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Debug through the JTAG.

Question asked by fmajeric on Apr 12, 2016
Latest reply on Apr 13, 2016 by fmajeric


Hello everybody,

 

I'm reading the i.MX 6Solo/6DualLite Applications Processor Reference Manual ( IMX6SDLRM, Rev. 1). What's a wonderful datasheet but little bit hard to catch all subtleties.

 

I'm interesting about the Debug abilities through the JTAG.

In Chapter 7 : System Debug, an overview is provided.

 

SJC.jpg

 

It is explained that through the JTAG protocol it is possible to stimulate the ARM DAP or the SDMA.

 

It seems the both can access and interact to specific modules:

  • The DAP enables debug access to the chip modules through APB-AP (the APB access port) and APB-Mux (the APB multiplexer).
  • The SDMA includes a OnCE controller which enables run/halt/single-step the core, access to the register/memory, etc...

 

So it seems, they has the same capacities and the section "55.4.13.2.3 Conflicts Between the JTAG and the ARM platform Accesses" confirm that.

 

>>So my questions are what is the difference between the DAP and the SDMA debug capacities ?

>>When should we use one or the other one ?

 

Thank you for any information.

 

Best Regards,

 

Fabien.

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