TCK

Boundary Scan Test Clock Input Pad

XC3000	XC4000E	XC4000X	XC5200	XC9000	Spartan	SpartanXL	Virtex
N/A	Primitive	Primitive	Primitive	N/A	Primitive	Primitive	N/A

figures/x3895n.gif

The TCK input pad is connected to the boundary scan test clock, which shifts the serial data and instructions into and out of the boundary scan data registers. The function of the TCK pad is device configuration dependent and can be used as follows.

During configuration TCK is connected to the boundary scan logic.
After configuration, if boundary scan is not used, the TCK pad is unrestricted and can be used by the routing tool as an input/output pad.
After configuration, if boundary scan is used, the TCK pad can be used for user-logic input by connecting it directly to the user logic.