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CHAPTER 3 FUNCTIONAL DESCRIPTION
User’s Manual S14054EJ4V0UM
27
3.2.2 PCS module
The PCS module implements the Physical Coding Sublayer function that is used to connect a 10 Mbps serial
interface. This module is connected to the MAC module at the system side. At the network side of the PCS module,
a PHY device supporting MII or 10BASE-T transceiver can be connected.
If the PCS module is set so that it connects an MII-supporting PHY device as the external device at the network
side, the PCS module connects the MII signal from the MAC module to the external device as is. If the PCS module
is set so that it is connected to an external device with the 10 Mbps serial bus interface, the module converts MII
nibble data into serial data. In this way, the PCS module can be used to configure a 10/100BASE-TX system via MII,
and a 10BASE-T system with the 10M-bps serial interface.
3.2.3 SAL (Station Address Logic) module
The SAL module detects the value in the destination address field of a receive packet, compares the address
under conditions specified in advance, and reports the result of the comparison to the receive FIFO. The receive
FIFO accepts or rejects the receive packet, depending on an address condition, in accordance with the report from
the SAL module.
The address condition can be set for each port or by address type.
A unicast address is compared with the value of the station address register that is set in the control register of
each port. In the case of a multicast address, whether all multicast packets are received or only the multicast packet
selected by a hash table is received can be selected. As for a broadcast address, whether the broadcast packet is
received or not can be selected.
In addition, the
µ
PD98431 can also accept all packets for all address types. For address filtering conditions, refer
to
3.5.5 Address filtering
.
3.2.4 STAT (STATistics counter) module
The
µ
PD98431 has a statistics counter set that is useful for implementing RMON/SMNP, for each port. The STAT
module implements this statistics counter set. For details of the statistics counter, refer to
3.12 Statistics Counter
.
3.2.5 Internal FIFOs
As FIFOs, the
µ
PD98431 has a high-speed dual-port SRAM which has a capacity of 2K bytes for reception and
512 bytes for transmission for each port. The FIFOs also arbitrate the transmit/receive clock from the network side
and FIFO bus clock from the system side.
3.2.6 FIFO bus module
The FIFO bus module interfaces between the internal FIFOs and upper layer. This interface has a speed of up to
66 MHz and a width of 64 bits. Two data bus modes can be selected: 64-bit single bus mode in which data can
transfer bidirectionally over a 64-bit bus, and 32-bit dual bus mode in which a 32-bit transmit data bus and a 32-bit
receive data bus, each of which transfers data unidirectionally, are used.
3.2.7 MII management module
The MII management module implements the MII serial management function standardized by IEEE802.3u. By
using this module, the
µ
PD98431 supplies one serial interface that is used to access PHY registers by using a MII
management frame between an external MII and PHY device.
3.2.8 Register bus module
The register bus module supplies control registers that are used to set each port or the entire chip, and a register
bus that is used to access the statistics counter of each port. The register bus consists of an 11-bit address bus and
a 32-bit bidirectional data bus. These general-purpose buses are not dependent on a specific CPU.
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