ATSAM + LORA Development in C++

I need to develop a program in C ++ for a custom board (Already designed) based on an Atsamd21j18 and an RN2903 for LORA communication, which performs sensor reading on 4 ports and communicates the reading every 5 minutes by LoRa. The person who will do the work, needs to know microcontroller programming (C ++): Use of pointers, Handling of registers, Use of interrupts, Logical operations, Handling of dynamic memory, handling of clocks and ultra low power consumption, as well as protocols and standards physical communications such as: I2C, SPI, RS232, RS485, LoRaWAN.