Wooow cutting clock sounds cool... So that the Dsp cannot do any
further.. and to return to processing just agian feed the clock again
.. Very good way of break the process.. thats really totally hardware
interrupt...

Thanks Larwe...

larwe wrote:
> adonis wrote:
>
> > > "breakpoint in the software". Most processors with on-chip debug module
> > > support at least one or two hardware breakpoints, where a compare on
> > > the PC triggers the breakpoint in hardware.
> >
> > How does a hardware breakpoint work?.. How does it halts the processor.
>
> Architecture-specific. But they are normally designed to be completely
> invisible to the software; in other words, the h/w breakpoint will
> automatically cut the clock to the CPU and set a flag in an internal
> debugger register, which is then read out by the host PC over JTAG.

adonis wrote:

> > "breakpoint in the software". Most processors with on-chip debug module
> > support at least one or two hardware breakpoints, where a compare on
> > the PC triggers the breakpoint in hardware.
>
> How does a hardware breakpoint work?.. How does it halts the processor.

Architecture-specific. But they are normally designed to be completely
invisible to the software; in other words, the h/w breakpoint will
automatically cut the clock to the CPU and set a flag in an internal
debugger register, which is then read out by the host PC over JTAG.

larwe wrote:
> AK wrote:
>
> > you setup software breakpoint, instruction which is at given address is
> > replaced with instruction, which generates emulator exception.
>
> Yes, but this is really a "software breakpoint" as opposed to a
> "breakpoint in the software". Most processors with on-chip debug module
> support at least one or two hardware breakpoints, where a compare on
> the PC triggers the breakpoint in hardware.

How does a hardware breakpoint work?.. How does it halts the processor.
Is it that when some hardware line is pulled up or down, then some
software exception handler is called. What i actually mean to ask is,
whether it is purely hardware or is hardware just a trigger.

AK wrote:

> you setup software breakpoint, instruction which is at given address is
> replaced with instruction, which generates emulator exception.

Yes, but this is really a "software breakpoint" as opposed to a
"breakpoint in the software". Most processors with on-chip debug module
support at least one or two hardware breakpoints, where a compare on
the PC triggers the breakpoint in hardware.

Hey AK thanks for replying... I have certainly got to what i wanted to
know.

AK wrote:
> adonis wrote:
> > I have been using these JTAG emulators for ADSP blackfin processors for
> > quite some time now. I want to know about how the software breakpoint
> > actually works internally. I opened the ADSP JTAG emulator, it had a
> > BF531 DSP and a flash inside. Now, if my understanding is right... When
> > we run the code in emulator mode, then the code runs from the DSP in
> > the JTAG device.
> Not really, processor in JTAG device is only used for communication
> between PC and processor on board.
> >  Now when i keep a breakpoint in the emulator.. how does it work??.. I
> I am not sure how it is done exactly in blackfin, but generally, when
> you setup software breakpoint, instruction which is at given address is
> replaced with instruction, which generates emulator exception.
> Then processor goes to exception handling routines and talks to emulator
> 
> 
> Best Regards
> AK

adonis wrote:
> I have been using these JTAG emulators for ADSP blackfin processors for
> quite some time now. I want to know about how the software breakpoint
> actually works internally. I opened the ADSP JTAG emulator, it had a
> BF531 DSP and a flash inside. Now, if my understanding is right... When
> we run the code in emulator mode, then the code runs from the DSP in
> the JTAG device.
Not really, processor in JTAG device is only used for communication 
between PC and processor on board.
>  Now when i keep a breakpoint in the emulator.. how does it work??.. I
I am not sure how it is done exactly in blackfin, but generally, when 
you setup software breakpoint, instruction which is at given address is 
replaced with instruction, which generates emulator exception.
Then processor goes to exception handling routines and talks to emulator


Best Regards
AK

I have been using these JTAG emulators for ADSP blackfin processors for
quite some time now. I want to know about how the software breakpoint
actually works internally. I opened the ADSP JTAG emulator, it had a
BF531 DSP and a flash inside. Now, if my understanding is right... When
we run the code in emulator mode, then the code runs from the DSP in
the JTAG device.
 Now when i keep a breakpoint in the emulator.. how does it work??.. I
have one possible interpretation from my basic understanding.. please
help me understand if its right.... May be when we set the breakpoint,
the code from that part is pushed into some stack and some breakpoint
function is replaced onto that location. This function has some
infinite loop within....
Am i somewhere even close??