PIO I2C Bus Scan with 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:

Buy the components

Raspberry PI Pico

Code

Download code pico-pio-i2c.c

#include <stdio.h>
#include "pico/stdlib.h"
#include "pio_i2c.h"

#define PIN_SDA 16
#define PIN_SCL 17

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

int main() {
  stdio_init_all();

  PIO pio = pio0;
  uint sm = 0;
  uint offset = pio_add_program(pio, &i2c_program);
  i2c_program_init(pio, sm, offset, PIN_SDA, PIN_SCL);

  while (true) {
    printf("\nPIO I2C Bus Scan\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 result;
      if (reserved_addr(addr))
        result = -1;
      else
        result = pio_i2c_read_blocking(pio, sm, addr, NULL, 0);

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

    sleep_ms(2000);
  }
}