FREE SIMULATOR EXAMPLE · BEGINNER

ESP32-C3: Serial Hello

This example needs no wiring at all: the ESP32-C3 prints a boot banner once, then a numbered heartbeat — “[1] Uptime: 1s” — every second to the Serial Monitor at 115200 baud. It is the fastest way to confirm the emulated UART and your monitor settings agree before you build anything bigger.

Board	ESP32-C3 (RISC-V single-core, 160 MHz)
Difficulty	beginner
Category	communication
Libraries	None — just the Arduino core
Runs in	Sensbench browser simulator — free, no account

The exact circuit you get when you open this example — already wired, ready to run.

The sketch

// ESP32-C3 — Serial Hello World
// Open Serial Monitor at 115200 baud

void setup() {
  Serial.begin(115200);
  delay(200);
  Serial.println("=== ESP32-C3 Serial Demo ===");
  Serial.println("RV32IMC @ 160 MHz — QEMU libqemu-riscv32");
  Serial.println();
}

int tick = 0;

void loop() {
  delay(1000);
  tick++;
  Serial.print("[");
  Serial.print(tick);
  Serial.print("] Uptime: ");
  Serial.print(millis() / 1000);
  Serial.println("s");
}

How it works

Serial.begin(115200) starts UART0 at the standard ESP boot baud rate, then a deliberate delay(200) waits before the banner prints — on real hardware that pause gives the USB-serial bridge time to attach so you do not miss the first lines. In the simulator the monitor is already connected, but keep the habit.

The loop is a metronome: delay(1000), increment tick, then a chain of Serial.print() calls assembles one line like [12] Uptime: 12s. Two counters, two meanings — tick counts loop passes, millis() / 1000 counts wall-clock seconds. They agree only because the loop body is nearly instant; add a slow sensor read and they drift apart, which is your first taste of why delay()-based timing does not scale.

Before you build it for real

Get the parts

Related examples

FAQ

Why 115200 baud?

It is the rate the ESP32 family boot ROM uses for its own log messages, so the chip’s output and your sketch share one monitor setting. The UART itself goes far higher, but 115200 is where every tool and tutorial already agrees.

tick and Uptime always match — why keep both?

They match only because this loop does nothing but print. tick counts iterations; millis() / 1000 counts elapsed seconds. Add a blocking call — a sensor read, a network request — and the two numbers separate, which is exactly the lesson the sketch is quietly teaching.