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why STM32F407 descovery flashed software takes effect after replugging the cable

I am using Keil to flash the software to my stm32f407 discovery. But the software only starts working when i pullout the JLINK cable and plug it again. Why is that? Thanks.

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Andy Neil over 3 years ago in reply to rocko874 +1 verified

rocko874 said: they say that its about the index variable being local you've missed the point. Did you follow the link I gave? The compiler sees your loop as totally pointless, so is perfectly entitled...
Robert McNamara over 3 years ago in reply to rocko874 +1

The compiler will not optimize out __NOP() intrinsic instructions. Change your loop from for(uint32_t i=0;i<500000;i++){} To for(uint32_t i=0;i<500000;i++) { __NOP(); }

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0 rocko874 over 3 years ago in reply to Andy Neil

So every variable has to volotile now?
I tried to write a function with a loop and it canceled it in optimisation too.
What could be done other then using volotile?
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0 rocko874 over 3 years ago in reply to Andy Neil

So every variable has to volotile now?
I tried to write a function with a loop and it canceled it in optimisation too.
What could be done other then using volotile?
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0 Andy Neil over 3 years ago in reply to rocko874

rocko874 said:
So every variable has to volotile now?

No - it's just a kludge to get your busy-loop delay working.

rocko874 said:
I tried to write a function with a loop and it canceled it in optimisation too

re-read the linked posts - you need to understand that this is expected behaviour when you write useless loops.

In particular: https://www.avrfreaks.net/comment/3078001#comment-3078001 - the bit, "what a 'C' program is actually about"
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