For single-device configuration, the TAP
controller commands are issued automatically if the part is being configured with AMD configuration tools. The download cable must be attached to
the appropriate four JTAG pins (TMS, TCK,
TDI and TDO) to deliver the bitstream automatically from
the computer port to the FPGA. The tools automatically check for proper connections and drive
the commands to deliver and/or verify that the configuration bits are properly managed.
The following figure shows a typical JTAG
setup with the simple connections required to attach a single device to a JTAG signal header,
which can be driven from a processor, or an AMD programming
cable under control of the configuration tools. TCK is the
clock used for boundary-scan operations. The TDO - TDI connections create a serial datapath for shifting data through
the JTAG chain. TMS controls the transition between states in the TAP controller. Proper
physical connections of all of these signals are essential to JTAG functionality.
It is also possible to configure multiple devices in a chain, as shown in the following figure.