70 cm CW beacon.
Based on STM32 bluepill adrduino board. It basically sends callsign and QTH in morse using SI4432 RF module.
After you press PTT on beacon frequency controller reply with the 3 level of power tone signal and sends "ECHO" in the end. Every 15 minutes Controller sends on air CALLSIGN of repeater or QTH locator by morse code. Schematics https://github.com/diygoodies/RF22CWbeacon/blob/master/Schematics/Schematics.jpg
Progect page http://www.diygoodies.org.ua/?p=1545
USART comamands list: https://github.com/diygoodies/RF22CWbeacon/Commandslist.txt
Code based on BluePill-RTClock-test example of https://github.com/rogerclarkmelbourne/Arduino_STM32 package