Method and apparatus of clock control associated with read latency for a card device

摘要

An SD memory card host controller supplies a clock to an SD memory card and issues a read command. After that, the host controller stops supplying the clock to the SD memory card during latency of read data from receipt of a response to the read command from the SD memory card to readout of data. The host controller resumes supplying the clock immediately before a data cycle starts. Power savings can thus be achieved by controlling the clock to be supplied to the SD memory card.