Arduino Serial Monitor Example
Start with a board-only sketch and inspect a repeating message and counter.
Wire it up
Disconnect power before changing connections. Follow terminal names rather than wire colors.
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The complete sketch
unsigned long counter = 0;
void setup() { Serial.begin(9600); }
void loop() {
Serial.print("Hello Circuitera #"); Serial.println(counter++);
delay(1000);
}
The launch buttons use this same code and a matching saved circuit.
Build it step by step
Open a complete project
Launch in Simulator creates a separate Uno sketch and its matching wired circuit. Existing sketches are preserved. Press Run to compile and execute.
Explore the live circuit
Open the simulator serial output and watch the counter advance once per second.
Try it on hardware
Disconnect power while wiring. Match terminal names in the table, select the exact board, Verify, then connect and upload. Check component ratings and power requirements first.
Understand the sketch
UART output
Serial.begin sets the rate. print leaves the cursor on the line; println ends it. Simulated serial output needs no physical cable. Hardware Serial Monitor needs a permitted port and matching baud rate.
If something is different
No hardware output
Upload first, connect Serial Monitor at 9600 baud, and close other programs using the port.
Expected output and tested scope
The Serial Monitor receives repeated Hello Circuitera messages with an increasing counter.
Version 1 · Last source- and build-matched test: 2026-10-25. Actual shipped AVR-GCC WASM compilation and Uno AVR engine execution; no physical hardware test.
Supported tutorial target: Arduino Uno R3 / ATmega328P. Compile: PASS · Modeled execution: PASS. Other boards require a separate review of pins, voltage, libraries and the exact build profile.