详细说明：sd卡的高速读写程序，sd模式（4数据线），是普通spi模式的约6倍，以及完全的sd卡的data sheet-sd card high speed read-write procedure, the sd pattern (4 data lines), are the ordinary spi pattern approximately 6 times, as well as complete sd card data sheet文件列表: sd_mem.c sd_mem.h SD_Simplified_Physical_Layer_Specification.pdf SD_Spec.pdf Simplified_SDIO_Card_Specification.pdf……