
Spartan-II FPGA Family: Functional Description
DS001-2 (v2.8) June 13, 2008
Module 2 of 4
Product Specification
15
R
Figure 9 is a diagram of the Spartan-II family boundary scan
logic. It includes three bits of Data Register per IOB, the
IEEE 1149.1 Test Access Port controller, and the Instruction
Register with decodes.
Bit Sequence
The bit sequence within each IOB is: In, Out, 3-State. The
input-only pins contribute only the In bit to the boundary
scan I/O data register, while the output-only pins
contributes all three bits.
From a cavity-up view of the chip (as shown in the FPGA
Editor), starting in the upper right chip corner, the boundary
scan data-register bits are ordered as shown in
Figure 10.BSDL (Boundary Scan Description Language) files for
Spartan-II family devices are available on the Xilinx
Figure 9: Spartan-II Family Boundary Scan Logic
D
Q
D
Q
IOB
M
U
X
Bypass
Register
IOB
TDO
TDI
IOB
1
0
1
0
1
0
1
0
1
0
sd
LE
DQ
D
Q
D
Q
1
0
1
0
1
0
1
0
DQ
LE
sd
LE
DQ
sd
LE
DQ
IOB
D
Q
1
0
DQ
LE
sd
IOB.T
DATA IN
IOB.I
IOB.Q
IOB.T
IOB.I
SHIFT/
CAPTURE
CLOCK DATA
REGISTER
DATAOUT
UPDATE
EXTEST
DS001_09_032300
Instruction Register