Waveshare Pico LCD 1.8 + ESP32-C6-Pico intermittent REPL

[konomikitten]

I've contacted Waveshare about this but they don't seem to have any ideas so far, so I'm asking here. When I connect the Waveshare Pico LCD 1.8 to the Waveshare ESP32-C6-Pico the REPL just doesn't seem to respond and I have to unplug it and replug it until it does.

The LCD uses GPIO Pins 21,20,19,18 which seems fine but it also uses 8 and 9. 8 is labelled as having rom/rgb led and 9 is labelled as boot. I'm not sure if this could cause the REPL to be intermittent or not though, does anyone else have any ideas? Other than the REPL acting up every other aspect of both the LCD and the ESP32 work fine.

MicroPython v1.25.0 on 2025-04-15; ESP32C6 module with ESP32C6
Type "help()" for more information.

[peterhinch]

The ESP32-C6-Pico is a strange beast: an ESP board with a name which relates to the Pico and a pinout exhibiting superficial similarities. A fair question to ask of Waveshare is "Is it designed to work with their Pico LCD displays?".

I have my doubts. The display expects to see an SPI interface on pins 14 and 15. These are GPIO (10, 11) on the Pico and (23, 22) on the ESP board: the latter are not listed as SPI pins.

You could try to make it work with SoftSPI but decent display performance relies on fast SPI transfers (>=30MHz). The reset and backlight pins are mapped to extended I/O. Some coding will be needed to adapt the display driver. A Pico W or a Pico 2 W might be more promising targets.

[konomikitten]

I did manage to get it work but because the inbuilt led is on the GPIO 8 it blinks like crazy, I imagine the GPIO 9 being boot is probably causing the REPL issues. I'm going to contact Waveshare and ask them to remove the Pico LCD 1.8 as a compatible product because it really isn't as far as I can tell.

[peterhinch]

I'm going to contact Waveshare and ask them to remove the Pico LCD 1.8 as a compatible product

The Pico LCD 1.8 is compatible with the Pico series*.

Unfortunately the ESP32-C6-Pico is not a compatible replacement for the Pico. I don't know how they are marketing this, but they should make clear that though it is a similar form factor the resemblance ends there.

* While I haven't used this display I have experience with other sizes of their Pico LCD displays which work well.

[konomikitten]

Yeah unfortunately the ESP32-C6-Pico links to a bunch of compatible products all for actual Raspberry Pi Picos while not being completely pin compatible. One of those products is the Waveshare Pico LCD 1.8.

[konomikitten]

Okay so I might've been barking up the wrong tree, I used jumpers to remap GPIO 8 and 9 to GPIO 22 and 23 and the light is still blinking and I still have the problem of REPL not coming up sometimes when plugging in USB. So I went back and only connected the power jumpers in this case VBUS, VSYS and GND and the REPL still misbehaves and I have to replug until it starts working. disconnecting the LCD completely and the problem vanishes. Ideas?

[konomikitten]

I think this might be an issue with MicroPython itself, is there anyway to debug the REPL not coming up? I'm comparing versions right now.

[konomikitten]

Okay so it gets stranger... I can actually input commands like ctrl+c and ctrl+d and they work I just get no output from the board itself when the REPL misbehaves... I'm at a loss now hopefully someone here will have a way to go about figuring out the problem.

[konomikitten]

I can also blindly type ctrl+c import machine machine.reset() and the REPL is working again...

[peterhinch]

I'm at a loss now hopefully someone here will have a way to go about figuring out the problem.

Unless someone has one of these boards, who also has electronics experience and testgear, it's not clear how we can help. It is possible there is a hardware fault, or a design fault. Does Waveshare provide any binaries you can run to test the board?

[konomikitten]

I think there's some Arduino code I could run I'll have to look into it, I'm also checking different USB ports and I have a Raspberry Pi Pico 2W clone from Pimoroni coming soon so I should have plenty of options for finding out what is going wrong.