STE400P STMicroelectronics, STE400P Datasheet - Page 20

• Manufacturer Part Number: STE400P
• Description: STE400P - 4 PORT 10-100 FAST ETHERNET TRANSCEIVER - PHY DATASHEET
• Manufacturer: STMicroelectronics

STE400P
Table 3. Register Descriptions
8.0 DEVICE OPERATION
The STE400P integrates the IEEE802.3u compliant functions of PCS(physical coding sub-layer), PMA(physical
medium attachment) sub-layer, and PMD(physical medium dependent) sub-layer for 100BASE-TX, and the
IEEE802.3 compliant functions of Manchester encoding/decoding and transceiver for 10BASE-T. All the func-
tions and operation schemes are described in the following sections.
8.1 100BASE-TX Transmit Operation
Regarding the 100BASE-TX transmission, the device provides the transmission functions of PCS, PMA, and
PMD for encoding of MII data nibbles to five-bit code-groups (4B/5B), scrambling, serialization of scrambled
code-groups, converting the serial NRZ code into NRZI code, converting the NRZI code into MLT3 code, and
then driving the MLT3 code into the category 5 Unshielded Twisted Pair cable through an isolation transformer
with the turns ratio of 1: 1.
20/34
3
2~1
0
SC = Self Clear
Bit #
Data code-groups Encoder: In normal MII mode application, the device receives nibble type 4B data via
the TxD0~3 inputs of the MII. These inputs are sampled by the device on the rising edge of Tx-clk and
passed to the 4B/5B encoder to generate the 5B code-group used by 100BASE-TX.
Idle code-groups: In order to establish and maintain the clock synchronization, the device needs to keep
transmitting signals to the medium. The device will generate Idle code-groups for transmission when there
is no real data want to be sent by MAC.
Start-of-Stream Delimiter-SSD (/J/K/): In a transmission stream, the first 16 nibbles are MAC preamble.
In order to let partner delineate the boundary of a data transmission sequence and to authenticate carrier
events, the device will replace the first 2 nibbles of the MAC preamble with /J/K/ code-groups.
End-of-Stream Delimiter-ESD (/T/R/): In order to indicate the termination of the normal data transmis-
sions, the device will insert 2 nibbles of /T/R/ code-group after the last nibble of FCS.
Scrambling: All the encoded data(including the idle, SSD, and ESD code-groups) is passed to the data
scrambler to reduce the EMI and spread the power spectrum using a 10-bit scrambler seed loaded at the
beginning.
Data conversion of Parallel to Serial, NRZ to NRZI, NRZI to MLT3: After scrambled, the transmission
data with 5B type in 25MHz will be converted to serial bit stream in 125MHz by the parallel to serial func-
tion. After serialized, the transmission serial bit stream will be further converted from NRZ to NRZI format.
This NRZI conversion function can be bypassed, if the bit 7 of PR19 register is cleared as 0. After NRZI
converted, the NRZI bit stream is passed through MLT3 encoder to generate the TP-PMD specified MLT3
code. With this MLT3 code, it lowers the frequency and reduces the energy of the transmission signal in
the UTP cable and also makes the system easily to meet the FCC specification of EMI.
Wave-Shaper and Media Signal Driver: In order to reduce the energy of the harmonic frequency of trans-
mission signals, the device provides the wave-shaper prior to the line driver to smooth but keep symmetric
the rising/falling edge of transmission signals. The wave-shaped signals include the 100BASE-TX and
10BASE-T both are passed to the same media signal driver. This design can simplify the external magnetic
Reserved
RXER C
Name
SI
1=Super Isolate Mode
0=Normal Operation
Write as “00”; Ignore when Read
1=Enable RXER Code Mode
0=Disable RXER Code Mode
Descriptions
Default Val
00
0
0
RW Type
R/W
R/W
R/W