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:

Pre-requisites

Try these simpler or similar examples:

Buy the components

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);
  }
}

Prototype

A photo of the actual setup.

I2C Bus Scan with RPi pico prototype

Schematic

Wire up the hardware accordingly

I2C Bus Scan with RPi pico schematic

Serial console

Serial output from the firmware.

I2C Bus Scan with RPi pico serial console

Description

This example code does an I2C Bus Scan for the sensors Si7021 and VCNL4000.

The datasheets of the 2 sensors below show that the serial monitor prints are in line with the information in the datasheet.

The I2C address for Si7021 is 0x40.

The I2C address for VCNL4000 is 0x13.

References