experience with zephyr

[biosbob]

i'm starting a dive into zephyr, and was curious about others' experiences with the software....

i'm particularly interested in code size -- basically the output of size on the final executable image....

i'd also like to know more about some realistic applications for neorv32 + zephyr

[stnolting]

Thanks to @henrikbrixandersen we have an initial NEORV32 port for Zephyr 🎉
However, I just played with the default Zephyr examples - so I did not use it for real project (yet). I am more a FreeRTOS guy (this is also something I am facing at work), so I cannot say much about this topic...

Btw, I also really like https://github.com/RIOT-OS/RIOT. Porting that has been on my TODO list for quite a long time 😅

[biosbob]

while Zephyr has lots of support for "tasks" (with many different scheduling policies), each task requires its own stack -- which obviously consumes precious SRAM.... like FreeRTOS (as well as Posix threads), these tasks can block at any point of their execution by waiting on a semaphore/condition/queue/etc.... the per-task stack is used to save/restore registers when switching tasks....

my experience, however, in simple "fringe" devices (eg, wireless sensors) is that blocking tasks can be replaced with a much lighter-weight non-blocking thread which is effectively a very low-priority ISR.... this is a core capability of the EM runtime, where applications can create 10s of threads with only 8 bytes of data overhead....

at some point, we can deep-dive more into this topic -- and explain why FreeRTOS is much to heavyweight for your needs....