A test was assigned to me by my professor.
In the test I need to make a STM32f4XX discovery to act like a clock by using the internal RTC and be able to stop it in any time and then the clock be able to resume the count (like a stopwatch).
One of the points of the test is be able to stop the program via the STMCube debugger like the suspend execution or a breakpoint, and when the execution is resumed the "clock" continues in the exact point it left.
Is it possible?
At this point, if I pause the execution in the debugger and then hit resume, the clock "jumps" to another second/minute just like I never paused it. Because the RTC is still running in the background.
According to the Reference manual of the chip, once the RTC starts, it can't be stopped until the chip is powered off.
Is it possible in any way ?
Debug peripheral has special registers where you can program which peripheral to run or stop in the debug top mode. They are called "freeze registers"
So if you want RTC to be stopped when the processor is stopped by the breakpoint you need to program those registers.