CY7C9689
Pin Descriptions (continued)
Pin
Name
I/O Characteristics
Signal Description
31, 33 RXDATA[9:8]/ Three-state TTL out- Parallel Receive DATA or COMMAND Output.
RXCMD[2:3]
put, changes following
RXCLK¦
When BYTE8/10 is HIGH and the decoder is enabled (ENCBYP is HIGH) these
outputs reflects the value for the most recently received RXCMD[2:3].
When BYTE8/10 is LOW and the decoder is enabled (ENCBYP is HIGH) these
outputs reflects the value for the most recently received RXDATA[9:8].
When the decoder is bypassed (ENCBYP is LOW), RXDATA[9:8] functions as
the 9th and 10th bits of the 10- or 12-bit non-decoded receive character.
When the Receive FIFO is disabled (FIFOBYP is LOW), these outputs change
on the rising edge of the RXCLK output. When the Receive FIFO is enabled
(FIFOBYP is HIGH), these outputs change on the rising edge of the RXCLK
input.
RXEN is a three-state control for RXDATA[9:8]/RXCMD[2:3].
23, 29 RXCMD[1:0]
Three-state TTL out- Parallel Receive COMMAND Outputs.
put, changes following
When the decoder is enabled (ENCBYP is HIGH) these outputs reflect the value
RXCLK¦
for the most recently received RXCMD[1:0].
When BYTE8/10 is HIGH and the decoder is bypassed (ENCBYP is LOW),
these outputs have no meaning and are driven LOW.
When BYTE8/10 is LOW and the decoder is bypassed (ENCBYP is LOW),
RXCMD[1:0] functions as the 11th and 12th (MSB) bits of the 12-bit non-
decoded receive character.
When the Receive FIFO is disabled (FIFOBYP is LOW), this output changes on
the rising edge of the RXCLK output. When the Receive FIFO is enabled
(FIFOBYP is HIGH), these outputs change on the rising edge of the RXCLK
input.
RXEN is a three-state control for RXCMD[1:0].
Receive Enable Input.
69
RXEN
TTL input, sampled
on RXCLK¦
Internal Pull-Up
RXEN is a three-state control for the parallel data bus read operations. RXEN
is sampled on the rising edge of the RXCLK input (or output) and enables
parallel data bus read operations (when selected). The device is selected when
RXEN is asserted during an RXCLK cycle immediately following one in which
CE is sampled LOW. The parallel data pins are driven to active levels after the
rising edge of RXCLK. When RXEN is de-asserted (ending the selection) the
parallel data pins are High-Z after the rising edge of RXCLK.
Depending on the level on EXTFIFO, this signal can be active HIGH or active
LOW. If EXTFIFO is LOW, then RXEN is active LOW. If EXTFIFO is HIGH, then
RXEN is active HIGH. Data is delivered on the clock cycle following any clock
edge when RXEN is active.
65
RXSC/D
Three-state TTL out- COMMAND or DATA Output Indicator.
put, changes following
When BYTE8/10 is HIGH and the decoder is enabled (ENCBYP is HIGH), this
RXCLK¦
output indicates which group of outputs have been updated. If RXSC/D is HIGH,
RXCMD[3:0] contains a new COMMAND. The DATA on the RXDATA[7:0] pins
remain unchanged. If RXSC/D is LOW, RXDATA[7:0] contains a new DATA char-
acter. The COMMAND output on RXCMD[3:0] remain unchanged.
When BYTE8/10 is LOW and the decoder is enabled (ENCBYP is HIGH), this
output indicates which group of outputs have been updated. If RXSC/D is HIGH,
RXCMD[1:0] contains a new COMMAND and the DATA on the RXDATA[9:0]
remain unchanged. If RXSC/D is LOW, RXDATA[9:0] contains a new DATA char-
acter and the COMMAND output on RXCMD[1:0] remain unchanged.
When the decoder is bypassed (ENCBYP is LOW) RXSC/D is not used and
may be left unconnected.
RXEN is a three-state control for RXSC/D.
7
CYPRESS [ CYPRESS ]
