Shaoting-Feng/LoRa-MAC-Layer ? reverse-engineered prompt

Build me a working LoRa MAC layer demo for an ultra low power SDR setup.

I want a transmitter side and a receiver side, both controlled by an MSP430 board talking to an SX1276 LoRa board over SPI, with a simple desktop interface in Qt that talks to the transmitter MCU over UART. The app should let me send messages, support broadcast, handle retries when a packet times out, and show basic status so I can see what is being sent and received.

Please also include the MCU firmware for both sides, with the frame format, sleep and duty cycle behavior, and the state machine logic needed for sending and receiving. Make the UI clean and easy to use, and keep it working on Linux too. If anything is unclear, look up the current docs online and make sensible choices.