CS4103 Datasheet, PDF (4/24 Pages) National Semiconductor (TI) – IEEE P1394a Physical Layer Device

Architectural Overview (Continued)
1.2 ARBITER
The Arbiter includes the logic to implement all of the state
machines described in clause 7, revision 2.0 of the P1394a
specification except for the Port State machine. These
include the state machines for bus reset, Tree-ID, Self-ID,
and normal arbitration. The Arbiter monitors the received
line states and controls the transmitted and repeated line
states for the various types of arbitration processes. The
Arbiter maintains the arbitration timer responsible for timing
the various gaps and line state lengths required for P1394a
operation. It also receives bus requests from the CS4210
via the Link Interface and sends the appropriate handshake
signals to indicate won/lost status to the Link Interface.
1.3 REGISTER SET
The Register Set implements all of the registers defined in
the P1394a specification. The Register Set has interfaces
to the Link Interface module for register reads and writes as
well as to the Packet Processor for register reads. The
Register Set also contains several National Semiconductor
specific register bits implemented in the address page
which are set aside for vendor specific registers and inter-
faces with the Arbiter and Port State. For example, the
Root hold-off bit affects the Arbiter and the Port Disabled
bits affect the operation of the Port State.
1.4 PACKET PROCESSOR
The Packet Processor decodes all PHY packets received
by the CS4103, (from both the CS4210 and cable inter-
faces) and generates all PHY response packets that the
CS4103 must send autonomously. The Packet Processor
also provides validity checking on PHY packets, discarding
invalid packets. During bus initialization and configuration,
the Packet Processor signals the reception of Self-ID pack-
ets to the Arbiter. The Arbiter uses this information during
the Self-ID process to increment the Node ID count.
1.5 PORT STATE
The Port State contains the Port Connection State Machine
described in clause 7.10.4, revision 2.0 of the P1394a
specification. The Port State keeps track of the connect
status and state of each port, (Disconnect, Resuming,
Active, etc.). The Port State also implements the connec-
tion timer used for timing various transitions within the state
machine and reports certain state conditions to other mod-
ules. For example, the Port State signals the Arbiter with
the Active, Resume, and Suspend state of each port along
with other status information. It also reports connection
change information for waking the CS4103 from a low-
power mode.
1.6 RECEIVER
The Receiver consists of the logic responsible for the data/
strobe decoding, the serial-to-parallel converter, and the
re-time FIFO. During packet reception and repeating, the
re-time FIFO buffers the data to allow for frequency differ-
ences between the transmitting and receiving PHYs. The
CS4103 writes data into the FIFO using the recovered
clock from the incoming data stream. It removes data from
the FIFO using the local system clock. The size of the FIFO
is calculated to allow the successful reception of a maxi-
mum length packet with a maximum clock offset between
this PHY and the Transmitter.
1.7 TRANSMITTER
The Transmitter handles the parallel-to-serial conversion
and data/strobe encoding operations. It can transmit data
from one of three sources: the Link Interface, the on-chip
Packet Processor, and the repeat path. The Arbiter controls
which path is selected for each transmit operation.
1.8 TRANSCEIVER
The Transceiver handles the interface to the 1394 cable. It
has drivers and receivers for the cable wires, (TPA+, TPA–,
TPB+, and TPB–). In addition, each Transceiver provides a
TpBias output for its port. On transmit, the Transceiver gen-
erates the appropriate speed signaling for 100, 200, and
400 Mbit/sec operation. The Transceiver also transmits 1,
0, and Z values on each differential pair (TPA and TPB).
The Receiver detects speed signaling values and the Arbi-
tration line states (1, 0, and Z). It contains separate differ-
ential receivers used to interpret data and strobe during
packet reception.
The Transceiver logic contains TpBias detection circuitry as
well as a Connect Detect circuit. The Transceiver enables
the Connect Detect circuit when the Port State logic
instructs the Transceiver to turn off the TpBias generation,
(for example, when the port enters the Suspend state).
1.9 PHASE-LOCKED LOOP (PLL)
The PLL module uses a 24.576 MHz crystal or clock input
to generate all of the local clocks. These include the 49.152
MHz system clock (SCLK) as well as the 98.304 MHz,
196.698 MHz, and 393.216 MHz clocks necessary for
transmitting at 100, 200, and 400 Mbit/sec. This PLL
design requires no external filter components.
1.10 RELATED DOCUMENTS
The following documents may be useful in understanding
the terms and concepts used in this publication.
• IEEE Standard 1394-1995 “IEEE Standard for a high
performance serial Bus”
• P1394a Draft 2.0 “P1394a Draft Standard for a High
Performance Serial Bus” (supplement)
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Revision 1.0