direction of JTAG signal TDI and TDO at PMC interface

[Mila]

Hallo professionals!
You have two boards: one is PMC mezzanine board and this board is placed at second (carrier board). You want use JTAG interface between this two boards.

Question is:
Is signal TDI input or output at carrier board?

At PCI and PMC standards I didn`t find explicit description of direction this signals.

Thank you very much for your help.

 

[FvM]

I can only imagine that PMC board JTAG interface is controlled from an external system (through the carrier board). Then the PMC board would have TDI (and also TCK and TMS) as input and TDO as output.

 

[ilikebbs]

TDI is input in any condition.

 

[Mila]

Thank you,
I have the same idea as FvM, but I need exact description at some standard and I can´t find this.

 

[sparso]

Can any one explain the JTAG timing or post some material with the timing explanation?

 

[synq]

be more specific on Jtag timing are u trying to run an external JTAG chain ?
are you trying to initiate a JTAG scan internally?
first one need a esternal JTAg controller in which you can set appropriate frrequency in the range 100Hz to all the way up to 2M provide you interconnect system has got some good noise imunity to scan clocks...
and the joke is in a lab don't dream anything better than 10Khz ..hahaha cruel isn't it?

 

[stanislavb]

Attached JTAG timing example:
TCK Fftck Frequency – 10MHz
TCK Ttckl Time low 50ns –
TCK Ttckh Time high 50ns –
TDI, TMS Ttsu Setup to TCK 40ns –
TDI, TMS Tth Hold from TCK 40ns –
TDO Ttval Valid from TCK – 30ns
TDO Ttz Hi-Z from TCK 5ns 40ns
Enjoy!