Decode ADC Result Using Union Bitfields

Question

Problem: Decode ADC Result Using Union Bitfields. Solve this hands-on electronics task on EWskills.

Accepted Answer

#include 
#include 

typedef union {
    struct {
        uint16_t adc_value : 12;
        uint16_t channel   : 4;
    };
    uint16_t adc_reg;
} ADC_Result;

int main() {
    uint16_t reg;
    scanf("%hx", ®); // Read hexadecimal input

    ADC_Result result;
    result.adc_reg = reg;

    printf("Channel: %u
", result.channel);
    printf("ADC Value: %u", result.adc_value);
    return 0;
}

What is this about?

This mimics a real ADC result register layout where raw analog values and their source channel are packed into one word.

Why it’s important in firmware?

Real hardware often overlays multiple fields into one register
Efficient parsing without using bit masking everywhere
Cleaner access via result.channel and result.adc_value

Solution Logic

Bitfield order matches hardware layout
12 LSBs used for ADC result
Top 4 bits for channel
Union lets us access both the full value and individual fields

71. Decode ADC Result Using Union Bitfields