evofw3 is an opensource alternative to the HGI80
It uses an avr microcontroller to interface to a TI cc1101 radio.
The code supports 16MHZ atmega328 and 8/16 MHz atmega32u4 platforms. The atmega328 uses a SW Uart to interface to the cc1101 while the atmega32u4 uses a HW Uart.
evofw3 is currently constructed to be built and be programmed with the Arduino GUI. In order to support different platforms it is necessary to use custom board definitions.
You need to be running at least version 1.8.13 of the Arduino GUI.
To access these board definitions in the Arduino GUI
Select File, Preferences
Paste the following link into Additional Board Manager URLs https://raw.githubusercontent.com/ghoti57/evofw3_avr/master/package_evofw3_boards_index.json
Close Preferences
Select Tools, Board, Boards Manager
type evofw3 in the search bar
Click on install in Evofw3 avr boards
Close Boards Manager
In Tools, Board you should now see Evofw3 avr boards.
Use Tools, Board, Evofw3 avr boards to select the appropriate avr controller type
Use Tools, Processor to select the correct speed variant
Use Tools, Pinout to select the appropriate connection variant.
Note that the first time you program an avr controller with evofw3 the COM port may change.
You can buy an Atmega32U4 + 868MHz CC1101 USB stick here https://indalo-tech.onlineweb.shop/