
ST70135A
20/29
Beware that an incorrect address configuration may lead to bus conflicts. A feature is defined to disable
(tri-state) all outputs of the Utopia interface. It is enabled by the TRI_STATE_EN bit in the Rx_interface
control register.
Pin Description Utopia 2 (Receive Interface)
*Active low signal
Pin Description Utopia 2 (Transmit interface)
*Active low signal
Name
Type
Meaning
Usage
Remark
RxClav
O
Receive Cell available
Signals to the ATM chip that
the STLC60135 has a cell
ready for transfer
Remains active for the entire
cell transfer
RxEnb*
I
Receive Enable
Signals to the physical layer
that the ATM chip will sample
and accept data during next
clock cycle
RxData and RxSOC could be
tri-state when RxEnb* is
inactive (high)
RxClk
I
Receive Byte Clock
Gives the timing signal for the
transfer, generated by ATM
layer chip.
RxData
O
Receive Data (8 bits)
ATM cell data, from physical
layer chip to ATM chip, byte
wide.
RxSOC
O
Receive Start Cell
Identifies the cell boundary on
RxData
Indicate to the ATM layer chip
that RxData contains the first
valid byte of a cell.
RxAddr
I
Receive Address (5 bits)
Use to select the port that will
be active or polled
RxRef *
O
Reference Clock
8kHz clock transported over
the network
Name
Type
Meaning
Usage
Remark
TxClav
O
Transmit Cell available
Signals tothe ATM chipthat the
physical layer chip is ready to
accept a cell
Remains active for the entire
cell transfer
TxEnb*
I
Transmit Enable
Signals to the physical layer
that TxData and TxSOCare
valid
TxClk
I
Transmit Byte Clock
Gives the timing signal for the
transfer, generated by ATM
layer chip.
TxData
I
Transmit Data (8 bits)
ATM cell data, to physical layer
chip to ATMchip, byte wide.
TxSOC
I
Transmit Start of Cell
Identifies the cell boundary on
TxData
TxAddr
I
Transmit Address (5 bits)
Use to select the port that will
be active or polled
TxRef *
I
Reference Clock
8kHz clock from the ATM layer
chip