Serial Monitor

The Serial Monitor shows everything your program sends through Serial. It is the easiest way to see what your program is doing.

Opening the monitor

The Serial Monitor opens automatically when the simulation starts. You can close it and open it again from the ⋮ menu next to ▶: Show Serial Monitor / Hide Serial Monitor. The output is kept while the monitor is closed.

The monitor has two buttons:

New output scrolls into view automatically.

Sending to your program

While the simulation runs, type in the box at the bottom of the monitor and press Enter (or Send). The text arrives in Serial, so your program can read it with Serial.read(), Serial.readString() or Serial.parseInt().

The menu next to the box chooses what is added after your text, as in the Arduino IDE: No line ending, Newline (\n, the default), Carriage return (\r) or Both NL & CR (\r\n).

void setup() {
  Serial.begin(9600);
}

void loop() {
  if (Serial.available()) {
    String text = Serial.readStringUntil('\n');
    Serial.println("You typed: " + text);
  }
}

Printing from code

void setup() {
  Serial.begin(115200);
  Serial.println("Hello from Circzy!");
}

void loop() {
  Serial.print("Temperature: ");
  Serial.println(analogRead(A0));
  delay(1000);
}

The baud rate you pass to Serial.begin() does not matter in the simulator, but use the value your real board needs (9600 or 115200 are common).

Printing from blocks

Use the Serial category of the board group:

• print to Serial text prints a fixed text on its own line.
• print value … to Serial prints a number or the result of a calculation.

When you use these blocks, the generated code calls Serial.begin(9600) for you.

Which port is shown

Boot messages

ESP32 and ESP8266 boards print their ROM boot messages before your program starts, exactly like real hardware:

• ESP32: ets Jul 29 2019 12:21:46 followed by the boot log.
• ESP8266: SDK ver: 2.2.2 … and the PHY version.

These lines are normal and not an error.