I would like to connect 2 PCBs. On each PCB there is a MCU and each MCU is able to send and receive commands from the other one. Also, PCB1 should supply power to PCB2.
The 2 PCBs are separated by ~100cm and I'm wondering what kind of hardware connection/protocol I should use, knowing that I would like to limit the number of wires between the 2 PCBs.
My first guess was to use UART / RS232, so it can be full duplex, and probably fast enough:
- 1 TX
- 1 RX
- 1 Vcc
- 1 GND
I tested it, and it works (115200 baud rate), there's just a small ~20ms latency getting a reply when sending a request from PCB1 to PCB2. I limited the baudrate to 115200 because I don't want the connection to radiate.
So I was told I could use 2 additional wires and communicate using SPI (which sounded a bit unusual to me when connecting to external PCBs together), so I'm wondering if it's a good idea, what would be the drawbacks?