The main focus was simplicity in design (and manufacturing) while not sacrificing capability wherever possible. Here are the highlights:
- Ability to use headphone and USB Type-C jack while in use. Requires 90 degree adapter or cord
- Power and data delivered through the pogo pins
- Landscape layout for better weight distribution
I forgot to add it to the drawing, but there will also be a cut out for the speaker and microphone.
For the electronics, I plan to construct it with 3 PCBs:
- Main board - Contains STM32G070KBT6 (0.86 USD in quantities > 1000) and pogo pin connector
- Left gamepad board - All buttons and trigger connections for the left half. Connects to main board with an FFC.
- Right gamepad board - All buttons and trigger connections for the righthalf. Connects to main board with an FFC.
Software-wise, my initial plan is for the STM32G070KBT6 to be running firmware compatible with HID over I2C. There is already a kernel driver for this protocol. This firmware needs to be written, but from how I understand it, it doesn't appear to be too complex.
For the housing, I went back and forth on adding a slide out or quick-detach mechanism. In the end, I decided to keep it simple for now and stick with strictly a back cover replacement. If viable sliding/quick-detach mechanisms come out of the keyboard contest, I'd be interested in working with those project leaders to be compatible, allowing you to swap out a keyboard for gamepad and vice versa.