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Chapter 3:
Boundary-Scan and JTAG Configuration
Multiple Device Configuration
It is possible to configure multiple Virtex-4 devices in a chain. (See
in the JTAG chain are configured one at a time. The multiple device configuration steps can
be applied to any size chain.
Refer to the state diagram in
1.
2.
3.
4.
5.
6.
7.
All devices are active at this point.
Reconfiguring through Boundary-Scan
The ability of Virtex-4 devices to perform partial reconfiguration is the reason that the
configuration memory is not cleared when reconfiguring the device. When reconfiguring a
chain of devices, refer to
devices without possible internal contention. The first method is to pulse the
PROGRAM_B pin, resetting the internal configuration memory. The alternate method is to
perform a shutdown sequence, placing the device in a safe state. The following shutdown
sequence includes using internal registers. (For details on internal registers, refer to
Chapter
1.
2.
70
Figure 3-2
On power-up, place a logic 1 on the TMS and clock the TCK five times. This ensures
starting in the TLR (Test-Logic-Reset) state.
Load the CFG_IN instruction into the target device (and BYPASS in all other devices).
Go through the RTI state (RUN-TEST/IDLE).
Load in the configuration bitstream per
Repeat
step 2
and
step 3
for each device.
Reset all TAPs by clocking five 1s on TMS.
Load the JSTART command into all devices.
Go to the RTI state and clock TCK 12 times.
JTAG Header
TDO
Virtex-4
TDI
TDI
TMS
TMS
TCK
TCK
PROGRAM_B
Device 0
Figure 3-7: Boundary-Scan Chain of Devices
step 3
8)
Load the CFG_IN instruction.
In the SHIFT-DR state, load the synchronization word followed by the Reset CRC
Register (RCRC) command.
1111 1111 1111 1111 1111 1111 1111 1111→ Dummy word
1010 1010 1001 1001 0101 0101 0110 0110→ Synchronization word
0011 0000 0000 0000 1000 0000 0000 0001→ Header: Write to CMD register
0000 0000 0000 0000 0000 0000 0000 0111→ RCRC command
0000 0000 0000 0000 0000 0000 0000 0000→ flush pipe
www.xilinx.com
for the following TAP controller steps:
step 7
through
Virtex-4
FPGA
FPGA
TDO
TDI
TDO
TMS
TCK
PROGRAM_B
Device 1
in
Table
3-6. There are two methods to reconfigure Virtex-4
Virtex-4 FPGA Configuration User Guide
Figure
3-7.) The devices
step 11
in
Table
3-6.
Virtex-4
FPGA
TDI
TDO
TMS
TCK
PROGRAM_B
Device 2
ug071_36_073007
UG071 (v1.12) June 2, 2017
R
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