Patent ID: 8214563
Filing Date: 2012-07-03
Classification: G06F,Y02D

Abstract:
1. A host controller comprising: a card slot into which a memory card is inserted; a transmission circuit that encodes transmission data, according to a serial transfer format; a reception circuit that decodes received data, according to the serial transfer format; a variable frequency clock generator that generates a transfer clock, and a card clock having a lower frequency than that of the transfer clock; a card clock output unit that outputs the card clock to the memory card; an interface unit comprising a transmission interface that transfers the transmission data from the transmission circuit to the memory card in synchronization with the transfer clock, and a reception interface that transfers received data from the memory card to the reception circuit in synchronization with the transfer clock; and a setting register circuit that holds setting information concerning an input/output method of the memory card, and controls frequencies of the transfer clock and the card clock generated by the variable frequency clock generator, based on the setting information, wherein the transmission interface comprises a first switch circuit including a plurality of selection units, each of the selection units sequentially selecting and outputting, in response to the transfer clock, first and second transmission data items from the transmission circuit; the reception interface comprises a second switch circuit including a plurality of selection units, each of the selection units of the reception interface sequentially selecting and outputting, in response to the transfer clock, first and second received data items from the memory card; and the transmission circuit encodes the transmission data in response to the card clock, and the reception circuit decodes the received data in response to the card clock.