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Virtex™-II Platform FPGAs: Detailed Description
pull-ups during configuration. Other dedicated pins are
CCLK (the configuration clock pin), DONE, PROG_B, and
the boundary-scan pins: TDI, TDO, TMS, and TCK.
Depending on the configuration mode chosen, CCLK can
be an output generated by the FPGA, or an input accepting
an externally generated clock. The configuration pins and
loaded, the data for the next device in a daisy-chain is pre-
sented on the DOUT pin after the rising CCLK edge.
The interface is identical to slave serial except that an inter-
nal oscillator is used to generate the configuration clock
(CCLK). A wide range of frequencies can be selected for
CCLK which always starts at a slow default frequency. Con-
figuration bits then switch CCLK to a higher frequency for
the remainder of the configuration.
boundary scan pins are independent of the V
. The aux-
CCO
iliary power supply (V
) of 3.3V is used for these pins.
CCAUX
All configuration pins are LVTTL 12 mA. (See Virtex-II DC
Characteristics in Module 3.)
Slave SelectMAP Mode
The SelectMAP mode is the fastest configuration option.
Byte-wide data is written into the Virtex-II FPGA device with
a BUSY flag controlling the flow of data. An external data
source provides a byte stream, CCLK, an active Low Chip
Select (CS_B) signal and a Write signal (RDWR_B). If
BUSY is asserted (High) by the FPGA, the data must be
held until BUSY goes Low. Data can also be read using the
SelectMAP mode. If RDWR_B is asserted, configuration
data is read out of the FPGA as part of a readback opera-
tion.
A persist option is available which can be used to force the
configuration pins to retain their configuration function even
after device configuration is complete. If the persist option is
not selected then the configuration pins with the exception
of CCLK, PROG_B, and DONE can be used as user I/O in
normal operation. The persist option does not apply to the
boundary-scan related pins. The persist feature is valuable
in applications which employ partial reconfiguration or
reconfiguration on the fly.
Configuration Modes
Virtex-II supports the following five configuration modes:
After configuration, the pins of the SelectMAP port can be
used as additional user I/O. Alternatively, the port can be
retained to permit high-speed 8-bit readback using the per-
sist option.
•
•
•
•
•
Slave-serial mode
Master-serial mode
Multiple Virtex-II FPGAs can be configured using the
SelectMAP mode, and be made to start-up simultaneously.
To configure multiple devices in this way, wire the individual
CCLK, Data, RDWR_B, and BUSY pins of all the devices in
parallel. The individual devices are loaded separately by
deasserting the CS_B pin of each device in turn and writing
the appropriate data.
Slave SelectMAP mode
Master SelectMAP mode
Boundary-Scan mode (IEEE 1532/IEEE 1149)
A detailed description of configuration modes is provided in
the Virtex-II User Guide.
Slave-Serial Mode
Master SelectMAP Mode
In slave-serial mode, the FPGA receives configuration data
in bit-serial form from a serial PROM or other serial source
of configuration data. The CCLK pin on the FPGA is an
input in this mode. The serial bitstream must be setup at the
DIN input pin a short time before each rising edge of the
externally generated CCLK.
This mode is a master version of the SelectMAP mode. The
device is configured byte-wide on a CCLK supplied by the
Virtex-II FPGA device. Timing is similar to the Slave Serial-
MAP mode except that CCLK is supplied by the Virtex-II
FPGA.
Boundary-Scan (JTAG, IEEE 1532) Mode
Multiple FPGAs can be daisy-chained for configuration from
a single source. After a particular FPGA has been config-
ured, the data for the next device is routed internally to the
DOUT pin. The data on the DOUT pin changes on the rising
edge of CCLK.
In boundary-scan mode, dedicated pins are used for config-
uring the Virtex-II device. The configuration is done entirely
through the IEEE 1149.1 Test Access Port (TAP). Virtex-II
device configuration using Boundary scan is compliant with
IEEE 1149.1-1993 standard and the new IEEE 1532 stan-
dard for In-System Configurable (ISC) devices. The IEEE
1532 standard is backward compliant with the IEEE
1149.1-1993 TAP and state machine. The IEEE Standard
1532 for In-System Configurable (ISC) devices is intended
to be programmed, reprogrammed, or tested on the board
via a physical and logical protocol.
Slave-serial mode is selected by applying <111> to the
mode pins (M2, M1, M0). A weak pull-up on the mode pins
makes slave serial the default mode if the pins are left
unconnected.
Master-Serial Mode
In master-serial mode, the CCLK pin is an output pin. It is
the Virtex-II FPGA device that drives the configuration clock
on the CCLK pin to a Xilinx Serial PROM which in turn feeds
bit-serial data to the DIN input. The FPGA accepts this data
on each rising CCLK edge. After the FPGA has been
Configuration through the boundary-scan port is always
available, independent of the mode selection. Selecting the
boundary-scan mode simply turns off the other modes.
DS031-2 (v3.0) August 1, 2003
Product Specification
www.xilinx.com
1-800-255-7778
Module 2 of 4
37
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