CY7C9689
4
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Pin Descriptions
Pin
Name
I/O Characteristics
Signal Description
Transmit Path Signals
68
TXCLK
TTL clock input
Internal Pull-Up
Transmit FIFO Clock.
Used to sample all Transmit FIFO and related interface signals.
44, 42,
40, 36,
34, 32,
30, 22
TXDATA[7:0]
TTL input, sampled on
TXCLK¦ or REFCLK¦
Internal Pull-Up
Parallel Transmit DATA Input.
When selected (CE=LOW and TXEN = asserted), information on these inputs
is processed as DATA when TXSC/D is LOW and ignored otherwise. When the
encoder is bypassed (ENCBYP is LOW), TXDATA[7:0] functions as the least
significant eight bits of the 10- or 12-bit pre-encoded transmit character.
When the Transmit FIFO is enabled (FIFOBYP is HIGH), these inputs are sam-
pled on the rising edge of TXCLK. When the Transmit FIFO is bypassed
(FIFOBYP is LOW) these inputs are captured on the rising edge of REFCLK.
54, 46 TXDATA[9:8]/
TXCMD[2:3]
TTL input, sampled on
TXCLK¦ or REFCLK¦
Internal Pull-Up
Parallel Transmit DATA or COMMAND Input.
When selected, BYTE8/10 is HIGH, and the encoder is enabled (ENCBYP is
HIGH), information on these inputs are processed as TXCMD[2:3] if TXSC/D is
HIGH and ignored otherwise.
When selected, BYTE8/10 is LOW, and the encoder is enabled (ENCBYP is
HIGH), information on these inputs are processed as TXDATA[9:8] if TXSC/D
is LOW and ignored otherwise.
When the encoder is bypassed (ENCBYP is LOW), TXDATA[9:8] functions as
the 9th and 10th bits of the 10- or 12-bit pre-encoded transmit character.
When the Transmit FIFO is enabled (FIFOBYP is HIGH), these inputs are sam-
pled on the rising edge of TXCLK. When the Transmit FIFO is bypassed
(FIFOBYP is LOW), these inputs are captured on the rising edge of REFCLK.
58, 56 TXCMD[1:0]
TTL input, sampled on
TXCLK¦ or REFCLK¦
Internal Pull-Up
Parallel Transmit COMMAND Input.
When selected and the encoder is enabled (ENCBYP is HIGH), information on
these inputs is processed as a COMMAND when TXSC/D is HIGH and ignored
otherwise.
When BYTE8/10 is HIGH and the encoder is bypassed (ENCBYP is LOW), the
TXCMD[1:0] inputs are ignored.
When BYTE8/10 is LOW and when the encoder is bypassed (ENCBYP is LOW),
the TXCMD[1:0] inputs function as the 11th and 12th (MSB) bits of the 12-bit
pre-encoded transmit character.
When the Transmit FIFO is enabled (FIFOBYP is HIGH), these inputs are sam-
pled on the rising edge of TXCLK. When the Transmit FIFO is bypassed
(FIFOBYP is LOW), these inputs are sampled on the rising edge of REFCLK.
20
TXSC/D
TTL input, sampled on
TXCLK¦ or REFCLK¦
Internal Pull-Up
COMMAND or DATA input selector.
When selected, BYTE8/10 is HIGH, and the encoder is enabled (ENCBYP is
HIGH), this input selects if the DATA or COMMAND inputs are processed. If
TXSC/D is HIGH, the value on TXCMD[3:0] is captured as one of sixteen pos-
sible COMMANDs, and the data on the TXDATA[7:0] bits are ignored. If TXSC/D
is LOW, the information on TXDATA[7:0] is captured as one of 256 possible 8-
bit DATA values, and the information on the TXCMD[3:0] bus is ignored.
When BYTE8/10 is LOW and the encoder is enabled (ENCBYP is HIGH) this
input selects if the DATA or COMMAND inputs are processed. If TXSC/D is
HIGH, the information on TXCMD[1:0] is captured as one of four possible COM-
MANDs, and the information on the TXDATA[9:0] bits are ignored. If TXSC/D is
LOW, the information on TXDATA[9:0] is captured as one of 1024 possible 10-
bit DATA values, and the information on the TXCMD[1:0] bus is ignored.
When the encoder is bypassed (ENCBYP is LOW) TXSC/D is ignored
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