#1楼主：RTL8201的datasheet的一些注释

文章发表于：2008-04-18 12:01

100Base-TX Transmit Function: The 100Base-TX transmit function is performed as follows: First the transmit data in 4 bit nibbles (TXD[3:0]), clocked in 25MHz (TXC) will be transformed into 5B symbol code, called 4B/5B encoding.
Scrambling, serializing and conversion to 125Mhz, and NRZ to NRZI will then take place. After this process, the NRZI signal will pass to the MLT3 encoder, then to the transmit line driver. The transmitter will first assert TXEN. Before transmitting the data pattern, it will send a /J/K/ symbol (Start-of-frame delimiter), the data symbol, and finally a /T/R/ symbol known as the End-Of-Frame delimiter. The 4B/5B and the scramble process can be bypassed by setting the PHY register. For better EMI performance consideration, the seed of the scrambler is related to the PHY address. Therefore in a hub/switch environment, every RTL8201BL will be set into a different PHY address so that they will use different scrambler seeds, which will spread the output of the MLT3 signals.

scramble：加扰

MLT3：多电平传输编码

NRZ：不归零码

NRZI：不归零反向编码

delimiter：定界符