TDO

Boundary Scan Data Output Pad

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

figures/x3899n.gif

The TDO data output pad is connected to the boundary scan TDO output. It is connected to the external circuit to provide the boundary scan data for each Low-to-High TCK transition. The function of the TDO pad is device configuration dependent and can be used as follows.

During configuration, TDO is connected to the boundary scan logic.
After configuration, if boundary scan is not used, the TDO pad can be used as a bidirectional 3-state I/O pad by the routing tool.
After configuration, if boundary scan is used, the TDO pad is still used as an output from the boundary scan logic.