ESP32-PaxCounter/src/i2cscan.cpp

// Basic config
#include "globals.h"
#include "i2cscan.h"

// Local logging tag
static const char TAG[] = __FILE__;

int i2c_scan(void) {

  int i2c_ret, addr;
  int devices = 0;

  ESP_LOGI(TAG, "Starting I2C bus scan...");

  // block i2c bus access
  if (I2C_MUTEX_LOCK()) {

    // Scan at 100KHz low speed
    Wire.setClock(100000);

    for (addr = 8; addr <= 119; addr++) {

      Wire.beginTransmission(addr);
      Wire.write(addr);
      i2c_ret = Wire.endTransmission();

      if (i2c_ret == 0) {
        devices++;

        switch (addr) {

        case SSD1306_PRIMARY_ADDRESS:
        case SSD1306_SECONDARY_ADDRESS:
          ESP_LOGI(TAG, "0x%X: SSD1306 Display controller", addr);
          break;

        case BME_PRIMARY_ADDRESS:
        case BME_SECONDARY_ADDRESS:
          ESP_LOGI(TAG, "0x%X: Bosch BME MEMS", addr);
          break;

        case AXP192_PRIMARY_ADDRESS:
          ESP_LOGI(TAG, "0x%X: AXP192 power management", addr);
          break;

        case QUECTEL_GPS_PRIMARY_ADDRESS:
          ESP_LOGI(TAG, "0x%X: Quectel GPS", addr);
          break;

        case MCP_24AA02E64_PRIMARY_ADDRESS:
          ESP_LOGI(TAG, "0x%X: 24AA02E64 serial EEPROM", addr);
          break;

        default:
          ESP_LOGI(TAG, "0x%X: Unknown device", addr);
          break;
        }
      } // switch
    }   // for loop

    ESP_LOGI(TAG, "I2C scan done, %u devices found.", devices);

    // Set back to 400KHz
    Wire.setClock(400000);

    I2C_MUTEX_UNLOCK(); // release i2c bus access
  } else
    ESP_LOGE(TAG, "I2c bus busy - scan error");

  return devices;
}