XMOS toolchain(XTAG+xSYS): effect of JTAG loop architecture?

[jerryXCORE]

After prototype developing with sliceKit, I finished design of my own board:
* I want to use XMOS tool chain for debugging.
--- so my board has a similar plug-chain-slot as seen on sliceKit
* My board has five components with JTAG capability, with loop architecture:
---JTAG loop: L16 + L16 + Component1 + Component2 + Component3

Here is the experiment:
* The whole JTAG loop is tested/verified with other boundary-scan tool(not from XMOS)
--- five components are found!
* But when I run "XRUN -l" on command-line, it founds no device.
* When I try to run a program from xTimeComposer, it can't connect to the device.

And here is my question:
* If I want to use XMOS tool chain, do I need to use JTAG loop with 'L16' only?
-- For example, with JTAG loop: L16 + L16

Thanks!

[Joe]

Hi,

Your configuration should work as long as the instruction register length of the other (non XMOS) devices in your chain is 4 bits. If the IR in the other devices are not this length the debug will not work.

Due to this it's preferable to keep the XMOS devices on their own debug JTAG chain to ensure correct operation.

Regards,
Joe

[jerryXCORE]

Yeah, I double check my design, unfortunately: IR length of my other components is 5 bits.

How does the IR length matter? Shouldn't the XMOS-tool be smart enough to deal with it?

[henk]

Hi Jerry,

It is something that the tools could do, if one specced a full JTAG chain in the XN file. For example specify entries for non-XMOS taps with their IR length and ID code.

I think auto sensing may be quite hard if you don't know how many taps there are?

Cheers,
Henk

[jerryXCORE]

Hi, Henk:

That is a good news!

But how to specify those details in .xn file? I have checked .xn files under following directory, but can't figure out how to do it:
C:\Program Files (x86)\XMOS\xTIMEcomposer\Community_13.2.3\targets

Could you please provide a demo .xn file for including non-XMOS components in JATG chain?
Thanks!

Jerry

[henk]

Hi Jerry

What I meant is - the tools could be made to do it. It is not feasible with the 14 tools, hence you won't find anything in the documentation. But it is on the wish-list of features that would be useful.

Apologies for the misunderstanding,
Henk

[jerryXCORE]

Hi, Henk:

Yeah, I think it should be quite simple if IR length and codes of all components are provided in correct order.
Thanks for your explanation, and I put it on the wish-list too.

Jerry