arduino_st_union_code.c

#include "stdint.h"

typedef union {
    struct{
        uint8_t bit_0: 1;
        uint8_t bit_1: 1;
        uint8_t bit_2: 1;
        uint8_t bit_3: 1;
        uint8_t bit_4: 1;
        uint8_t bit_5: 1;
        uint8_t bit_6: 1;
        uint8_t bit_7: 1;
    };
    uint8_t byte_0;
}st_data;

void setup()
{
  Serial.begin(9600);
  
  st_data my_data;
  my_data.byte_0 = 0xA5; //1010 0101
  
  Serial.println("");Serial.println("Using union to access bit value");
  Serial.print("byte  = ");Serial.println(my_data.byte_0,HEX);
  Serial.println("");
  Serial.print("Bit 7 = ");Serial.println(my_data.bit_7);
  Serial.print("Bit 6 = ");Serial.println(my_data.bit_6);
  Serial.print("Bit 5 = ");Serial.println(my_data.bit_5);
  Serial.print("Bit 4 = ");Serial.println(my_data.bit_4);
  Serial.print("Bit 3 = ");Serial.println(my_data.bit_3);
  Serial.print("Bit 2 = ");Serial.println(my_data.bit_2);
  Serial.print("Bit 1 = ");Serial.println(my_data.bit_1);
  Serial.print("Bit 0 = ");Serial.println(my_data.bit_0);
}

void loop()
{
  
}

c_st_union_code.c

#include "stdint.h"


typedef union {
    struct{
        uint8_t bit_0: 1;
        uint8_t bit_1: 1;
        uint8_t bit_2: 1;
        uint8_t bit_3: 1;
        uint8_t bit_4: 1;
        uint8_t bit_5: 1;
        uint8_t bit_6: 1;
        uint8_t bit_7: 1;
    };
    uint8_t byte_0;
}st_data;

void main()
{
  st_data mydata;

  mydata.byte_0 = 0xA5;
  printf("byte_0 = 0x%02X\r\n",mydata.byte_0);
  printf("bit_7  = %d\r\n",mydata.bit_7);
  printf("bit_6  = %d\r\n",mydata.bit_6);
  printf("bit_5  = %d\r\n",mydata.bit_5);
  printf("bit_4 = %d\r\n",mydata.bit_4);
  printf("bit_3  = %d\r\n",mydata.bit_3);
  printf("bit_2  = %d\r\n",mydata.bit_2);
  printf("bit_1  = %d\r\n",mydata.bit_1);
  printf("bit_0  = %d\r\n",mydata.bit_0);

}