
XRT74L73
3 CHANNEL, ATM UNI/PPP DS3/E3 FRAMING CONTROLLER
REV. P1.0.1
PRELIMINARY
159
The following sections discuss each functional sub-
block of the Receive UTOPIA Interface block in detail.
Additionally, these sections discuss many of the fea-
tures associated with the Receive UTOPIA Interface
block as well as how these features can be optimized
to suit selected application needs. Detailed discus-
sion of Single-PHY and Multi-PHY operation will be
presented in its own section even though it involves
the use of all of these functional blocks.
3.4.2.1Receive UTOPIA Bus Output Interface
The Receive UTOPIA output interface complies with
the UTOPIA Level 2 standard interface (e.g., the
Receive UTOPIA can support both Single-PHY and
Multi-PHY operations). Additionally, the UNI provides
the option of varying the following features associated
with the Receive UTOPIA Bus interface.
Receive UTOPIA Data Bus width of 8 or 16 bits.
The cell size (e.g., the number of octets being processed
per cell via the UTOPIA bus)
A discussion of the operation of the Receive UTOPIA
Bus Interface along with each of these options will be
presented below.
3.4.2.1.1The Pins of the Receive UTOPIA Bus
Interface
The ATM Layer processor will interface to the Receive
UTOPIA Interface block via the following pins.
RxUData[15:0]—Receive UTOPIA Data Bus output
pins.
RxUAddr[4:0]—Receive UTOPIA Address Bus
input pins.
RxUClk—Receive UTOPIA Interface Block clock
input pin.
RxUSoC—Receive “Start of Cell” Indicator output
pin.
RxUPrty—Receive UTOPIA—Odd Parity output
pin.
RxUEn
—Receive UTOPIA Data Bus—Output
Enable input pin.
RxUClav/RxFullB*—RxFIFO Cell Available output
pin.
Each of these signals are discussed below.
F
IGURE
36. F
UNCTIONAL
B
LOCK
D
IAGRAM
OF
THE
R
ECEIVE
UTOPIA I
NTERFACE
B
LOCK
RxUtopia
Registers
D[15:0]
A[8:0]
Status Signals
Control Signals
Rx Utopia
Cell FIFO
RxUData [15:0]
RxUData [7:0]
RxUAddr [4:0]
RxUEn
RxUSoC
RxUClk
RxUtopia Interrupt
RxUClav
Controls from
Registers
RxFWrClk
RWrEn
(To Pin)
(To Interrupt block)
Read
Write
RxFData[7:0]
RxUData [7:0]/
RxUData [15:0]
RxUSoC
Status Bits to Registers
RxUPrty
To Pins
From RxCP