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Invalid SWDIO in Keil MDK with CMSIS-DAP

Question asked by Kai Liu on Oct 10, 2014
Latest reply on Oct 14, 2014 by Kai Liu


I love to use on board debugger of FRDM to debug off-board microcontroller. Today I found an issue of WRONG SWDIO.


I used to MDK since it can be used to read chip IDCODE in debugger configuration Window. The target is M0+, MKL25Z. I have multiple boards. Some boards can be read as regular as:


SWDIO: 0x0BC11477 for MKL25Z128 (M0+)

SWDIO:0x2BA01477 for MK20DX128 (M4)



Some other boards will be read as:




Due to wrong IDCODE, MDK refuses to download.


I guess it is hardware related issue. Is there anything I can do? Shorter cable? Layout issue?