OUTAGE

Power outage notifier, based on an ESP32 client and a PHP web server

Table of Contents

1. How it works
2. Requirements
3. Set up
4. Credits

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How it works

The client device sends a request to the server at every specified interval while it is online. Whenever the server detects a gap in pings larger than the interval length, it notifies the user of a possible power outage.

• A client device sends an HTTP request to a PHP script at a given interval
• Every time the PHP receives a ping, it notes down the timestamp
• A cron job pings another PHP script, which checks if the difference between current time and last device ping has exceeded its interval length
• If that is the case, then the device has stopped pinging. PHP will send an email to the user, then notes down that it has already done so
• If pinging returns after the outage email has been sent, another email is sent to the user to notify them that the device has come back online

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Requirements

• Client side
  • an ESP32 Dev Kit
  • Arduino IDE
  • stable power and Wi-Fi connection
• Server side
  • PHP web server
  • Cron job
  • SMTP (to send emails)
  • PHPMailer
  • stable power and internet connection

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Set up

• Server side

  • Download PHPMailer from GitHub, rename the folder to PHPMailer-master and put it under /server/
  • Enter SMTP information in /server/secret.php
  • Change email information in /server/emailUtils.php
  • The default ping interval is 3 minutes. If you want to change it, do so on INTERVAL_SECONDS in /server/cron.php
  • A template is provided for a device in /server/devices.json and /server/stamps.json. You can modify the device ID (1-9999) and the email addresses to send notification
  • Host the contents of /server/ on a PHP server
  • Note the path to /server/ping.php on your server. Format it as https://{your_url}/{path}/ping.php?id={device_id}. You will need this later as "ping URL"
  • Set up a Cron job with interval */3 * * * * if your interval is every 3 minutes. The cron job should fetch the path to /server/cron.php (you can use curl)
  • If your server doesn't work with cron jobs, you can also use cron-job.org

• Client side

  • Connect the ESP32 to a computer, and download necessary softwares from the Arduino IDE's board manager
  • Copy and paste the code from /client/ping.cpp
  • Enter the Wi-Fi name in SSIDNAME, password in PASSWORD, and the ping URL in ENDPOINT. (Make sure the id is present in the URL)
  • Change the ping interval on INTERVAL_SECONDS to match the server side, if you have modified it
  • Upload the code on to the ESP32
  • Unplug the ESP32 and plug it into a power source, and make sure that during normal operations, both the red and blue LEDs are lit up

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Credits

Made by Mu Leelawat. Contact information can be found on my website.

Fun fact: This project is live, up and running at my house!