Over the years, I come across the need to connect sub systems together with the like of UART, I2C, CAN, LIN, RS485, MODBUS and what not. A few years ago, I also wrote about implementing custom protocols that are simple versions of the previously stated ones and recently jumped into a project that uses a custom LIN implementation. By custom, I means that it does not follow the rules or LIN in terms of communication but uses the same electrical base and some other pieces.
The existing code base is heavily reliant on the processor registers etc and the guy who wrote it can't/won't explain the structure of the system as a lot of it is unplanned, undocumented patches. It works but its a lot of C code mixed with "other things".
My question here is about a standard way of writing things like these. I am talking about implementing multi-byte exchange protocols and what should be the do's don't, correct way, though processes, etc when writing this stuff. Finite state machine code with non-blocking code is where I usually land but I want your thoughts on the process.
What is your way of writing protocols without an OS and how would you accomplish multiple tasks with out the scheduler?
