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CHAPTER 4 INTERFACES
100
The
μ
PD98405 does not support multi PHY (UTOPIA Level 2). Therefore, do not place any signals in the
high impedance state.
The UTOPIA interface consists of a clock signal bus for each of transmission and reception supplied by the
μ
PD98405, an 8-bit data signal bus, and three control signal buses.
TCLK (output)
:
Transmit clock. The SAR system clock, input to the SCLK pin, is output as is.
TENBL_B (output)
:
Transmit enable signal. The TENBL_B signal notifies the PHY device that Tx7
through Tx0 carry transmit data in the current clock cycle.
FULL_B/TCLAV (input)
:
The function of this pin differs between the octet-level and cell-level
handshaking modes. In octet-level handshaking mode, this pin functions as the
FULL_B pin to notify the
μ
PD98405 that the PHY device can receive no more
data because the buffer is full. In cell-level handshaking mode, this pin
functions as the TCLAV pin to notify the
μ
PD98405 whether the next cell can be
received.
Tx7-Tx0 (output)
:
Transmit data bus
TSOC (output)
:
Transmit cell start signal. The TSOC signal is output in synchronization with the
first byte of the transmit cell data.
RCLK (output)
:
Receive clock. The SAR system clock, input to the SCLK pin, is output as is.
RENBL_B (output)
:
Receive enable signal. The RENBL_B signal notifies the PHY device that the
μ
PD98405 is ready to accept data in the next clock cycle.
EMPTY_B/RCLAV (input)
: The function of this pin differs between the octet-level and cell-level
handshaking modes. In octet-level handshaking mode, this pin functions as the
EMPTY_B pin and is used by the PHY device to notify the
μ
PD98405 that the
data on Rx7 through Rx0 is invalid because there is no receive data to be
provided. In cell-level handshaking mode, this pin functions as the RCLAV pin
to indicate whether subsequent cell data exists.
Rx7-Rx0 (input)
:
Receive data bus
RSOC (input)
:
Receive cell start signal. The RSOC signal is input in synchronization with the
first byte of the cell data received from the PHY device.
When this interface is not used, leave these pins open. The input pins are connected to internal pull-down
resistors.