ProtocolsQUICK REFERENCE
UART
Cross TX and RX, share ground and agree on the serial format.
01Three-wire link
- Crossed data
- Device A TX → device B RX; device A RX ← device B TX.
- Ground
- Join GND unless using a purpose-built isolated interface.
- Voltage
- Use compatible logic levels or level shifting in each required direction.
02Serial settings
- Format
- Both ends must match baud, data bits, parity and stop bits; 9600 8N1 is a common starting point.
- Arduino
- Serial.begin(9600); Serial.println("ready");
- Pico
- UART(0, baudrate=9600, tx=Pin(0), rx=Pin(1)).
03Debug
- No text
- Check crossed wiring, ground and the selected serial port.
- Garbled
- Check baud/format, voltage levels and clock accuracy.
- USB conflict
- Uno/Nano D0/D1 and typical ESP32 UART0 are shared with USB programming/debug.