Debug through the JTAG.

[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.

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.

[igorpadykov · Accepted solution]

Hi Fabien

DAP provides commonly used jtag debug capabilities as, for example described on

ARM DS-5 Quick Start (i.MX6) - BlueWiki

Configuring jtag chains is described in Chapter 7 Configuring

JTAG Tools i.MX6 System Development User’s Guide

http://cache.freescale.com/files/32bit/doc/user_guide/IMX6DQ6SDLHDG.pdf

SDMA debug capacities though described in document, are not supported by nxp,

no tools are provided.

Best regards

igor

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[fmajeric]

Hi Igorpadykov,

Thank you for your response.

If I've well understood, It's only the DAP which manage the debug abilities of all externals tools that are connected through the JTAG pins. The OnCE capacities of the SDMA are never used from tools connected through the JTAG pins ?

As I'm concerned, I use a non-ARM debug tool. I mean, I use a JTAG debug tool not sell by ARM but compatible with the ARM IPs. When I want to halt and read a CPU register, I connect my JTAG debug tool to the JTAG pins.

Are the signals proceed in the chain like that ?

Please can you precise me the protocol followed by the signals when I want to read a CPU registers or fuses ?

Which controllers are concerned ? (Is my figure correct ?)

Thank you for your support,

Fabien.

[igorpadykov]

connections are given in i.MX6DQ Reference Manual p.4956

http://cache.nxp.com/files/soft_dev_tools/doc/support_info/iMX6DQPRM.pdf

protocol is JTAG IEEE1149.1 as described on that picture. For additional questions suggest to create new

thread.

~igor

[fmajeric]

Ok thank you.

You are right, I will create a new thread.

Fabien.