operate LoRa radio over I2C

Dependencies:   TimeoutAbs lib_i2c_slave_block sx12xx_hal

radio chip selection

Radio chip driver is not included, allowing choice of radio device.
If you're using SX1272 or SX1276, then import sx127x driver into your program.
if you're using SX1261 or SX1262, then import sx126x driver into your program.
if you're using SX1280, then import sx1280 driver into your program.
If you're using NAmote72 or Murata discovery, then you must import only sx127x driver.

This project is used as slave device with i2c_lora_master on raspberry pi. This i2c_lora_slave offloads the real-time requirements onto microcontroller. Also permits multiple slave radio devices connected to master. Radio MAC layer exists on I2C master, along with application layer.

If beacon operation is enabled, I2C functions which access radio chip are blocked while beacon is loaded and transmitted.
See lib_i2c_slave_block for wiring connections.