I would like a create a software where some functions (or block) can be programmed later on my micro controller without having to flash the entire software again (flash will be done by a communication interface e.g. SPI). The new blocks will all have the same API (e.g. 5 bytes as arguments, 1 byte returned).
Memory architecture will be organized as shown on this picture: Block architecuture.
Currently, I see no issues if I only use local variables in my new functions, because the variables will be pushed in the stack and will not be initialized in the .bss segment. But if I want to add a static variable in my function, I will have some troubles because the startup code will not initialize this variable in the .bss (or .data) segment.
My question is, is that event possible to implement an architecture like this one in a C code ? If yes, how can I adapt my startup code to initialize my new variables ? Do you think C++ is more appropriate to do such kind of things ?
Thanks a lot !
Include one function in the API which initializes the block. Host must call this function before any other functions of the block.
Also, keep in mind that if you do this, you must also reserve part of the RAM (in addition to flash) for the block, which the host shall not touch. These variables are normally marked as __no_init or something similar to prevent linker even trying to generate initialization data for .data placement.
Language you use (C or C++) most likely won't matter. Memory placement is not feature of either language, but instead is done with compiler extensions and linker features, which are toolchain specific.
