After this tedious step, he designed a PCB that hosts an Arduino Nano to accept input, two MCP23017 GPIO expanders to give it enough outputs, and CD4066BE CMOS switches to trigger the connections.

The board also includes a USB 2.0 Type-C Host/Device port and PCB antenna for BLE/RF communication. The nanoCH57x development board can be programmed using WCH’s official toolchain, which includes the ...