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Keil and STM32 CCM

G G

I am using the STM32F439 which has 64K of CCM (Core-Coupled memory) at address 0x10000000. At the moment I use this for a few variables but I plan to use it for more later. I am having a problem which I believe is caused by the Keil Debugger (ULINK Pro).

If I start a debug session via “Debug->Start/Stop Debug Session” ('Run to main()' is ticked) and examine the CCM memory in the debugger, none of my variables have been pre-initialised and sometimes the RAM just contains a pattern. However, if I then select “Debug->Reset CPU” then everything becomes OK and the variables are all pre-initialised. The problem only occurs when I first start the debug session. Subsequent resets are OK.

Any ideas?

Thanks
Gary

  • 0

    I have found the problem. The RCC AHB1 register has a CCM clock enable (b20) which is not shown in the "System Viewer->RCC". However, it defaults to 1 (enable) following a reset but is 0 (disable) when I first start the debug session due to a bug in my debug script file (.ini).