Hi, after some time of searching why my printf(%f) code behaves weirdly, I found the Dave's page about Newlib issues, and this fixed my problems. It's a shame ST doesn't fix this ASAP, and keeps the buggy solutions in newer versions (without even placing warnings in the code that would come up during compilation, so the users would know what's going on).
My issue was that printf(%f) sometimes worked, and sometimes showed dumb things, like:
float step = 0.1;
printf("%4.2f", step);
was printing: st.ep (yes, the NAME of the variable instead of its value :D)
But it worked fine if and only if the first call to malloc was from the main function before the FreeRTOS scheduler start.
Using heap_useNewlib.c from Dave's site solved my problem. I use TrueStudio 9.3.0, that provides Newlib 2.5.0, and Dave's code works fine with it, despite the warning that it's for 3.0.0 only.
In the newest CubeMX (5.6.1) there are even options to help implementing that:
- USE_NEWLIB_REENTRANT, which sets the variable for FreeRTOS,
- Use FW pack heap file - which enables/disables generation of heap_4.c.
Too bad the first one is disabled by default. Any reason for this?
Even more too bad, that such critical problem is still not solved several months after reporting.
