CoreDebug->DEMCR default value

[Luke_abc]

Hi,

MCU - STM32H7

I have noticed that the CoreDebug_DEMCR_TRCENA bit in the DEMCR register is set by default if a debugger is connected. But, I need to enable it explicitly (as shown below) if the debugger is not connected.

    CoreDebug->DEMCR |= CoreDebug_DEMCR_TRCENA_Msk;

I want to use cyccnt and this is the reason why I want to enable this. Can I please ask why do we need to enable this explicitly if the debugger is not connected ? Also, Is the debugger enabling CoreDebug_DEMCR_TRCENA bit implicitly ?

[TDK]

> Can I please ask why do we need to enable this explicitly if the debugger is not connected ?
Because it's disabled by default.

> Also, Is the debugger enabling CoreDebug_DEMCR_TRCENA bit implicitly ?
Yes.

[Luke_abc]

Thank you for your reply. 

Can I please also ask if there are any disadvantages by keeping this DWT and ITM units enabled on a device on the field ?

[Tesla DeLorean]

Consumes some more power keeping the unit clocking, and having a 32-bit counter clock continously at CPU frequency. 

Debugger initialization turns on things it needs, settings it wants. ie DWT, FPB units etc, GPIO banks for PA and PB pins.

[TDK]

No disadvantages other than additional modest power consumption. Might interfere with putting it into sleep modes.

[Luke_abc]

Thank you @TDK  and @Tesla DeLorean  for your answers