FREE SIMULATOR EXAMPLE · ADVANCED

[Pico] Multi-Protocol Demo

This example runs a six-part bring-up suite on the Raspberry Pi Pico: I2C scan, EEPROM round-trip, RTC probe, SPI loopback, ADC sample, and a GPIO blink — all in one sketch with labeled verdicts in the Serial Monitor. It is the fastest way to prove every peripheral on the RP2040 works.

Board	Raspberry Pi Pico (RP2040 dual-core Cortex-M0+, 133 MHz)
Difficulty	advanced
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

// Raspberry Pi Pico — Multi-Protocol Demo
// Tests Serial, I2C, SPI, and ADC all together

#include <Wire.h>
#include <SPI.h>

void setup() {
  pinMode(LED_BUILTIN, OUTPUT);
  Serial.begin(115200);
  delay(500);

  Serial.println("==============================");
  Serial.println(" Pico Multi-Protocol Demo");
  Serial.println("==============================");
  Serial.println();

  // ── 1. I2C Scanner ──
  Wire.begin();
  Serial.println("[I2C] Scanning bus...");
  int found = 0;
  for (byte addr = 1; addr < 127; addr++) {
    Wire.beginTransmission(addr);
    if (Wire.endTransmission() == 0) {
      found++;
      Serial.print("  Found device at 0x");
      if (addr < 16) Serial.print('0');
      Serial.println(addr, HEX);
    }
  }
  Serial.print("  Total devices: "); Serial.println(found);
  Serial.println();

  // ── 2. I2C EEPROM R/W ──
  Serial.println("[I2C] EEPROM test at 0x50...");
  Wire.beginTransmission(0x50);
  Wire.write(0x00); // register 0
  Wire.write(0x42); // data
  Wire.endTransmission();
  delay(5);

  Wire.beginTransmission(0x50);
  Wire.write(0x00);
  Wire.endTransmission();
  Wire.requestFrom(0x50, 1);
  if (Wire.available()) {
    byte val = Wire.read();
    Serial.print("  Wrote 0x42, Read 0x");
    Serial.print(val, HEX);
    Serial.println(val == 0x42 ? " — OK" : " — FAIL");
  }
  Serial.println();

  // ── 3. I2C RTC ──
  Serial.println("[I2C] Reading DS1307 RTC at 0x68...");
  Wire.beginTransmission(0x68);
  Wire.write(0x00);
  Wire.endTransmission();
  Wire.requestFrom(0x68, 3);
  if (Wire.available() >= 3) {
    byte sec = ((Wire.read() & 0x7F) >> 4) * 10 + (Wire.read() & 0x0F);
    byte min2 = Wire.read();
    (void)sec; (void)min2;
    Serial.println("  RTC responded OK");
  }
  Serial.println();

  // ── 4. SPI Loopback ──
  Serial.println("[SPI] Loopback test...");
  SPI.begin();
  SPI.beginTransaction(SPISettings(1000000, MSBFIRST, SPI_MODE0));
  byte tx = 0xAB;
  byte rx = SPI.transfer(tx);
  Serial.print("  TX: 0x"); Serial.print(tx, HEX);
  Serial.print("  RX: 0x"); Serial.println(rx, HEX);
  SPI.endTransaction();
  Serial.println();

  // ── 5. ADC ──
  Serial.println("[ADC] Reading analog channels...");
  analogReadResolution(12);
  int a0 = analogRead(A0);
  Serial.print("  A0 (GP26): "); Serial.println(a0);
  Serial.println();

  // ── 6. GPIO ──
  Serial.println("[GPIO] Blinking LED...");
  for (int i = 0; i < 3; i++) {
    digitalWrite(LED_BUILTIN, HIGH);
    delay(200);
    digitalWrite(LED_BUILTIN, LOW);
    delay(200);
  }
  Serial.println("  3 blinks done");
  Serial.println();

  Serial.println("=== All protocol tests complete ===");
}

void loop() {
  // Heartbeat
  static unsigned long last = 0;
  if (millis() - last >= 3000) {
    last = millis();
    Serial.print("[Heartbeat] ");
    Serial.print(millis() / 1000);
    Serial.println("s");
  }
}

How it works

The sketch runs six tests in sequence inside setup(), each labeled with a banner: an I2C bus scan, an I2C EEPROM write/read at 0x50, a DS1307 RTC probe at 0x68, an SPI loopback at 1 MHz, a 12-bit ADC read on A0, and a three-blink GPIO check on the built-in LED. Every test prints its own verdict, so you can see exactly which subsystem passed or failed.

The EEPROM test is the sharpest one: it writes 0x42 to register 0 and reads it back, printing OK only if the value survived the round trip. The SPI test loops 0xAB and checks the echo. The ADC test just samples A0 — with nothing connected the reading is noise, which is the expected pass condition at this stage.

Before you build it for real

Get the parts

Related examples

FAQ

Why combine everything into one sketch?

It is a bring-up test: one upload, one serial window, and every peripheral the Pico offers gets exercised in sequence. If the whole suite passes, the board, core, and your wiring are all sound — the same idea as a factory self-test. It also demonstrates that I2C, SPI, ADC and GPIO can coexist on one chip without fighting.

What is the heartbeat for?

The loop is deliberately empty — the tests ran once in setup(). The heartbeat keeps the sketch alive visibly: if the board resets or crashes, the heartbeat stops, and the serial output tells you where it died.