树莓派PICO使用INA226测量电流和总线电压（4）

这篇文章将写一些题外话，关于INA226的地址，如果不清楚开发板的I2C地址，可以通过总线扫描的办法来获取开发板设定的地址。

#include "hardware/i2c.h"
#include "pico/binary_info.h"
#define I2C_SDA 16
#define I2C_SCL 17

void setup() 
{
    // put your setup code here, to run once:
    Serial.begin( 115200 );
    i2c_init( i2c_default, 100*1000 );
    gpio_set_function(I2C_SDA, GPIO_FUNC_I2C);
    gpio_set_function(I2C_SCL, GPIO_FUNC_I2C);
    gpio_pull_up(I2C_SDA);
    gpio_pull_up(I2C_SCL);
    bi_decl(bi_2pins_with_func(I2C_SDA, I2C_SCL,GPIO_FUNC_I2C));
}

void loop() {
  
  Serial.printf("\nI2C Bus Scan\n");
  Serial.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) {
      Serial.printf("%02x ", addr);
    }

    // Perform a 1-byte dummy read from the probe address. If a slave
    // acknowledges this address, the function returns the number of bytes
    // transferred. If the address byte is ignored, the function returns
    // -1.

    // Skip over any reserved addresses.
    int ret;
    uint8_t rxdata;
    if (reserved_addr(addr))
      ret = PICO_ERROR_GENERIC;
    else
      ret = i2c_read_blocking(i2c_default, addr, &rxdata, 1, false);

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

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