Dear sirs,
The ARM v7ar manual says that DCC data registers DBGDTRTX and DBGDTRRX have RW attributes from external view.
It confuses me why DBGDTRTX can be written from external debugger. what is the purpose for this function?
The same confusion to DBGDTRRX why it can be read from external debugger?
Can any expert explain it to me? Thanks.
cray
Yes, that is correct. ARMv7-M has a different style of architecture where the processor is completely halted in Debug state. The DCRDR and DCRSR are used to access the processor registers: everything else is memory mapped and can be directly accessed via the DAP. Contrast this with the "A" profile processors which have coprocessors and multiple exception levels with Banked registers, and you can see why these architectures take different approaches.