SPI display working on 16GB but not on 8GB

Hello,

We bought about 50 Radxa-Zero v1.51 units. Some of them are 16GB EMMC and some are 8GB EMMC.

We ported the Waveshare 2.13 inch e-paper display driver to the Radxa-Zero. It works nicely for some time already.

Then we made a 6GB image from that.

Interesting enough, we found out that when we flash the image to the 16GB EMMC version of the device, everything works perfectly. But when we flash that same image to the 8GB EMMC version of the device, everything works except the display, which is always blank.

We get no errors, nothing, and everything works, just the display is blank.

Only other thing that I would mention is that initially, the 8GB would not boot at all. Then I found out this post: Debian won't boot on new Radxa Zero where it is said that some devices have a u-boot problem.

Ok, so I followed https://wiki.radxa.com/Zero/dev/u-boot and built u-boot myself. I tested it and it also works perfectly on the 16GB. On the 8GB though, it fixed the boot problem (it started to boot), everything works but blank display.

As we don’t get any errors (when the display wiring is wrong, we get “busy” errors), I am assuming that the wiring is all ok now.

Are not the 16GB and 8GB the very same thing, except for the EMMC size? Both are v1.51.

Any tips are very welcome.

Thank you.

For different production batches some components are exchangeable, it should not cause any additional problems, sometimes there is something faulty on individual board too. If You have more than one - have You tried with more than one? Have You found anything different on 8 and 16 version just comparing them visually?

Interesting, how did you port the driver? I have a couple of these e-ink displays lying around.