Hi everyone! I am Tan, creator of RP2350 GPIO Expansion Card a year ago. After I did that, many people asked me if its for sale. Now I am developing a more “professional” and “cleaner” version that is “cheaper” to mass-produce and with more convenient components/ecosystem, very likely going to promote it as a general purpose debug probe/modular development board also for non-Framework users. I know top-mount makes it not compatible with official Framework case, but its cheaper to produce that way and more sturdy. Also, JST connectors wouldn’t fit as I couldn’t find any middle-mount JST.
I have produced my first prototype some weeks ago and got produced my own qwiic/stemma qt sensors this week. They seem to work fine. It is very thick because it is cheaper and I just wanted to see if those connections and “RESET+BOOTSEL button circuitry that exploits delay via transistors” work fine (yes, as it would be very uncomfortable to unplug/plug the board just to enter bootsel or reset, and as there are no space for 2 side buttons, I put a circuit that allows going into reset then bootsel with single button). I will def go with 0.8mm given being top-mount already makes it hard for a custom expansion card case.
Now I am working on a more refined 0.8mm thick, 4-layer prototype with 3-pin SWD and 4-pin I2C0/UART0. I will share the prototype model once I complete it. I am then planning to start a Crowd Supply campaign and start my own hardware company developing RISC-V based devboards/modules/accessories with this being our plot product.
Anyways, some images:
