
66 The Essential Guide to Serial ATA and SATA Express
Frames are preceded by primitives or scrambled Dwords. Scrambled Dwords are used to minimize
the impact of EMI created by repeating bit patterns on high-speed serial interfaces. By scrambling the
data, the encoded transmitted bit streams continuously change, therefore eliminating EMI issues. The
SATA protocol to enable this mode can be seen in Figure 2.21 by looking for the SATA_WTRM right
after the SATA_EOF.
The primitive is transmitted twice SATA_WRTM – SATA_WTRM.
They are immediately followed by SATA_CONT.
The transmitter transmits scrambled data Dwords using an industry standa ...