The LimeNET-Micro hardware description describes I2C, SPI and UART interfaces in part 3.8. I’d like to understand all of this a bit better and started looking into the Gateware toplevel and pin constraints.
Is there a specification somewhere what the interfaces are used for, and what commands are available?
Are there any debugging/test tools available?
Up to now, I guessed that
RAPI_SPI0 is not used,
RAPI_SPI1 is connected to the Nios II (through an Avalon FIFO), that there are commands that are parsed in
LimeNET-Micro_lms7_trx/software/lms_ctr_app/main.c, and that I2C is not used to communicate between Raspberry Pi and Nios II. I hope that is correct so far, and would appreciate a short confirmation or correction.