Initial commit of SDIO example, initialization works
sdio: added readme
sdio: added read block method. DMA still does not work...
sdio: First working version, read of one block using DMA works
sdio: replaced spaces by tabs
sdio: make use of new helper functions
sdio: use new functions sdio_start_block_transfer/sdio_data_timeout
sdio: use new sdio_start_block_transfer interface, fix warnings
sdio: cleanup ACMD41 initialization with HCS flag
sdio: enabled interrupt on dma success
sdio: implemented timeout
sdio: use USART3 for output