DS3181/DS3182/DS3183/DS3184
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10.6 UTOPIA/POS-PHY/SPI-3 System Interface
10.6.1 General Description
The UTOPIA/POS-PHY system interface transports ATM cells or HDLC packets between the DS318x and an ATM
or Link Layer device. In UTOPIA mode, the DS318x is connected to an ATM layer device and cells are transported
via a UTOPIA L2 or UTOPIA L3 Bus. In POS-PHY packet mode, the DS318x is connected to a Link Layer device
and the packets are transported via a POS-PHY 2 or a POS-PHY 3 (or SPI-3) Bus. In POS-PHY cell mode, the
DS318x is connected to an ATM layer device and cells are transported via a POS-PHY 2 or a POS-PHY 3 (or SPI-
3) Bus. The system interface supports 8-bit, 16-bit, or 32-bit transfers at a rate of 66MHz or less.
The receive direction removes cell/packet data for each port from the FIFO, and outputs the cell/packet data to the
ATM/Link Layer device via the system interface.
The transmit direction inputs the cell/packet data from the ATM/Link Layer device via the system interface, and
stores the cell/packet data for each port in the FIFO.
See
Figure 10-20 for the location of the system interface block in the DS318x devices.
Figure 10-20. System Interface Functional Diagram
DS3/E3
Transmit
LIU
IEEE P1149.1
JTAG Test
Access Port
Microprocessor
Interface
HDLC
FEAC
LLB
DL
B
DS3 / E3
Transmit
Formatter
DS3 / E3
Receive
Framer
Trail
Trace
Buffer
Tx Cell
Processor
Tx
FIFO
Sy
st
em
Int
er
fac
e
Rx Cell
Processor
Rx
FIFO
Tx Packet
Processor
SL
B
Rx Packet
Processor
DS3/E3
Receive
LIU
TAIS
TUA1
TX FRAC/
PLCP
RX FRAC/
PLCP
Clock Rate
Adapter
TX BERT
RX BERT
PL
B
AL
B
UA1
GEN
B3ZS/
HDB3
Encoder
B3ZS/
HDB3
Decoder
10.6.2 Features
Programmable system interface type – When performing cell mapping/demapping, the system interface can
be programmed as a UTOPIA Level 2 Bus, a UTOPIA Level 3 Bus, a POS-PHY Level 2 Bus, or a POS-PHY
Level 3 (or SPI-3) Bus. When performing packet mapping/demapping, the system interface can be
programmed as a POS-PHY Level 2 Bus or a POS-PHY Level 3 (or SPI-3) Bus.
Selectable system interface bus width – The data bus can be a 32-bit, 16-bit, or 8-bit bus at operations
speeds up to 66 MHz.
Supports multiple ports on the system interface – Each line has its own port address for access via the
system interface.
Supports per-port system loopback – Each port can be placed in system loopback which causes
cells/packets from the transmit FIFO to be looped back to the receive FIFO.
System interface byte reordering – In 16-bit and 32-bit modes, the received/transmitted order of the bytes
transferred across the system interface is programmable. i.e., the first byte received/transmitted by ATM cell /
packet processing can be transferred in [31:24] ([15:8]) or [7:0].