9.13.15.2 Boundary Scan Registers - Enabled with Show BSR Details
Sets your I/O state to a specific output value during programming AND enables you to customize
the values for the Boundary Scan Register (Input, Output Enable, and Output). You can change
any Don't Care value in Boundary Scan Register States without changing the Output State of the
pin.
For example, if you want to Tri-State a pin during programming, set Output Enable to 0; the Don't
Care indicates that the other two values are immaterial. If you want a pin to drive a logic
High and have a logic 1 stored in the Input Boundary scan cell during programming, you may set
all the values to 1.
Table 9-20. BSR Details I/O Output Settings
Output State
Settings
Input
Output Enable
Output
Z (Tri-State)
Don't Care
0
Don't Care
0 (Low)
Don't Care
1
0
1 (High)
Don't Care
1
1
Last Known State
Last State
Last State
Last State
Table Key:
1 – High: I/Os are set to drive out logic
High.
0 – Low: I/Os are set to drive out logic
Low.
Don't Care : Don’t Care values have no impact on
the other settings.
Last_Known_State : Sampled value: I/Os are
set to the last value that was driven out prior to entering the programming mode, and then
held at that value during programming.
The following figure shows an example of Boundary Scan Register settings.Figure 9-134. Boundary Scan Registers
