
34
x r
PRELIMINARY
E3 UNI FOR ATM
XRT7234
REV. P1.0.0
146
TxAddr4
I
Transmit Utopia Address Bus—MSB Input:
This input pin, along with
TxAddr3 through TxAddr0 comprise the Transmit Utopia Address Bus
input pins. The Transmit Utopia Address Bus is only in use when the UNI
is operating in the M-PHY mode. When the ATM Layer processor wishes
to write data to a particular UNI device, it will provide the address of the
“intended UNI” on the Transmit Utopia Address Bus. The contents of the
Transmit Utopia Address Bus input pins are sampled on the rising edge
of TxClk. The E3 UNI will compare the data on the Transmit Utopia
Address Bus input pins with the pre-programmed contents of the TxUT
Address Register (Address = 82h). If these two values are identical and if
the TxENB pin is asserted, then the TxClav output pin will be driven to
the appropriate state (based upon the TxFIFO fill level) for the Cell Level
handshake mode of operation.
95
147
TxAddr0
I
Transmit Utopia Address Bus Input—LSB:
(See Description for TxAddr4)
148
TxAddr3
I
Transmit Utopia Address Bus input:
(See Description for TxAddr4)
96
149
TxAddr1
I
Transmit Utopia Address Bus input:
(See Description for TxAddr4)
150
TxAddr2
I
Transmit Utopia Address Bus input:
(See Description for TxAddr4)
97
151
TxClk
I
Transmit Utopia Interface Clock:
The Transmit Utopia Interface clock is
used to latch the data on the Transmit Utopia Data bus, into the Transmit
Utopia Interface block. This clock signal is also used as the timing source
for circuitry used to process the ATM cell data into and through the TxFIFO.
During Multi-PHY operation, the data on the Transmit Utopia Address
bus pins is also sampled on the rising edge of TxClk.
152
GND
***
Ground Signal Pin
98
153
GND
***
Ground Signal Pin
154
TxGFCMSB
O
Transmit GFC Nibble-Field Serial Input Port—MSB Indicator:
This
signal, along with TxGFC and TxGFCClk combine to function as the
“Transmit GFC Nibble Field” serial input port. This output signal will pulse
“high” when the MSB (most significant bit) of the GFC Nibble (for a given
valid cell) is expected at the TxGFC input pin.
Note:
The “Transmit GFC Nibble-field” serial input port only inserts the
GFC value into valid cells. Therefore, this output pin will only pulse “high”
when the Transmit Cell Processor is processing a “valid” cell. This output
pin will not pulse “high” when the Transmit Cell Processor is processing
Idle Cells.
99
155
ResetB
I
Reset Input:
When this “active-low” signal is asserted, the UNI device
will be asynchronously reset. Additionally, all outputs will be “tri-stated”,
and all on-chip register will be reset to their default values.
PIN DESCRIPTION (CONTINUED)
Pin
No.
100 Pin Package
Pin No. 160
PinPackage
Symbol
Type
Description