BLE Exposure Notification Beeper

Allows you to build a simple device that beeps and flashes an LED whenever someone using a COVID-19 warning/tracing app that uses Bluetooth LE Exposure Notifications, like the german Corona-Warn-App, is seen nearby.

Notifiers (nearby devices with a warning app) are remembered for 20 minutes so it only beeps for newly detected ones. Note that the IDs will change every 15 minutes or so for privacy reasons, triggering new beeps.

Build your own

You need

Any ESP32 board (like a WEMOS D32 or TTGO ESP32, preferrably with a LiPo battery controller).
A 3V piezo buzzer (a simple speaker or headphones will also work).
Optionally a LED.
Optionally a small 1-cell LiPo battery.
A nice case :)

Wiring

ESP32 pin	goes to
GPIO 0	LED (+)
GPIO 2	Buzzer (+)
GND	LED (-), Buzzer (-)

Pins can easily be changed in code (src/main.cpp).

Flashing the ESP32

If you don't have PlatfomIO installed, you can flash precompiled binaries directly with esptool.py.

Using PlatfomIO

Simply open the project and upload.
Or via command line: platformio run -t upload
You may need to install the arduino-esp32 platform and the lbernstone/Tone library first.

Using esptool.py

Install esptool.py: pip install esptool
- On Windows, you might need to install python (2 or 3) first.
Download the latest binaries.
cd into the directory where the (unzipped) binaries are located.
Flash using the following command:

esptool.py \
--chip esp32 \
--baud 460800 \
--before default_reset --after hard_reset write_flash -z --flash_mode dio --flash_freq 40m --flash_size detect \
0x1000 bootloader_dio_40m.bin \
0x8000 partitions.bin \
0xe000 boot_app0.bin \
0x10000 firmware.bin

You may need to define your serial port with something like --port "/dev/cu.usbserial-0001" if esptool.py doesn't automatically find it.
Some ESP32 boards require you to press (and hold) the flash button until flashing begins.