Bus Interface and Clock Frequency Control Method of Bus Interface

A bus interface electrically connected to a first device, wherein the bus interface comprises:

• a chip select terminal for transmitting a chip select signal to start data transmission;
• a first transmission bus terminal for sending data to a second device when the data transmission starts;
• a second transmission bus terminal for sending the data from the second device to the first device when the data transmission starts;
• and
• a clock control device, comprising:
• a frequency processing unit for generating a frequency control bit which adjusts the frequency of a transmission clock;
• and
• a transmission clock generating unit for receiving the frequency control bit and generating a transmission clock in accordance with the frequency control bit.

A clock frequency control method for adjusting a frequency of a transmission clock employed by a bus interface, comprising:

• determining whether a bus has started to transmit at least one command or at least one data;
• detecting whether a frequency setting value is changed when the bus starts to transmit the command or the data;
• detecting whether transmission of a packet group is finished when the frequency setting value has been changed;
• loading the frequency setting value which has been changed and adjusting the frequency of the transmission clock according to the frequency setting value which has been loaded;
• and
• outputting the transmission clock with a frequency which has been adjusted.

A clock frequency control method for adjusting a frequency of a transmission clock employed by a bus interface during packet group transmission, the method comprising:

• determining whether a bus has started to transmit at least one command or at least one data;
• detecting whether a variable output timing signal is asserted when the bus starts to transmit the command or the data;
• selecting one from a plurality of frequency setting values according to a frequency control bit;
• and
• adjusting the frequency of the transmission clock according to the frequency setting value which has been selected.