uVision debugger fails

[dale-lyons]

When the instructions:

file:STM32F4_Power_functions.cpp
line:95
PWR->CR |= PWR_CR_CWUF;
__WFI(); // sleep and wait for interrupt

are executed while debugging in uVision5 the debugger loses its connection
to the target and stops.

I am using STLINK-Utility to program a STM32F4 Discovery board and a full
Keil/MDK/ARM toolchain to build netmf 4.4

I really don't know if this is a configuration problem on my part or not. This setup was working
for me for months now then this just started happening.

I tracked it down to this code and when I remove the PWR->CR |= PWR_CR_CWUF;
the debugger then works fine and I can continue working.

I've done this same exercise on different (new) boards with the same results.
Different computer same result.

cheers
dale

Spoke too soon,
the WFI instruction is causing the problem. As soon as it executes the debugger loses it.

One odd thing, I can single step the instruction no problem, however letting it
execute full speed causes the debugger to break.

I am stuck now, trying to figure away around this issue so I can debug.
thanks
dale

[smaillet-ms]

Every SOC is a bit different with respect to power management and Debug logic. Generally a uVision (or other debugger tool) script is run when connecting the debugger to set control registers to prevent full deep power-down that would disable the debugger hardware. Exactly what that script should be is sadly not consistent, and in my experience is often difficult to find in the docs. If the SOC has FULL support in MDK then you can typically create a simple app with an empty main() in uVision and it generally will be created with the necessary scripts you can copy.