STM32H7 - How to tell if debugger is attached?

[n2wx]

So I was handed code that breaks when debugging, but to fix the breakage breaks a power control on the board. Rev A only has this problem but Rev A is what I'm stuck with . Nice, right?

So I need a way to tell at run time whether the debugger is attached.

Does anyone have any idea how to accomplish this without changing the hardware?

[berendi]

Read GPIOA->IDR a few times, if bits 13/14 are changing, then there is most probably a debugger doing its stuff. Even EXTI interrupts should work on it while a pin is in AF mode.

[n2wx]

This sounds kind of contingent. How many reads do you think are needed for 99% (or some extremely reliable) confidence?

[berendi]

I would be extremely confident if I got 10 EXTI events within 1 ms on the SWCLK pin.

[Tesla DeLorean]

DBGMCU_IDC reads zero in Keil

[n2wx]

I was wondering why this sounded familiar. Our old friend for checking the chips release level! Unfortunately I'm in TrueStudio and I'm in an enforced timeout due to an overtemperature but when it comes back I'm going to see if I can persuade it to expose its J-Link-attached status. In a more perfect world I wouldn't have to ask you folks for workarounds for stupid problems like the one im facing.

[Pavel A.]

Have your debug start script write a magic value to some memory address at startup.

Then you'll know if the debugger is present.

This is simpler than poking around, though adds dependency on debugger script.

-- pa