Python新手求助：实现HX711称重10839-10850范围邮件告警

Hey Jon, let's work through this problem to get your email alert working reliably!

The core issues you're facing are:

• HX711's occasional spikes triggering false alerts when using a simple upper threshold
• Missing the exact value 10840 because of your 5-second sampling interval

Here's a robust solution that combines range checking with a debounce mechanism to filter out spikes, plus a flag to avoid duplicate emails:

Step-by-Step Solution #

1. Use a range condition instead of exact value matching to catch all valid readings in your target window.
2. Add a debounce counter to ignore single-sample spikes (since HX711 spikes are usually short-lived).
3. Keep a state flag to ensure you only send one email per valid "weight in range" event (instead of spamming emails while the weight stays in the window).

Modified Code Example #

import smtplib
# Assume your HX711 and LCD setup code is above this

# Initialize global state variables (put these outside your main loop)
email_sent_flag = 0  # 0 = not sent, 1 = already sent for this event
stable_reading_count = 0
# Require 3 consecutive valid readings to trigger (adjust based on your spike frequency)
required_stable_readings = 3

# Inside your main sampling loop:
w = hx711.get_weight()  # Get current weight reading
hx711.power_down()
hx711.power_up()

# Check if weight is in your target range
if 10839 <= w <= 10850:
    stable_reading_count += 1
    # Only trigger if we have multiple consecutive valid readings AND haven't sent the email yet
    if stable_reading_count >= required_stable_readings and email_sent_flag == 0:
        # Update LCD
        lcdclear()
        lcdprint("Fuel Cell Has Been Replenished")
        setCursor(0,1)
        lcdprint("Sending Email")
        
        # Send email with error handling
        try:
            server = smtplib.SMTP('mail.jon2.com', 587)
            server.starttls()
            server.login("jon2@jon2.com", "aaaa1111")
            # Properly format the email with a subject line
            msg = "Subject: Fuel Cell Replenished Alert\n\nFuel Cell Has Been Replenished"
            # Correct sendmail parameters: sender, recipient, message
            server.sendmail("jon2@jon2.com", "jon1@jon2.co.uk", msg)
            server.quit()
            email_sent_flag = 1  # Mark email as sent to avoid duplicates
            print("Alert email sent successfully!")
        except Exception as e:
            print(f"Failed to send email: {str(e)}")
            # Reset flag if sending failed so we can try again
            email_sent_flag = 0
else:
    # Reset counters if weight is outside the range
    stable_reading_count = 0
    # Optional: Reset the flag if you want to re-trigger the email if weight re-enters the range later
    # email_sent_flag = 0

Key Improvements Explained #

• Range Check: 10839 <= w <= 10850 ensures you don't miss valid readings because of sampling timing.
• Debounce Counter: stable_reading_count filters out single-sample spikes—only consecutive valid readings trigger the alert. Adjust required_stable_readings (e.g., to 5) if you still see false triggers.
• State Flag: email_sent_flag prevents multiple emails from being sent while the weight stays in the range. If you want to re-alert if the weight leaves and re-enters the range, uncomment the email_sent_flag = 0 line in the else block.
• Proper Email Format: Added a subject line and corrected the sendmail parameters (your original code was missing the recipient argument in the right place).
• Error Handling: Wrapped the email logic in a try-except block to catch issues like network errors, and reset the flag if sending fails so you can retry.

Extra Tips #

• Calibrate your HX711 module regularly to reduce baseline noise and spikes.
• If you notice frequent spikes, consider adding a low-pass filter to your weight readings (e.g., average the last 5 readings instead of using a single sample).

内容的提问来源于stack exchange，提问作者Jon