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STE100P

7.0 DEVICE OPERATION

The STE100P 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.

7.1 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 1.414 : 1.

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 devicewill 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 tothe 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 mag-

netic connection with single one.

1

MFPSE

MF Preamble Suppression Enable

1 = Accept management frames with pre-amble suppressed.

0 = Do not accept management frames with preamble

suppressed.

This bit also controls the value of bit 6 in PR1 (MFPS).

1

R/W

0

---

reserved

0

RO

Table 4. Register Descriptions

Bit #

Name

Descriptions

Default Val

RW Type