How to check at runtime if a debugger is connected ?

[Katzenberger.Michael]

Posted on January 18, 2017 at 19:24

Hi all !

I would like to know if there is a possibility to check at runtime if a debugger is connected to the STM32.

I have to distinguish between two use cases in software:

• application connected to a debugger via 4 pin header (SWD and power 3.3V / GND)  -> no battery protection needed
• appliction is running in normal operation state with connected battery - battery protection (to greater than 3.3V) needed

Any help/hints are appreciated - thanks !

Best regards,

Michael.

#check-debugger-connected-programmatically

[waclawek.jan]

Posted on January 18, 2017 at 19:34

 

[Tesla DeLorean]

Posted on January 18, 2017 at 19:46

I have this for my SWV trace, suggest you look at ITM and SCB registers (not Cortex-M0)

if (*SCB_DHCSR & 1) // Debugger Enabled

http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.ddi0337e/CEGCJAHJ.html

 

//****************************************************************************

static int Debug_ITMDebug = 0;

//****************************************************************************

void Debug_ITMDebugEnable(void)

{

volatile unsigned int *ITM_TER = (volatile unsigned int *)0xE0000E00;

volatile unsigned int *ITM_TCR = (volatile unsigned int *)0xE0000E80;

volatile unsigned int *SCB_DHCSR = (volatile unsigned int *)0xE000EDF0;

volatile unsigned int *SCB_DEMCR = (volatile unsigned int *)0xE000EDFC;

*((u32 *)0xE0042004) |= 0x27;

printf('%08X %08X %08X %08X\n', *ITM_TCR, *ITM_TER

, *SCB_DEMCR, *SCB_DHCSR

);

if ((*SCB_DHCSR & 1) && (*ITM_TER & 1)) // Enabled?

Debug_ITMDebug = 1;

}

//****************************************************************************

[Katzenberger.Michael]

Posted on January 18, 2017 at 21:10

Thanks for pointing me into the right direction !

I have this for my SWV trace, suggest you look at ITM and SCB registers

(not Cortex-M0)

Unfortunately the target processor is a STM32F072 (Cortex M0) and the detection is not working.

The ARM documentation for Cortex M0 lists the DHCSR register:

http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.ddi0337e/CEGCJAHJ.html

 

but there is no detailed description about the bit definitions or the address of the register ...

Also the CMSIS register header file shows a lack of the CoreDebug_BASE register

Is this feature simply not available for a M0 device ???

[Tesla DeLorean]

Posted on January 18, 2017 at 21:33

>>

Is this feature simply not available for a M0 device ???

They dropped a lot of functionality out, which I've always felt is a step backward, which is why I don't have much time for the M0.

Look at the DBGMCU registers, and the clocks in the AHB/APB enabled at ResetHandler... because the debugger has likely tweaked things to suit its needs.