Creating a Temperature Alert System

Build a simple temperature alert system that notifies you when the temperature exceeds or falls below a set threshold.

Introduction

In this lesson, you’ll build a practical application: a temperature alert system. This system will notify you when the temperature exceeds a maximum threshold or falls below a minimum threshold.

Step 1: Defining Temperature Thresholds

To create the alert system, define the acceptable temperature range:

MIN_TEMP = 20  # Minimum acceptable temperature in °C
MAX_TEMP = 30  # Maximum acceptable temperature in °C

Step 2: Writing the Alert Logic

Update your script to check if the temperature is outside the defined range and print an appropriate alert message:

import machine
import time

# Initialize the ADC for the temperature sensor
sensor_adc = machine.ADC(4)

# Define temperature thresholds
MIN_TEMP = 20  # Minimum acceptable temperature in °C
MAX_TEMP = 30  # Maximum acceptable temperature in °C

while True:
    # Read the raw ADC value
    raw_value = sensor_adc.read_u16()
    
    # Convert the ADC value to voltage
    voltage = raw_value * 3.3 / 65535

    # Convert voltage to temperature
    temperature = 27 - (voltage - 0.706) / 0.001721

    # Check temperature thresholds
    if temperature < MIN_TEMP:
        print(f"Alert: Temperature is too low! ({temperature:.2f}°C)")
    elif temperature > MAX_TEMP:
        print(f"Alert: Temperature is too high! ({temperature:.2f}°C)")
    else:
        print(f"Temperature is normal: {temperature:.2f}°C")

    # Wait for 1 second before checking again
    time.sleep(1)

Step 3: Running the Script

1. Save the script as temperature_alert_system.py.
2. Run the script in Thonny.
3. Observe the alert messages in the console when the temperature exceeds or falls below the thresholds.

Example Output

When the temperature is normal:

Temperature is normal: 25.84°C

When the temperature is too high:

Alert: Temperature is too high! (31.20°C)

When the temperature is too low:

Alert: Temperature is too low! (19.45°C)

Step 4: Customizing Alerts

You can enhance the alert system by:

1. Adding visual alerts (e.g., blinking an LED when the temperature is out of range).
2. Sending notifications via email or messaging platforms.
3. Logging the temperature data for analysis.

What You’ve Learned

• How to define and use thresholds in your temperature monitoring script.
• How to create a simple alert system for high and low temperatures.
• How to enhance your script with additional features for real-world applications.

In the next lesson, we’ll explore how to expand this system with more advanced features and ideas.

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