XC3S100E Xilinx Corp., XC3S100E Datasheet - Page 98

• Manufacturer Part Number: XC3S100E
• Description: Spartan-3e Fpga Family Complete Data Sheet
• Manufacturer: Xilinx Corp.

Functional Description
Table 64: Slave Parallel Mode Connections (Continued)
Voltage Compatibility
FPGA’s I/O Bank 2, supplied by the VCCO_2 supply input.
The VCCO_2 voltage can be 1.8V, 2.5V, or 3.3V to match
the requirements of the external host, ideally 2.5V. Using
1.8V or 3.3V requires additional design considerations as
the DONE and PROG_B pins are powered by the FPGA’s
2.5V V
tion of Spartan-3 FPGAs for additional information.
98
INIT_B
DONE
PROG_B
V
Pin Name
Most Slave Parallel interface signals are within the
CCAUX
supply. See XAPP453: The 3.3V Configura-
FPGA Direction
bidirectional I/O
bidirectional I/O
Open-drain
Open-drain
Input
Initialization Indicator. Active Low.
Goes Low at the start of
configuration during the Initialization
memory clearing process. Released
at the end of memory clearing, when
mode select pins are sampled. In
daisy-chain applications, this signal
requires an external 4.7 kΩ pull-up
resistor to VCCO_2.
FPGA Configuration Done. Low
during configuration. Goes High
when FPGA successfully completes
configuration. Requires external
330 Ω pull-up resistor to 2.5V.
Program FPGA. Active Low. When
asserted Low for 500 ns or longer,
forces the FPGA to restart its
configuration process by clearing
configuration memory and resetting
the DONE and INIT_B pins once
PROG_B returns High. Requires
external 4.7 kΩ pull-up resistor to
2.5V. If driving externally with a 3.3V
output, use an open-drain or
open-collector driver or use a
current limiting series resistor.
Description
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Daisy-Chaining
If the application requires multiple FPGAs with different con-
figurations, then configure the FPGAs using a daisy chain.
Use Slave Parallel mode (M[2:0] = <1:1:0>) for all FPGAs in
the daisy-chain. The schematic in
FPGA downloading and does not support the SelectMAP
read interface. The FPGA’s RDWR_B pin must be Low dur-
ing configuration.
After the lead FPGA is filled with its configuration data, the
lead FPGA enables the next FPGA in the daisy-chain by
asserting is chip-select output, CSO_B.
Active during configuration. If
CRC error detected during
configuration, FPGA drives
INIT_B Low.
Low indicates that the FPGA is
not yet configured.
Must be High to allow
configuration to start.
During Configuration
DS312-2 (v3.6) May 29, 2007
Figure 62
User I/O. If unused in the
application, drive INIT_B
High.
Pulled High via external
pull-up. When High,
indicates that the FPGA
successfully configured.
Drive PROG_B Low and
release to reprogram
FPGA.
After Configuration
Product Specification
is optimized for
R