Answers Database

XC9500: What should be done with unused JTAG pins in the XC9500?


Record #1408

Product Family:  Hardware

Product Line:  9500

Problem Title:
XC9500: What should be done with unused JTAG pins in the XC9500?


Problem Description:
Keywords: JTAG, 9500, unused pins

Urgency: standard

General Description:

Can the Unused JTAG pins of a 9500 device be left unconnected?




Solution 1:

When using the TAP, users must make sure that they do not inadvertantly
move out of the test-logic-reset state.

At a minimum, the user should pull TCK high or TCK low.  What matters is
not to move the TAP out of the test-logic-reset state.	Since TCK advances
the TAP state machine, any inputs on TDI or TMS will not have any effect,
if TCK is fixed.

TDO, as defined by the IEEE 1149.1 spec, is an output with a pullup.  No
external circuitry needs to be connected to the TDO pin.



End of Record #1408