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Spartan and Spartan-XL FPGA Families Data Sheet
Figure 20 is a diagram of the Spartan/XL FPGA 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.
The other standard data register is the single flip-flop
BYPASS register. It synchronizes data being passed
through the FPGA to the next downstream boundary scan
device.
Spartan/XL devices can also be configured through the
boundary scan logic. See Configuration Through the
Boundary Scan Pins, page 37.
The FPGA provides two additional data registers that can
be specified using the BSCAN macro. The FPGA provides
two user pins (BSCAN.SEL1 and BSCAN.SEL2) which are
the decodes of two user instructions. For these instructions,
two corresponding pins (BSCAN.TDO1 and BSCAN.TDO2)
allow user scan data to be shifted out on TDO. The data
register clock (BSCAN.DRCK) is available for control of test
logic which the user may wish to implement with CLBs. The
NAND of TCK and RUN-TEST-IDLE is also provided
(BSCAN.IDLE).
Data Registers
The primary data register is the boundary scan register. For
each IOB pin in the FPGA, bonded or not, it includes three
bits for In, Out and 3-state Control. Non-IOB pins have
appropriate partial bit population for In or Out only. PRO-
GRAM, CCLK and DONE are not included in the boundary
scan register. Each EXTEST CAPTURE-DR state captures
all In, Out, and 3-state pins.
Instruction Set
The Spartan/XL FPGA boundary scan instruction set also
includes instructions to configure the device and read back
the configuration data. The instruction set is coded as
shown in Table 12.
The data register also includes the following non-pin bits:
TDO.T, and TDO.O, which are always bits 0 and 1 of the
data register, respectively, and BSCANT.UPD, which is
always the last bit of the data register. These three bound-
ary scan bits are special-purpose Xilinx test signals.
DS060 (v1.8) June 26, 2008
www.xilinx.com
21
Product Specification
XILINX [ XILINX, INC ]
