topic lpc176x SPI-DMA SD-card access in LPC Microcontrollers

lpc176x SPI-DMA SD-card access

lpcware — Wed, 15 Jun 2016 17:28:01 GMT

Content originally posted in LPCWare by Dill on Wed Jun 20 05:01:27 MST 2012
Hello,

is it possible to access a SD-card via SPI using DMA on lpc1768?
Is there any example code available?

Thanks!

Re: lpc176x SPI-DMA SD-card access

lpcware — Wed, 15 Jun 2016 17:28:02 GMT

Content originally posted in LPCWare by solsal on Thu Aug 23 15:04:31 MST 2012
hi there

this is my question too:

is it possible to access a SD-card via SPI using DMA on lpc1768?
Is there any example code available?

regards

Re: lpc176x SPI-DMA SD-card access

lpcware — Wed, 15 Jun 2016 17:28:03 GMT

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.