Content originally posted in LPCWare by wmues on Fri Aug 24 00:51:18 MST 2012
Using DMA via SPI for SD-cards is a very difficult thing.
For many SD-cards, you need to do bitwise shifting of incomming data for each response pattern and for each start of data block.
Due to the synchronous nature of the SD card SPI protocol, you will need CPU power for each response and for each start and end of a data block. So DMA will give NO better results than polling with the CPU.
Just my 2 cents.
