Embedded C Program for Temperature Monitoring System

An Embedded C program for temperature monitoring reads sensor data using ADC, converts it to temperature, and displays or triggers alerts using printf or output pins; for example, int temp = (ADC_value * 500) / 1023; converts ADC to temperature in Celsius.

Examples

InputADC_value = 512

OutputTemperature = 250°C

InputADC_value = 1023

OutputTemperature = 500°C

InputADC_value = 0

OutputTemperature = 0°C

How to Think About It

To build a temperature monitoring system, first read the analog voltage from a temperature sensor using the ADC module. Then convert this ADC value to a temperature using the sensor's scale. Finally, display the temperature or trigger an alert if it crosses a threshold.

Algorithm

1

Initialize ADC and serial communication

2

Read analog value from temperature sensor

3

Convert ADC value to temperature in Celsius

4

Display temperature value

5

Check if temperature exceeds threshold and alert if needed

6

Repeat the process continuously

Code

embedded_c

#include <stdio.h>
#include <stdint.h>

// Simulated ADC read function
uint16_t read_ADC() {
    return 512; // Example ADC value
}

int main() {
    uint16_t adc_value = read_ADC();
    int temperature = (adc_value * 500) / 1023; // Convert ADC to temperature (0-500°C)
    printf("Temperature = %d°C\n", temperature);
    if (temperature > 100) {
        printf("Alert: Temperature too high!\n");
    }
    return 0;
}

Output

Temperature = 250°C
Alert: Temperature too high!

Dry Run

Let's trace ADC_value = 512 through the code

1

Read ADC value

adc_value = 512

2

Convert ADC to temperature

temperature = (512 * 500) / 1023 = 250

3

Print temperature

Output: Temperature = 250°C

4

Check threshold

250 > 100, so print alert

5

Print alert

Output: Alert: Temperature too high!

Step	ADC Value	Temperature	Output
1	512	-	-
2	512	250	-
3	512	250	Temperature = 250°C
4	512	250	Alert triggered
5	512	250	Alert: Temperature too high!

Why This Works

Step 1: Reading ADC value

The program reads the analog voltage from the temperature sensor using the ADC, which gives a digital value between 0 and 1023.

Step 2: Converting ADC to temperature

The ADC value is scaled to temperature by multiplying by 500 (max temp) and dividing by 1023 (max ADC value), giving temperature in Celsius.

Step 3: Displaying and alerting

The temperature is printed, and if it exceeds 100°C, an alert message is shown to warn about high temperature.

Alternative Approaches

Using interrupt-driven ADC reading

embedded_c

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

volatile uint16_t adc_value = 0;
bool adc_ready = false;

void ADC_ISR() {
    adc_value = 600; // Simulated interrupt ADC read
    adc_ready = true;
}

int main() {
    // Simulate ADC interrupt
    ADC_ISR();
    if (adc_ready) {
        int temperature = (adc_value * 500) / 1023;
        printf("Temperature = %d°C\n", temperature);
        if (temperature > 100) {
            printf("Alert: Temperature too high!\n");
        }
    }
    return 0;
}

This method uses interrupts for ADC reading, which is efficient but more complex to implement.

Using a sensor with digital output (e.g., I2C)

embedded_c

#include <stdio.h>

int read_temperature_sensor() {
    return 75; // Simulated digital sensor reading in Celsius
}

int main() {
    int temperature = read_temperature_sensor();
    printf("Temperature = %d°C\n", temperature);
    if (temperature > 100) {
        printf("Alert: Temperature too high!\n");
    }
    return 0;
}

This approach reads temperature directly from a digital sensor, simplifying conversion but requiring sensor-specific code.

Complexity: O(1) time, O(1) space

Time Complexity

The program runs in constant time since it performs a fixed number of operations per reading without loops.

Space Complexity

Uses constant space for variables; no dynamic memory allocation is needed.

Which Approach is Fastest?

Direct ADC reading with simple conversion is fastest; interrupt-driven or digital sensor methods add complexity but can improve responsiveness or accuracy.

Approach	Time	Space	Best For
Simple ADC read	O(1)	O(1)	Basic temperature monitoring
Interrupt-driven ADC	O(1)	O(1)	Efficient real-time systems
Digital sensor read	O(1)	O(1)	Simpler code with digital sensors