Patent ID: 7698469

Claim:
A serial transmission controller for transmitting an access command corresponding to an access address to a serial interface, the serial transmission controller comprising: a current address register, for saving a current address; an address encoder, coupled to the current address register, for comparing the current address and the access address, and selecting an access address mode from a plurality of transmission address modes and producing address information correspondingly; a serial interface encoder, coupled to the address encoder, for transmitting the access command and the address information to the serial interface by serial transmission; and a variable length encoder, for encoding the access command to different length of bits, and transmitting the encoded access command through the serial interface encoder to the serial interface, wherein the variable length encoder uses the transmission address modes according to a usage frequency statistics of the access commands such that the access command with higher frequency of usage is encoded with smaller length of bits; wherein the serial transmission controller selects the access command from a serial command set according to the access address mode, the serial command set comprises a plurality of command types, at least one of the command types can be used in the transmission address modes, and the transmission address modes use different bits to transmit the address information respectively.