R
Functional Description
Table 66: Slave Serial Mode Connections
Pin Name
FPGA Direction
Description
During Configuration
After Configuration
User I/O
HSWAP
Input
User I/O Pull-Up Control. When Drive at valid logic level
Low during configuration, enables throughout configuration.
pull-up resistors in all I/O pins to
respective I/O bank V
input.
CCO
0: Pull-up during configuration
1: No pull-ups
M[2:0]
Input
Mode Select. Selects the FPGA
configuration mode. See Design
Considerations for the HSWAP,
M[2:0], and VS[2:0] Pins.
M2 = 1, M1 = 1, M0 = 1 Sampled User I/O
when INIT_B goes High.
DIN
Input
Input
Data Input.
Serial data provided by host.
FPGA captures data on rising
CCLK edge.
User I/O
User I/O
CCLK
Configuration Clock. If CCLK
PCB trace is long or has multiple
connections, terminate this output
to maintain signal integrity. See
CCLK Design Considerations.
External clock.
INIT_B
Open-drain
Initialization Indicator. Active
Active during configuration. If
CRC error detected during
configuration, FPGA drives
INIT_B Low.
User I/O. If unused in the
application, drive INIT_B
High.
bidirectional I/O Low. Goes Low at start of
configuration during Initialization
memory clearing process.
Released at end of memory
clearing, when mode select pins
are sampled. In daisy-chain
applications, this signal requires
an external 4.7 kΩpull-up resistor
to VCCO_2.
DONE
Open-drain
FPGA Configuration Done. Low Low indicates that the FPGA is
Pulled High via external
pull-up. When High,
indicates that the FPGA
successfully configured.
bidirectional I/O during configuration. Goes High
when FPGA successfully
not yet configured.
completes configuration.
Requires external 330 Ω pull-up
resistor to 2.5V.
PROG_B
Input
Program FPGA. Active Low.
Must be High to allow
Drive PROG_B Low and
release to reprogram
FPGA.
When asserted Low for 500 ns or configuration to start.
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. Recommend
external 4.7 kΩ pull-up resistor to
2.5V. Internal pull-up value may
be weaker (see Table 78). If
driving externally with a 3.3V
output, use an open-drain or
open-collector driver or use a
current limiting series resistor.
100
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DS312-2 (v3.8) August 26, 2009
Product Specification
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