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

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);
  }
}