Hello! I need help with a coding project. I'm trying to get an XIAO RP2040 to send a message to another RP2040 through serial, and then have the receiving RP2040 display a message on the serial monitor. I need the code to be in Arduino CPP, not Micropython.

ChatGPT said: Hey! I’ve got you covered. Here's a basic example of how to set up serial communication between two XIAO RP2040 boards using Arduino C++.

🧩 What You’ll Need: Two XIAO RP2040 boards

Common ground connection

TX from sender to RX of receiver, and vice versa (optional if unidirectional)

✅ Sender Code (Transmitter) This XIAO RP2040 sends a message through the Serial1 port:

void setup() {
  // Start Serial1 for TX/RX communication
  Serial1.begin(9600);
}

void loop() {
  // Send a message
  Serial1.println("Hello from Sender!");
  delay(1000); // send every second
}

✅ Receiver Code (Receiver) This board reads from Serial1 and displays it via the USB Serial monitor:

void setup() {
  // Start USB Serial for debug output
  Serial.begin(9600);
  // Start Serial1 for receiving messages
  Serial1.begin(9600);
}

void loop() {
  if (Serial1.available()) {
    String msg = Serial1.readStringUntil('\n');
    Serial.println("Received: " + msg);
  }
}

🔌 Wiring Notes

Pin Sender Receiver

TX (D6) → RX (D7)

GND ↔ GND

TX (Sender) → RX (Receiver)

Make sure the voltage levels match (they do on RP2040s).

Use Serial1 which maps to D6 (TX) and D7 (RX) on the XIAO RP2040.