Figure 8: JTAG Chain Block Diagram
FTDI
USB
JTAG
(U8)
TCK
TMS
TDI
TDO
JTAG
2 mm
Conn.
(J4)
TDO
TDI
TMS
TCK
Level-shift
FPGA
Level-shift
1.8V
3.3V
TCK
TMS
TDI
TDO
1.8V
3.3V
U50
U1
U75
FMC+
HSPC
Connector
TMS
TCK
TDO
TDI
SPST Bus Switch
U72
J18
N.C.
X21649-110618
FMCP Connector JTAG Bypass
When an FMC is attached to the VCU128 board FMC+ HSPC connector J18, it is automatically
added to the JTAG chain through the electronically controlled single-pole single-throw (SPST)
switch U72. The SPST switch is in a normally closed state and transitions to an open state when
the FMC is attached. Switch U72 adds an attached FMC to the FPGA JTAG chain as determined
by the
FMCP_HSPC_PRSNT_M2C_B
signal.
IMPORTANT! The attached FMC must implement a TDI-to-TDO connection through a device or bypass
jumper to ensure that the JTAG chain connects to the FPGA U1.
The JTAG connectivity on the VCU128 board allows a host computer to download bitstreams to
the FPGA using the Xilinx tools. In addition, the JTAG connector allows debug tools such as the
Vivado
®
serial I/O analyzer or a software debugger to access the FPGA. The Xilinx tools can also
program the Quad SPI flash memory.
Chapter 3: Board Component Descriptions
UG1302 (v1.1) April 21, 2021
VCU128 Board User Guide
36