R
XC5200 Series Field Programmable Gate Arrays
Table 9: Pin Descriptions (Continued)
I/O
I/O
During
After
Pin Name
Config. Config.
Pin Description
If boundary scan is used, these pins are Test Data In, Test Clock, and Test Mode Select
inputs respectively. They come directly from the pads, bypassing the IOBs. These pins
can also be used as inputs to the CLB logic after configuration is completed.
If the BSCAN symbol is not placed in the design, all boundary scan functions are inhib-
ited once configuration is completed, and these pins become user-programmable I/O.
In this case, they must be called out by special schematic definitions. To use these pins,
place the library components TDI, TCK, and TMS instead of the usual pad symbols. In-
put or output buffers must still be used.
I/O
or I
(JTAG)
TDI, TCK,
TMS
I
High During Configuration (HDC) is driven High until the I/O go active. It is available as
a control output indicating that configuration is not yet completed. After configuration,
HDC is a user-programmable I/O pin.
HDC
LDC
O
O
I/O
I/O
Low During Configuration (LDC) is driven Low until the I/O go active. It is available as a
control output indicating that configuration is not yet completed. After configuration,
LDC is a user-programmable I/O pin.
Before and during configuration, INIT is a bidirectional signal. A 1 kΩ - 10 kΩ external
pull-up resistor is recommended.
As an active-Low open-drain output, INIT is held Low during the power stabilization and
internal clearing of the configuration memory. As an active-Low input, it can be used
to hold the FPGA in the internal WAIT state before the start of configuration. Master
mode devices stay in a WAIT state an additional 50 to 250 µs after INIT has gone High.
During configuration, a Low on this output indicates that a configuration data error has
occurred. After the I/O go active, INIT is a user-programmable I/O pin.
INIT
I/O
I/O
I or I/O
I/O
7
Four Global inputs each drive a dedicated internal global net with short delay and min-
imal skew. These internal global nets can also be driven from internal logic. If not used
to drive a global net, any of these pins is a user-programmable I/O pin.
The GCK1-GCK4 pins provide the shortest path to the four Global Buffers. Any input
pad symbol connected directly to the input of a BUFG symbol is automatically placed on
one of these pins.
GCK1 -
GCK4
Weak
Pull-up
These four inputs are used in Asynchronous Peripheral mode. The chip is selected
when CS0 is Low and CS1 is High. While the chip is selected, a Low on Write Strobe
(WS) loads the data present on the D0 - D7 inputs into the internal data buffer. A Low
on Read Strobe (RS) changes D7 into a status output — High if Ready, Low if Busy —
and drives D0 - D6 High.
CS0, CS1,
WS, RS
I
In Express mode, CS1 is used as a serial-enable signal for daisy-chaining.
WS and RS should be mutually exclusive, but if both are Low simultaneously, the Write
Strobe overrides. After configuration, these are user-programmable I/O pins.
During Master Parallel configuration, these 18 output pins address the configuration
EPROM. After configuration, they are user-programmable I/O pins.
A0 - A17
D0 - D7
O
I
I/O
I/O
During Master Parallel, Peripheral, and Express configuration, these eight input pins re-
ceive configuration data. After configuration, they are user-programmable I/O pins.
During Slave Serial or Master Serial configuration, DIN is the serial configuration data
input receiving data on the rising edge of CCLK. During Parallel configuration, DIN is
the D0 input. After configuration, DIN is a user-programmable I/O pin.
DIN
I
I/O
During configuration in any mode but Express mode, DOUT is the serial configuration
data output that can drive the DIN of daisy-chained slave FPGAs. DOUT data changes
on the falling edge of CCLK.
DOUT
O
I/O
In Express mode, DOUT is the status output that can drive the CS1 of daisy-chained
FPGAs, to enable and disable downstream devices.
After configuration, DOUT is a user-programmable I/O pin.
November 5, 1998 (Version 5.2)
7-103
ETC [ ETC ]
