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.
Engineer
Looks good, but I’ll add a quick log file so I can see when alerts are received. Also, I’ll catch JSON errors in the Flask route to avoid crashes if the Pi sends malformed data. Let me know if you need the logger setup.