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.

[Katzenberger.Michael]

Posted on January 18, 2017 at 22:42

A quick implementation does not appears to be quite easy. ...

In any case I'm very confused to find a chapter 32.6 Core debug in the

https://www.google.de/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&ved=0ahUKEwiztqPv08zRAhXqI8AKHc6hAgMQFggcMAA&url=http%3A%2F%2Fwww.st.com%2Fresource%2Fen%2Freference_manual%2Fdm00031936.pdf&usg=AFQjCNEVF1UlowviGuA1sKeAucu4yZIhtg&sig2=jT-iHieXtSPfHD7fhxT2qA&cad=rja

reference manual which are obviously not available:

[Tesla DeLorean]

Posted on January 19, 2017 at 04:24

I don't know, it is not going too be unduly hard to check a few things...

printf('%08X %08X %08X\n', RCC->AHBENR, RCC->APB1ENR, RCC->APB2ENR);

if (RCC->APB2ENR & RCC_APB2Periph_DBGMCU)  puts('DBGMCU Enabled');RCC->APB2ENR |= RCC_APB2Periph_DBGMCU; // Enable so with can readprintf('%08X %08X %08X\n', DBGMCU->CR, DBGMCU->APB1FZ, DBGMCU->APB2FZ);

[Andrew Neil]

Posted on December 13, 2017 at 18:42

katzenberger.michael wrote:

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

The feature exists - but the register is not accessible to the user code running in the chip.

>:(

See: