DM9010BI DAVICOM [Davicom Semiconductor, Inc.], DM9010BI Datasheet - Page 40

• Manufacturer Part Number: DM9010BI
• Description: Industrial-temperature 10/100 Mbps Single Chip Ethernet Controller With General Processor Interface
• Manufacturer: DAVICOM [Davicom Semiconductor, Inc.]

9. FUNCTIONAL DESCRIPTION
9.1 Host Interface
The host interface is the ISA BUS compatible mode.
There are eight IO bases, which are 300H, 310H,
320H, 330H, 340H, 350H, 360H, and 370H. The IO
base is latched from strap pins or loaded from the
EEPROM.
There are only two addressing ports through the
access of the host interface. One port is the INDEX
port and the other is the DATA port. The INDEX port is
decoded by the pin CMD =0 and the DATA port by the
pin CMD =1. The contents of the INDEX port are the
register address of the DATA port. Before the access
of any register, the address of the register must be
saved in the INDEX port.
9.2 Direct Memory Access Control
The DM9010BI provides DMA capability to simplify
the access of the internal memory. After the
programming of the starting address of the internal
memory and then issuing a dummy read/write
command to load the current data to internal data
buffer, the desired location of the internal memory can
be accessed by the read/write command registers.
The memory’s address will be increased with the size
that equals to the current operation mode (i.e. the
8-bit, 16-bit or 32-bit mode) and the data of the next
location will be loaded into internal data buffer
automatically. It is noted that the data of the first
access (the dummy read/write command) in a
sequential burst should be ignored because that the
data was the contents of the last read/write command.
The internal memory size is 16K bytes. The first
location of 3K bytes is used for the data buffer of the
packet transmission. The other 13K bytes are used for
the buffer of the receiving packets. So in the write
memory operation, when the bit 7 of IMR is set, the
memory address increment will wrap to location 0 if
the end of address (i.e. 3K) is reached. In a similar
way, in the read memory operation, when the bit 7 of
9.5 100Base-TX Operation
The block diagram in figure 3 provides an overview of
the functional blocks contained in the transmit section.
The transmitter section contains the following
Preliminary
Version: DM9010BI--DS-P01
January 12, 2010
Industrial-temperature Single Chip Ethernet Controller with General Processor Interface
IMR is set, the memory address increment will wrap to
location 0x0C00 if the end of address (i.e. 16K) is
reached.
9.3 Packet Transmission
There are two packets, sequentially named as index I
and index II, can be stored in the TX SRAM at the
same time. The index register 02h controls the
insertion of CRC and pads. Their statuses are
recorded at index registers 03h and 04h respectively.
The start address of transmission is 00h and the
current packet is index I after software or hardware
reset. Firstly write data to the TX SRAM using the
DMA port and then write the byte count to byte_ count
register at index register 0fch and 0fdh. Set the bit 1 of
control register. The DM9010BI starts to transmit the
index I packet. Before the transmission of the index I
packet ends, the data of the next (index II) packet can
be moved to TX SRAM. After the index I packet ends
the transmission, write the byte count data of the
index II to BYTE_COUNT register and then set the bit
1 of control register to transmit the index II packet.
The following packets, named index I, II, I, II, use the
same way to be transmitted.
9.4 Packet Reception
The RX SRAM is a ring data structure. The start
address of RX SRAM is 0C00h after software or
hardware reset. Each packet has a 4-byte header
followed with the data of the reception packet which
CRC field is included. The format of the 4-byte header
is 01h, status, BYTE_COUNT low, and
BYTE_COUNT high. It is noted that the start address
of each packet is in the proper address boundary
which depends on the operation mode (the 8-bit,
16-bit or 32-bit mode).
functional blocks:
- 4B5B Encoder
- Scrambler
- Parallel to Serial Converter
- NRZ to NRZI Converter
- NRZI to MLT-3
DM9010BI
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