This is a mother-of-all interface boards I designed for my 737 overhead panel. Features: - Raspberry Pi Zero W as the microcontroller, pluggable into the PCB (Note: Male Pins soldered BELOW the Pi, not above). - 192 switched inputs (expandable to 256) - 128 LED outputs (expandable to 224), up to 70mA per channel, current limit controllable in groups of 16 (no resistors needed) - 16 channel PWM outputs for controlling servos - 48 7-segment character displays - 8 14-segment alphanumeric displays - 24 GPIO, interruptable - 8 channel analog inputs - Optional Real-Time Clock - Original RPi GPIOs exposed for future expansion Wiring is via 2x8 headers, so you can used 16-wire ribbon cables and easy-to-crimp IDC connectors at the controller end. For the panel end you can either strip the ribbon cable and solder direct to components, or attach a connector as appropriate. Testing is not complete. I will update here as I check and build up the software. Project blog is at http://blog.shahada.abubakar.net/tag/piioboard. Change History: V2.3 - Matrix: Some of the diodes were in the wrong positions. The V2.2 board works, just that the diode was not next to the pins it serves. Fixed. V2.2 (what I use) - Fixed Trimmer Pot connected wrongly, using max, instead of needle. - Fixed HT16K33 module too narrow. V2.1 - place a dot on header pins to indicate pin 1 location. - Fixed P29 label obscured - Add a GPIO controlled LED. - Fixed buzzer should be active type, needs a transistor and current limited LED. - Fixed serious problem with pi connector: - Pi headers reversed, original PCB component was meant for it to be mounted upside down. - GPIO numbering wrong, assumed W.Pi numbering whereas component was BCM. - Added socket for holtek HT16K33 module (removed two MAX7229CNG). V2.0 - initial version