Engineer & Coder
Engineer
Hey, I've been thinking about setting up a small autonomous monitoring system for our lab. It would use a temperature sensor and a microcontroller to trigger an alert if it goes beyond a threshold, and I want to tie that into a notification system that your code can listen to. Do you have any experience with that?
Coder
Sounds like a solid idea. I’ve built a few projects like that before – usually a cheap MCU like an ESP32, a DS18B20 or LM35 for temperature, and then a small server that listens for a webhook. You can push the data over MQTT or even HTTP POST to a Python listener that fires off an email or Slack message when the threshold’s crossed. Let me know what platform you’re using and I can sketch out the code for you.
Engineer
Great, I’m running the monitoring unit on a Raspberry Pi running Raspbian. I’ll use a DS18B20 sensor on a 1‑Wire bus, connect it to the Pi’s GPIO, and write a small Python script that polls the sensor every minute. Once the reading exceeds the set threshold I want the script to send an HTTP POST to my central server’s /alert endpoint. The server will parse the payload and trigger an email. Let me know what library or framework you’d recommend for the Pi side, and I can start putting the code together.
Coder
I’d just use the built‑in w1‑therm kernel support and a tiny Python script. Enable the 1‑wire interface in raspi‑config, then in Python use the w1thermsensor package to read the DS18B20. For the POST just import requests and send a JSON payload. Something like:
```python
from w1thermsensor import W1ThermSensor
import requests, time
sensor = W1ThermSensor()
threshold = 30.0 # degrees C
url = 'https://your‑server/alert'
while True:
temp = sensor.get_temperature()
if temp > threshold:
payload = {'temp': temp, 'time': time.time()}
try:
requests.post(url, json=payload, timeout=5)
except requests.RequestException:
pass # maybe log the failure
time.sleep(60)
```
That’s it—no heavy frameworks needed, just the two libs. If you want more resilience you can add a small retry loop or log to a file. Let me know if you need the server side too.
Engineer
Sounds solid. On the server side I’ll just set up a tiny Flask route that accepts the JSON and fires an email via SMTP. I’ll keep it stateless and add a quick retry if the network hiccups. Let me know if you need a sample or help with the mail part.
Coder
Sure thing. Here’s a minimal Flask route that pulls the temp, logs it, and sends an email with smtplib. If the send fails it retries a couple of times. Adjust the host/port/password for your SMTP server.
```python
from flask import Flask, request, jsonify
import smtplib
from email.message import EmailMessage
import time
app = Flask(__name__)
SMTP_HOST = 'smtp.example.com'
SMTP_PORT = 587
SMTP_USER = 'user@example.com'
SMTP_PASS = 'secret'
ALERT_TO = 'alert-recipient@example.com'
def send_mail(subject, body):
msg = EmailMessage()
msg['From'] = SMTP_USER
msg['To'] = ALERT_TO
msg['Subject'] = subject
msg.set_content(body)
for attempt in range(3):
try:
with smtplib.SMTP(SMTP_HOST, SMTP_PORT) as s:
s.starttls()
s.login(SMTP_USER, SMTP_PASS)
s.send_message(msg)
return True
except Exception as e:
if attempt < 2:
time.sleep(5) # small back‑off
else:
print('Failed to send email:', e)
return False
@app.route('/alert', methods=['POST'])
def alert():
data = request.get_json()
temp = data.get('temp')
ts = data.get('time')
subject = f'Temperature alert: {temp:.1f}°C'
body = f'Alert triggered at {time.ctime(ts)} with reading {temp:.1f}°C.'
send_mail(subject, body)
return jsonify({'status': 'sent'}), 200
if __name__ == '__main__':
app.run(host='0.0.0.0', port=5000)
```
That should get you up and running. Let me know if you hit any snags.