Lpc2000

> 
> If a FAT16/32 file system is implemented on this kit (using 
> something like RDCF or EFSL for example), how easy is it to swap the 
> flash cards between MMC and SD?  I've seen that SD and MMC can both 
> use the same transfer protocol to the uC, but does the change in 
> format also require an overhaul of the flash driver on the uC?
> 
> This is kind of a dual purpose question...  
> a) Can the same driver used for MMC cards be used for SD?
> b) if not, how different is the interface?
> 
> I'm not looking to be able to use both types of flash cards on the 
> same project...  more curious as which is the one to go with.
> 
> There certainly *seem* to be more examples out there for MMC than 
> SD...  In fact I haven't found any examples of SD file systems on 
> the LPC21xx range.  Maybe I'm just not looking hard enough?  :)
> 
> Any help would be greatly appreciated!
> 
> Cheers
> Darcy

Most of the implementations you will find for SD actually implement
the MMC single bit communication method rather than the 4 bit wide
mode of SD.  This is because the specification for SD is not open
to the public, and the implementation of it requires a yearly
royalty payment.  The MMC specification can be purchased, so there
has been more information available to developers.

I have used EFSL on SD, and it works well.  I have not tried a MMC
card.  EFSL does reduce the SPI clock during initialization, so it
may work with MMC cards as well.  But, I think I saw a mention
somewhere (perhaps on the SanDisk site) that the initialization
sequence for MMC and SD is slightly different.

Mike