Lattice Semiconductor
ORCA ORSO82G5 Data Sheet
15
Figure 4. Top Level Overview, RX Path Logic, Single Channel
SERializer and DESerializer (SERDES)
Each SERDES block is a quad transceiver containing 4 channels for serial data transmission, with a per-channel
selectable data rate of 1.0—2.7 Gbits/s. Each SERDES block features high-speed CML interfaces and is designed
to operate in SONET backplane applications. The transceiver is controlled and congured via an 8-bit, 16-bit or 32-
bit MicroProcessor Interface through the FPGA. Each channel has dedicated registers that are readable and writ-
able. The device also contains global registers for control of common circuitry and functions. There are two SER-
DES blocks (or two quads), A and B, in the embedded portion of the device. Each quad supports four full duplex
serial links (Slice A contains channels AA, AB, AC, and AD while slice B contains channels BA, BB, BC, and BD).
Each SERDES block contains its own dedicated PLLs for transmit and receive clock generation. The user provides
a reference clock of the appropriate frequency (one per SERDES quad). The receiver PLLs extract the clock from
the serial input data and retime the data with the recovered clock. Clock divider circuitry also provides reference
clocks for the FPGA logic.
8:32 MUX and 32:8 DEMUX
The purpose of the MUX/DEMUX block is to provide a wide, low-speed interface at the FPGA portion of the
ORSO82G5 for each channel or data lane. The interface to the SERDES macro runs at 1/8th the bit rate of the data
lane. The MUX/DEMUX converts the data rate and bit-width so the FPGA core can run at 1/4th this frequency (i.e.,
1/32nd the SERDES rate). This gives a range of 31.25 MHz—84.38 MHz for the data crossing the FPGA/embed-
ded core boundary on SERDES only and SONET modes.
SONET Transmit OverHead (TOH) Processing, Framer and Scrambler/Descrambler (SONET and Cell
Modes)
In the transmit direction, the TOH block is responsible for processing the 144 (48 x 3) TOH bytes at the beginning of
each row of the transport frame. The TOH bytes may be transmitted transparently from the FPGA logic or may be
inserted by the TOH block (AUTO_TOH mode).
FPGA
Logic
Embedded Core
8:32
demux
Channel
Align,
(24x33)
FIFO
SONET
Framer
Decrambler
FPGA Data
SONET Processing
1.0-2.7Gbps
SERDES
8
LDOUT
RBC
1:8
dem
ux
8b
REFCLK
(155.52MHZ)
LEGEND:
RCK78x
x = A for Quad A, B for Quad B
RWCKxx
xx = [AA, AD] or [BA,BD]
IPCj_DOUT
j = [1,2]
SPE
Generator
Cell extractor,
RDXFIFO, IPC
SPE
DOUTxx_FP
DOUTxx[31:0]
32
FP
IPCj_DOUT
SYSCLK156x[1,2]
32
FP
From Other 3 Links
in Quad
77.76MHZ
RCK78x
RWCKxx
RSYSCLKx[1,2]