jtag board signals on P32A port Topic is solved

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jtag board signals on P32A port  Topic is solved

Postby Guest » Wed May 08, 2013 9:08 pm

Hello,
I've just started the project on U8A processor.
According to the dj reference design, there are 4 signals on the P32A port
(XL_UP1, XL_UP0, XL_DN0, XL_DN1) going to the JTAG board.
I don't have enough ports available for my project,
so I was going to use 32-bit port for chip enables and such.
I am afraid that my signals can interfere with port settings
for above above signals.

So what are the XL_UP1, XL_UP0, XL_DN0, XL_DN1 signals ?
Are they necessary ?

Thank you,
Gennady
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Ross
XCore Expert
Posts: 768
Joined: Thu Dec 10, 2009 9:20 pm

Postby Ross » Thu May 09, 2013 9:45 am

This link is used for "xScope" functionality, fast-printing etc. They are not a requirement, you can debug and program with JTAG alone if you are short on pins.
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Bianco
XCore Expert
Posts: 754
Joined: Thu Dec 10, 2009 6:56 pm

Postby Bianco » Thu May 09, 2013 12:02 pm

Multiple XMOS chips can be connected using external processor links called xConnect Links.
The four signals you mentioned are for a 2-wire (in each direction) xConnect Link (There also exists a 5-wire version that has a significant higher throughput). The most commonly used debug adapter is the XTAG-2, which also uses an XMOS chip. By connecting the target system with the debug adapter using the xConnect Link, you gain a high throughput debug link that can be used to send large amounts of data from the target system to the host computer. This is what the XMOS xScope functionality is about. If you don't use it, you can use the pins for other purposes, and if you do, the remaining pins on the 32 bit port should still be available for your own purposes.

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