Please sir, can I have a bigger screen....?

Probably not a bigger TFT screen on the board - but how about a really big screen?

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There’s been lots of requests for a bigger screen, and I’ve had to push back on this. It’s pretty hard to drive high res TFT screens from an MCU and get good performance.

I did briefly consider looking at VGA output from the ESP32, but who actually has a VGA monitor nowadays? I even purchased a VGA to HDMI converter to try some things out, and my success has been limited. Mostly due to the fact that I’m using the ESP32-S3.

What I have been thinking about are the potential options for the “expansion port” on the latest design.

This breaks out a bunch of interesting pins - including the SD Card, the display and some spare pins.

I got to thinking - what if we could plug an RP2040 into this? That would make HDMI output available!

Here’s a little proof of concept running - it’s currently running the amazing pico-zxspectrum emulator from fruit-bat on the Pico and I’m running some simple code on the ESP32 that exposes the keyboard over I2C. I’ve hacked fruit-bat’s code so it reads from I2C - and it works!

It’s pretty amazing that it works given all these jumper wires!

At present, it’s running a complete emulator and SD Card on the breadboard. So we’re only using the ESP32 to process the touch keyboard.

But with the expansion port we could have a nice little RP2040 board that either - runs an emulator - outputing to HDMI and using the SD Card and speaker on the board.

Or, even more interestingly, acts as a “graphics card” for the ESP32.

Now I have been considering integrating this into the actual PCB, but I think I need to focus on actually getting that finished and shipping - I’m also trying to keep the BOM cost down to keep the price at a sensible level.

So, I think an expansion card for HDMI output could be a really nice add on for the future.

What do you think?