. In retrospect, I would have tried 4mm or 6mm spacers because, as you'll see, the images are a bit blurry with the 2mm spacers.
Update: I tried swapping in the 4mm and 6mm spacers, and they were not enough to eliminate the blurriness. In the end I used 2 of the long nylon standoffs on each mount point (and no spacers) to get a crisp image.
Now the foam board can be screwed on, and then it's just a matter of attaching the offset clips, D-rings and hanging wire.
Note that I cut away a little bit of the foam on top to better fit the third offset clip.
Now it should be ready to hang on the wall and run. As noted earlier, this one came out a little blurry, indicating the matrix panel is too far from the canvas.
I'm going to take it apart again and adjust the spacing inside to get a crisper image....