where to find STM32 context switch code

[dieter 123]

Posted on June 16, 2017 at 15:24

Hi

when an interrupt kicks in, th current context (core registers , pc and so on are saved). Where in a cube generated project, would I find the context save and restore part? Which registers need to be saved? How many cycles does it need?

[Tesla DeLorean]

Posted on June 16, 2017 at 16:39

The core does this, review documentation for the Cortex-Mx part in question. Either the ARM TRM or books by Joseph Yiu

https://community.arm.com/processors/b/blog/posts/a-beginner-s-guide-on-interrupt-latency---and-interrupt-latency-of-the-arm-cortex--m-processors

 

[Tesla DeLorean · Accepted solution]

Posted on June 16, 2017 at 16:43

The core saves the registers it needs and this matches the ABI for calling C functions, so not special handling is required to use C functions as interrupt handlers. The value of LR passed to the function, is a magic value which upon return tells the core to recover the original context.

Nominally PC, XPSR, R0, R1, R2, R3, R12 and LR