
26
x r
PRELIMINARY
E3 UNI FOR ATM
XRT7234
REV. P1.0.0
49
76
RxClav
O
Receive Utopia—Cell Available:
The Receive Utopia Interface block
will assert this output pin in order to indicate that the Rx FIFO has some
ATM cell data that needs to be read by the ATM Layer Processor. The
exact functionality of this pin depends upon whether the UNI is operating
in the “Octet Level” or “Cell Level” handshake mode.
Octet Level Handshaking Mode:
When the Receive Utopia Interface
block is operating in the “octet-level handshaking” mode; this signal is
asserted (toggles “high”) when at least one byte of cell data exists within
the RxFIFO (within the Receive Utopia Interface block). This output pin
will toggle “l(fā)ow” when the RxFIFO is depleted of ATM cell data.
Cell Level Handshaking Mode:
When the Receive Utopia Interface
block is operating in the “cell-level handshaking” mode; this signal is
asserted if the RxFIFO contains at least one full cell of data. This signal
toggle “l(fā)ow” if the RxFIFO is depleted of data, or if it contains less than
one full cell of data.
Multi-PHY Operation:
When the UNI chip is operating in the Multi-PHY
mode, this signal will be tri-stated until the RxClk cycle following the
assertion of a valid address on the Receive Utopia Address bus input
pins (e.g., if the contents on the Receive Utopia Address bus pins match
that with the Receive Utopia Address Register). Afterwards, this output
pin will behave in accordance with the “cell-level handshaking” mode.
50
-
GND
****
Ground Signal Pin
77
RxAddr2
I
Receive Utopia Address Bus input:
(See Description for RxAddr4)
78
VDD
****
Power Supply Pin
51
79
RxAddr0
I
Receive Utopia Address Bus input—LSB:
(See Description for RxAddr4)
52
80
RxAddr1
I
Receive Utopia Address Bus input:
53
81
RxEnB*
I
Receive Utopia Interface—Output Enable:
This active-low input signal
is used to control the drivers of the Receive Utopia Data Bus. When this
signal is “high” (negated) then the Receive Utopia Data Bus is tri-stated.
When this signal is asserted, then the contents of the byte or word that is
at the “front of the RxFIFO” will be “popped” and placed on the Receive
Utopia Data bus on the very next rising edge of RxClk.
54
82
GND
****
Ground Signal Pin
55
83
GND
****
Ground Signal Pin
56
84
TDI
NC
Boundary Scan Pin:
Not Bonded out.
57
85
VDD
****
Power Supply Pin
PIN DESCRIPTION (CONTINUED)
Pin
No.
100 Pin Package
Pin No. 160
PinPackage
Symbol
Type
Description