Email alerts on sensor thresholds in Raspberry Pi

Introduction

We use email alerts to get notified quickly when a sensor detects something important. This helps us act fast without watching the sensor all the time.

You want to know if the temperature in your room gets too high or too low.

You want to be alerted if a door sensor detects it was opened.

You want to get a message when soil moisture is too dry for your plants.

You want to monitor water level and get an alert if it gets too low.

You want to receive a warning if smoke or gas is detected by a sensor.

Syntax

Raspberry Pi

import smtplib
from email.mime.text import MIMEText

# Set sensor threshold
THRESHOLD = 30

# Function to send email alert
def send_email_alert(sensor_value):
    sender = '[e-mail]'
    receiver = '[e-mail]'
    password = 'your_email_password'

    subject = 'Sensor Alert'
    body = f'Sensor value reached {sensor_value}, which is above the threshold.'

    msg = MIMEText(body)
    msg['Subject'] = subject
    msg['From'] = sender
    msg['To'] = receiver

    with smtplib.SMTP_SSL('smtp.gmail.com', 465) as server:
        server.login(sender, password)
        server.sendmail(sender, receiver, msg.as_string())

# Example sensor reading
sensor_value = 35

if sensor_value > THRESHOLD:
    send_email_alert(sensor_value)

Replace [e-mail], [e-mail], and your_email_password with your actual email details.

This example uses Gmail's SMTP server with SSL on port 465.

Examples

This checks if the sensor value is above the threshold and sends an email alert if true.

Raspberry Pi

if sensor_value > THRESHOLD:
    send_email_alert(sensor_value)

This is a simple function structure to send an email alert with the sensor value.

Raspberry Pi

def send_email_alert(sensor_value):
    # email setup and sending code here
    pass

Sample Program

This program checks if the sensor value is above the threshold. If yes, it prints a message about sending an alert email. The actual email sending line is commented out to avoid accidental emails during testing.

Raspberry Pi

import smtplib
from email.mime.text import MIMEText

THRESHOLD = 30

def send_email_alert(sensor_value):
    sender = '[e-mail]'
    receiver = '[e-mail]'
    password = 'your_email_password'

    subject = 'Sensor Alert'
    body = f'Sensor value reached {sensor_value}, which is above the threshold.'

    msg = MIMEText(body)
    msg['Subject'] = subject
    msg['From'] = sender
    msg['To'] = receiver

    with smtplib.SMTP_SSL('smtp.gmail.com', 465) as server:
        server.login(sender, password)
        server.sendmail(sender, receiver, msg.as_string())

sensor_value = 35

if sensor_value > THRESHOLD:
    print(f"Sensor value {sensor_value} is above threshold {THRESHOLD}. Sending alert email...")
    # Uncomment the next line to actually send the email
    # send_email_alert(sensor_value)
else:
    print(f"Sensor value {sensor_value} is within safe limits.")

Important Notes

Make sure to enable 'less secure app access' or use an app password if using Gmail.

Test your email sending code carefully to avoid spamming yourself.

You can replace the sensor_value with real sensor readings from your Raspberry Pi.

Summary

Email alerts help you get notified instantly when sensor values cross limits.

You write a function to send emails using SMTP and call it when needed.

Always test with print statements before sending real emails.