How to make a JTAG debugger

[Jeff Cours]

Hi everyone,

I've been curious about what it would take to create a JTAG debugger for ARM chips. Does anyone have any pointers to the specs that cover what signalling the debugger would need to send to the target chip?

Thanks very much in advance,

Jeff

[D. P.Seidenspinner]

Hi Jeff,

 

I think this is a good question. I’ve wondered about this one, too.

The Industry seems to be headed towards J-Link. At least that’s what I see on the new Dev. boards.

 

Let’s have others chime in here to check their pulse.

Best regards,

Don

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[David Neiss]

There is an open source JTAG debugger project http://sourceforge.net/projects/openocd/

[Jeff Cours]

Thanks very much for the pointer! There's a JTAG primer off their documentation site that's a good starting point. I also found the ARM Debug Interface Architecture Specification ADIv5.0 to ADIv5.2 Architecture specification on the ARM site and am looking at it now.

Jeff

[Kurt Jensen]

I played around with openOCD and Coocox on the STM32F4xx.  I think that openOCD has a few easy open
SWO/JTAG interface options - see http://openocd.sourceforge.net/doc/html/Debug-Adapter-Configuration.html#Debug-Adapter-Configuration

Since you can get cheap demo boards for almost any ARM platform with JTAG/SWO on board that can be broken out for use on your own boards, my enthusiasm for making my own has waned in recent years.

-Kurt