With less than 24 hours until the contest closes (assuming I’m getting my timezones right), I’m still surprised that I’ve been able to go from a half-baked idea to a nearly functional device in the span of about two months. That said, there’s still plenty more work to be done to get RetroMedleyCard to the lofty heights of “wafer-thin DOOM”, which then raises the question - what happens next?

Well first of all, I intend to take some time off to focus on getting some other (much simpler) projects across the finish line, and maybe even documented and shared if I’m happy with how they turn out. I’m also considering tidying up and releasing the simple_swd component I wrote for this project as a library, since it could be useful in other projects needing an easy way to access the SWD port of another MCU. Since the last two months have been especially stressful, getting RetroMedleyCard to where it is now, a change of pace and focus is in order…

When I do return to this project, the first port of call would be to address the glaring issues identified in the current RetroMedleyCard iteration, namely a lack of available RAM on the ESP32-S3, fiddly and unreliable PCB connectors, and any silly errors in the PCB layout.

Fortunately, the memory situation should be an easy fix, since Espressif offers the ESP32-S3-PICO-1-N8R8, with a whole 8MB of flash AND PSRAM. Since the current PCB doesn’t use the octal-SPI pins reserved for larger PSRAM devices, it should hopefully be a simple drop-in replacement for the current ESP32-S3FH4R2. I will need to read though the datasheet in detail, but it may be possible to reflow rework the existing PCBs for use as an initial test platform.

Fixing the PCB layout and connectors will necessitate a new PCB iteration, though I will probably want to get the more capable ESP32 SoCs soldered by the fab house anyway, so updating the PCB at the same time shouldn’t be an issue, I could even add actual contact details to the silkscreen and QR code!

The USB-C connectors will likely remain the same for iteration 2, as I still have a full batch worth of USB-C socket PCBs leftover. The 3.5mm TRRS audio socket should hopefully be relatively easy to fix, requiring a separate, dedicated PCB prong for the tip, due to its smaller diameter. The SD card socket can be improved by adding taller components as “pads” to contact the SD card, and relocating some of the pull-up resistors to act as physical barriers which prevent the SD card from being inserted too far. However, the current “pads” (0603 capacitors) are already theoretically the same thickness as the base PCB, so switching to taller components will increase the overall height of the card, which would be pushing the <=2.0mm target.

With the extra PSRAM available, it should be possible to get a much more complete firmware working on the second iteration, using knowledge gained trying to bodge retro-go onto iteration 1. Firmware modifications should be much neater, better targeted to achieve the desired functionality, and with helpful comments explaining what the changes do, so that it can be released alongside the revised hardware design files. This would aim to include functionality which was omitted from the first iteration, such as gamepad support, proper audio output, and the ability to run a larger range of emulators (including DOOM, fingers crossed!).

As for now, this concludes my work towards the 2024 Business Card Challenge, and I wish the best of luck to everyone participating!