Detect sound using ESP32 and notify over WiFi

• esp32_sound_detector - ESP32 code for detecting noise using KY-038 and sending a UDP packet over WiFi
• notifier - Python server that waits for the UDP packet and sends a desktop notification

1. Install esp-idf
   • An AUR package for Arch Linux is available esp-idf
2. Install toolchain

   # By default installs to $HOME/.espressif
   /opt/esp-idf/install.sh esp32

3. Load environment variables

   . /opt/esp-idf/export.sh

4. Build and flash using idf.py commands

   cd esp32_sound_detector
   
   # Set the basic esp32 as target device
   # Not required on an existing preconfigured project such as this one
   idf.py set-target esp32
   
   # Configure the "WiFi Connection" and "Sound Notification" sections
   # Define the IP and Port to send the UDP packet to
   # Define secret to filter out stray unrelated packets
   #   (If you're sending packets to a broadcast IP the secret can be easily discovered in the LAN)
   # Menuconfig is also be used for switching features and flags such as log level
   idf.py menuconfig
   
   # Build
   # Run the wrapper script instead of `idf.py build` for better LSP support
   ./build.sh
   
   # If you encounter a permission problems under Arch, make sure you are part of the uucp group
   sudo usermod -a -G uucp $USER
   newgrp uucp # or reboot
   
   # Connect the device and flash it, USB serial should be detected automatically
   # flashing will also rebuild automatically if files have changed
   idf.py flash
   
   # Read ESP32 serial output
   idf.py monitor

1. Make sure libnotify is installed as notify-send is used
2. Make sure a notification server such as dunst is installed
3. Test the script with parameters you have configured in the ESP

   # Listen on 192.168.1.1:12100 for packets with secret "ABC" and send the notification "GotIt"
   python notifier/notifier.py 192.168.1.1 12100 ABC GotIt
   
   # Listen on broadcast IP 192.168.1.255:10000 for packets with secret "Secret" and send the notification "OK"
   python notifier/notifier.py 192.168.1.255 10000 Secret OK

4. To setup a SystemD service, copy the supplied template file notifier/sound-notifier.service.template and edit the parameters