ADC interrupt-driven reading in Embedded C

Introduction

ADC interrupt-driven reading lets your microcontroller get analog data without waiting. It helps your program do other things while the ADC works.

You want to read sensor data without stopping your main program.

You need to process analog signals continuously and quickly.

You want to save power by letting the CPU sleep until data is ready.

You have multiple tasks and want ADC readings to happen automatically.

You want to avoid missing fast-changing analog signals.

Syntax

Embedded C

void ADC_Interrupt_Handler(void) {
    // Read ADC result
    uint16_t adc_value = ADC_ReadResult();
    // Process or store adc_value
    // Clear ADC interrupt flag
    ADC_ClearInterruptFlag();
}

// Setup function
void ADC_Init(void) {
    // Configure ADC settings
    ADC_EnableInterrupt();
    ADC_StartConversion();
}

The interrupt handler runs automatically when ADC finishes conversion.

Always clear the interrupt flag inside the handler to avoid repeated triggers.

Examples

Simple interrupt handler that reads ADC value and saves it.

Embedded C

void ADC_IRQHandler(void) {
    uint16_t value = ADC_ReadResult();
    // Store value for main program
    adc_data = value;
    ADC_ClearInterruptFlag();
}

Initialize ADC on channel 0 and enable interrupt-driven reading.

Embedded C

void ADC_Init(void) {
    ADC_SetChannel(0);
    ADC_EnableInterrupt();
    ADC_StartConversion();
}

Sample Program

This program sets up ADC interrupt reading. When ADC finishes, it triggers the interrupt handler, which saves the value and sets a flag. The main program then prints the ADC value.

Embedded C

#include <stdint.h>
#include <stdbool.h>

volatile uint16_t adc_data = 0;
volatile bool adc_ready = false;

// Mock functions to simulate hardware
uint16_t ADC_ReadResult(void) {
    return 1234; // example ADC value
}
void ADC_ClearInterruptFlag(void) {
    // Clear interrupt flag (hardware specific)
}
void ADC_EnableInterrupt(void) {
    // Enable ADC interrupt (hardware specific)
}
void ADC_StartConversion(void) {
    // Start ADC conversion (hardware specific)
}

void ADC_IRQHandler(void) {
    adc_data = ADC_ReadResult();
    adc_ready = true;
    ADC_ClearInterruptFlag();
}

void ADC_Init(void) {
    ADC_EnableInterrupt();
    ADC_StartConversion();
}

int main(void) {
    ADC_Init();

    // Simulate ADC interrupt call
    ADC_IRQHandler();

    if (adc_ready) {
        // Print ADC value
        // In embedded, replace with actual output method
        // Here we use printf for demonstration
        printf("ADC value: %u\n", adc_data);
    }

    return 0;
}

Important Notes

Interrupt handlers should be short and fast to avoid blocking other tasks.

Use volatile variables for data shared between interrupt and main code.

Always clear the interrupt flag inside the handler to prevent repeated interrupts.

Summary

ADC interrupt-driven reading lets your program get analog data without waiting.

Use an interrupt handler to read and store ADC results automatically.

Remember to clear the interrupt flag and use volatile variables for shared data.