Uno R4 · physical Serial1 peers

Two boards exchange bytes over crossed D1 TX and D0 RX wires at 9600 baud, then 1 Mbaud. Select each board in Serial to read the received decimal values. Reset the simulation to repeat; edit the first board’s sketch in Code.

What's on the bench

• 2× Arduino Uno R4
• Battery

How it's wired

• Battery · pos→Arduino Uno R4 · 5v
• Battery · neg→Arduino Uno R4 · gnd
• Battery · pos→Arduino Uno R4 · 5v
• Battery · neg→Arduino Uno R4 · gnd
• Arduino Uno R4 · d1→Arduino Uno R4 · d0
• Arduino Uno R4 · d1→Arduino Uno R4 · d0

The code

This Arduino C++ sketch lives in the Code tab; sign in and press Compile & upload to build real firmware for the emulated board.

// Breadboard UNO R4 P5 solved-pin Serial1 acceptance fixture.

static void exchangeAt(uint32_t baud, const uint8_t *tx, size_t length) {
  Serial1.begin(baud);
  Serial1.write(tx, length);
  Serial1.flush();

  uint32_t started = millis();
  Serial.print(baud);
  while (millis() - started < 20) {
    if (Serial1.available()) {
      Serial.print(' ');
      Serial.print(Serial1.read());
    }
  }
  Serial.println();
  Serial1.end();
}

void setup() {
  Serial.begin(115200);
  static const uint8_t kSlow[] = {0x55, 0x00, 0xff};
  static const uint8_t kFast[] = {0xa5, 0x5a, 0x3c};
  exchangeAt(9600, kSlow, sizeof(kSlow));
  exchangeAt(1000000, kFast, sizeof(kFast));
}

void loop() {}

Firmware licence

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