Multi-channel ADC scanning in Embedded C

Introduction

Multi-channel ADC scanning helps read many sensor signals one after another automatically. It saves time and makes your program simpler.

You want to measure temperature, light, and humidity sensors connected to different ADC pins.

You need to monitor battery voltage and current at the same time.

Your project has multiple analog inputs and you want to read them in a loop without writing separate code for each.

You want to collect data from several sensors quickly and efficiently.

Syntax

Embedded C

void ADC_ScanChannels(void) {
    for (int channel = 0; channel < NUM_CHANNELS; channel++) {
        ADC_SelectChannel(channel);
        ADC_StartConversion();
        while (!ADC_ConversionComplete());
        adc_values[channel] = ADC_ReadValue();
    }
}

This example shows a simple loop scanning multiple ADC channels one by one.

Functions like ADC_SelectChannel and ADC_StartConversion depend on your microcontroller.

Examples

Scan 4 ADC channels and store their values in an array.

Embedded C

for (int ch = 0; ch < 4; ch++) {
    ADC_SelectChannel(ch);
    ADC_StartConversion();
    while (!ADC_ConversionComplete());
    values[ch] = ADC_ReadValue();
}

Using hardware scan mode if supported by your ADC to read multiple channels automatically.

Embedded C

ADC_EnableScanMode();
ADC_SetChannelsMask(0x0F); // Enable channels 0 to 3
ADC_StartScan();
while (!ADC_ScanComplete());
for (int i = 0; i < 4; i++) {
    values[i] = ADC_GetScanResult(i);
}

Sample Program

This program simulates scanning 3 ADC channels and prints their values. Each channel returns a different value to show scanning works.

Embedded C

#include <stdio.h>

#define NUM_CHANNELS 3

// Simulated ADC functions for example
int ADC_SelectChannel(int ch) { return ch; }
void ADC_StartConversion() {}
int ADC_ConversionComplete() { return 1; }
int ADC_ReadValue() { static int val = 100; val += 10; return val; }

int adc_values[NUM_CHANNELS];

void ADC_ScanChannels(void) {
    for (int channel = 0; channel < NUM_CHANNELS; channel++) {
        ADC_SelectChannel(channel);
        ADC_StartConversion();
        while (!ADC_ConversionComplete());
        adc_values[channel] = ADC_ReadValue();
    }
}

int main() {
    ADC_ScanChannels();
    for (int i = 0; i < NUM_CHANNELS; i++) {
        printf("Channel %d value: %d\n", i, adc_values[i]);
    }
    return 0;
}

Important Notes

Make sure to wait for ADC conversion to complete before reading the value.

Some microcontrollers have hardware scan modes to automate this process.

Always check your MCU datasheet for exact ADC functions and registers.

Summary

Multi-channel ADC scanning reads many analog inputs one after another.

It helps collect sensor data efficiently without writing repeated code.

Use loops or hardware scan features depending on your microcontroller.