Multiple systems and JTAG

Technical discussions around xCORE processors (e.g. General Purpose (L/G), xCORE-USB, xCORE-Analog, xCORE-XA).
gaddra
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Multiple systems and JTAG

Post by gaddra »

I'm currently running two systems- each with 9 L1 processors. They are always run from the XDE.
I was wondering if it is possible to use these at the same time without two XTAG adapters. They both run the same code.
Since they are always booting from JTAG, is it possible to chain them and run it as if it is 1x 18 processor system?


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segher
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Post by segher »

In principle that should work. Two things though:
-- Look out for timing skew; if you end up having to run
your JTAG much slower, the startup / debug / etc. times
might become unbearable (startup will already be twice
slower, that is, if you do it in parallel on the old system);
-- I'm not sure the XTAG code can handle 18 nodes. Try
it and find out ;-)
srinie
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Post by srinie »

The two systems use JTAG scan chain, this should work
- how your L1's in each system are connected- Line?


Alternately, modifying the xn file to describe the two systems (second system boot source set to 'Link'), does this fit your requirement?
gaddra
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Post by gaddra »

Alright ,I'll give it a try today. Im running JTAG through a long rs232 cable so I have to use a JTAG divider of 4 (2 sometimes works) but its not too bad given there's not much debugging.

The two systems are not connected to each other in anyway, so I don't think I could set the second to boot from link via the first system.

When booting from JTAG, do the chained nodes still boot from the parent node, or is everything booted by JTAG?
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segher
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Post by segher »

Everything is "booted by JTAG" (if all your processors have
their boot MODE[2:3] set to "boot by JTAG").