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Jtag Chain

Started by Hernan Dario Herrera August 4, 2004
Hi, everyone.
 
I have a three DSP system (DSP56303pv100), interconected via a Jtag Chain.
 
this is because I need to test the hardware conections on my system.
 
I know that to acces the second DSP in the chain, I have to bypass the first one.
the question is: when I have my first DSP bypassed, and I try to acces the second, is there any chance the 1st gets out of bypass mode?? and if it happends, how can I do to avoid that???
 
If anyone has worked with something similar, I appreciate any help dealing with JTAG chain, like steps or tricks, I don't know.
 
well, thanks. see you.
Hernan
 
 






When you use the ADS or GDS, the debugger will automatically do this for you. 
Down at the JTAG level, to talk to the data register of one device in your chain, you put the other 2 into bypass by shifting the BYPASS instruction into their instruction registers. The devices will stay in bypass until you perform another IR shift. Then they will do whatever instruction you shift in.

~Irene

 



Hernan Dario Herrera <h...@yahoo.com> wrote:
Hi, everyone.
 
I have a three DSP system (DSP56303pv100), interconected via a Jtag Chain.
 
this is because I need to test the hardware conections on my system.
 
I know that to acces the second DSP in the chain, I have to bypass the first one.
the question is: when I have my first DSP bypassed, and I try to acces the second, is there any chance the 1st gets out of bypass mode?? and if it happends, how can I do to avoid that???
 
If anyone has worked with something similar, I appreciate any help dealing with JTAG chain, like steps or tricks, I don't know.
 
well, thanks. see you.
Hernan
 
 





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Hi.
 
yes, it's at lowest jtag level.
 
But I still don't get one thing.
 
let's say that I put the 1st DSP in bypass mode. if I need to do a IDCODE (or a sample/test for example ) instruction on the second DSP, I have to perform another IR shift, IDCODE, and the 1st DSP gets out of the bypass mode. Am I right???
 
thanks


Irene Sierra <i...@yahoo.com> wrote:
When you use the ADS or GDS, the debugger will automatically do this for you. 
Down at the JTAG level, to talk to the data register of one device in your chain, you put the other 2 into bypass by shifting the BYPASS instruction into their instruction registers. The devices will stay in bypass until you perform another IR shift. Then they will do whatever instruction you shift in.

~Irene

 



Hernan Dario Herrera <h...@yahoo.com> wrote:
Hi, everyone.
 
I have a three DSP system (DSP56303pv100), interconected via a Jtag Chain.
 
this is because I need to test the hardware conections on my system.
 
I know that to acces the second DSP in the chain, I have to bypass the first one.
the question is: when I have my first DSP bypassed, and I try to acces the second, is there any chance the 1st gets out of bypass mode?? and if it happends, how can I do to avoid that???
 
If anyone has worked with something similar, I appreciate any help dealing with JTAG chain, like steps or tricks, I don't know.
 
well, thanks. see you.
Hernan
 
 





_____________________________________
Note: If you do a simple "reply" with your email client, only the author of this message will receive your answer.  You need to do a "reply all" if you want your answer to be distributed to the entire group.

_____________________________________
About this discussion group:

To Join:  m...@yahoogroups.com

To Post:  m...@yahoogroups.com

To Leave: m...@yahoogroups.com

Archives: http://www.yahoogroups.com/group/motoroladsp

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