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Conflicting TCK Information

Question asked by mceleste on Nov 9, 2011
Latest reply on Nov 10, 2011 by DivyaS

The SHARC datasheet specifies that TCK must be asserted low after power-up for proper operation of the device on page 16.


On page 10 of EE-68, there is a note that "Previous versions of this document called for pull-up resistors on TMS, TCK, and TDI. The strong drive strength of the CMOS buffers used int he emulator make this unnecessary".


The other device in my JTAG chain (a Spartan 6) has internal pullups on TDI, TDO, TMS, and TCK.


These three things seem to conflict and I am wondering what the proper implementation is.


I am currently not using pullups or pulldowns on any signals except TRST, on which I have a 4.7K pulldown per EE-68 page 10.
What is the correct way to handle TCK?
Any help would be greatly appreciated. Please note I have read through other forum posts and did not see anything specific to this issue except a response stating that TCK (in addition to TDI and TMS) don't need pullups, but having them wouldn't hurt. This further conflicts with SHARC documentation.