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CHAPTER 2 PIN FUNCTIONS
28
(2/2)
Symbol
Pin No.
I/O
I
I/O level
Function
EMPTY_B/
RCLAV
(Common
with RCIC
pin)
248
TTL
PHY Layer Buffer Empty/Receive Cell Available
The EMPTY_B/RCLAV signal indicates, to the
μ
PD98405,
that the receive FIFO of the PHY device contains no cell
data to be transferred and that the PHY device cannot
provide receive data. When the UTOPIA interface is in
octet-level handshaking mode, this pin functions as the
EMPTY_B pin. The EMPTY_B signal indicates that data on
Rx7 to Rx0 is invalid in the current clock cycle. In cell-level
handshaking mode, this pin functions as the RCLAV pin.
The RCLAV signal indicates that there are no more cells to
be transferred once the current cell has been transferred.
Connect a pull-down resistor when the EMPTY_B/RCLAV
pin is not used.
Receive Clock
The RCLK signal is a clock used to synchronize the
reception of cell data from the PHY layer device. Once the
system has been reset, the SAR system clock, input to the
SCLK pin, is output as is.
Transmit Data Bus
Tx7 to Tx0 is an 8-bit output bus used to transmit the
network traffic in byte form to the PHY layer device. The
eight bits are output to the PHY layer device in
synchronization with the rising edge of TCLK.
Transmit Start of Cell
The TSOC signal is output in synchronization with the first
byte of cell data to be transmitted.
Transmit Enable
The TENBL_B signal indicates to the PHY layer device that
Tx7 to Tx0 carries transmit data in the current clock cycle.
PHY Layer Buffer Full/Transmit Cell Available
The FULL_B signal indicates to the
μ
PD98405 that the input
buffer of the PHY device is full and cannot accept additional
data.
When the UTOPIA interface is in octet-level handshaking
mode, the PHY device makes this signal inactive when it
can receive cell data. In cell-level handshaking mode, this
pin functions as the TCLAV pin. The PHY device inputs the
signal to indicate that it can receive all the data in the next
cell, once the current cell has been transferred.
Connect a pull-up resistor when the FULL_B/TCLAV pin is
not used.
Transmit Clock
The TCLK signal is a clock used to synchronize the
transmission of cell data to the PHY layer device. The SAR
system clock, input to the SCLK pin, is output as is.
RCLK
244
O
TTL
Tx7-Tx0
255 - 258,
260 - 263
O
TTL
TSOC
250
O
TTL
TENBL_B
251
O
TTL
FULL_B/
TCLAV
(Common
with RCIT pin)
249
I
TTL
TCLK
253
O
TTL