Complete KiCad project (including schematics, footprints and layouts) is available here.
For this implementation, we’ve used the UART interface of the Raspberry-Pi (GPIO Pins #14 and #15), two additional GPIO Pins to control elements of the circuit ( GPIO Pins #22 and #23 ), a 3v3 output power pin, and a ground pin.
There are still 24 available GPIO pins, which can be used to control additional modules. The SPI & I2C interfaces are also fully available, if we’d like to use them with other modules.

Schematic Circuit

Schematic

PCB Layout

Front Layer :

Front Layer PCB

Back Layer :

Back Layer PCB

3D View :

3D View #1 3D View #2 3D View #3