I2C Bus Scan with RPi pico

Updated on 2 November 2022

dev board RaspberryPI Pico

firmware C

firmware C++

chip RP2040

chip Si7021

chip VCNL4000

This tutorial is more than 1 year old. If the steps below do not work, then please check the latest versions and the documentations of the individual tools used.

Before starting

Dependancies

Ensure the following dependancies are downloaded and available:

Pico toolchain

Pre-requisites

Try these simpler or similar examples:

Blinky Pico

Buy the components

Raspberry PI Pico

Code

Download code pico-i2c.c

#include <stdio.h>
#include "pico/stdlib.h"
#include "hardware/i2c.h"

#define PIN_SDA 4
#define PIN_SCL 5

bool reserved_addr(uint8_t addr) {
  return (addr & 0x78) == 0 || (addr & 0x78) == 0x78;
}

int main() {
  stdio_init_all();

  // This example will use I2C0 on GPIO4 (SDA) and GPIO5 (SCL) running at 100kHz
  i2c_init(i2c0, 100 * 1000);
  gpio_set_function(PIN_SDA, GPIO_FUNC_I2C);
  gpio_set_function(PIN_SCL, GPIO_FUNC_I2C);
  gpio_pull_up(PIN_SDA);
  gpio_pull_up(PIN_SCL);

  while (true) {
    printf("\nI2C Bus Scan for Si7021 and VCNL4000\n");
    printf("   0  1  2  3  4  5  6  7  8  9  A  B  C  D  E  F\n");

    for (int addr = 0; addr < (1 << 7); ++addr) {
      if (addr % 16 == 0) {
        printf("%02x ", addr);
      }

      int ret;
      uint8_t rxdata;
      if (reserved_addr(addr))
        ret = PICO_ERROR_GENERIC;
      else
        ret = i2c_read_blocking(i2c0, addr, &rxdata, 1, false);

      printf(ret < 0 ? "." : "@");
      printf(addr % 16 == 15 ? "\n" : "  ");
    }

    sleep_ms(2000);
  }
}