Is a 512 byte buffer required to use a MMC card

[arunb]

Hi,

I read that an 512 byte buffer would be required to use a MMC card (in SPI mode).

Is it posible to use the card directly ??

I am using PIC 16F877/16F628 , PCM compiler .

thanks
arunb

[asmallri]

It depends. (how long is a piece of string?)

If you only want to read then you can read anywhere from 1 to 512 bytes in a single operation.

If you want to write you must start writing on a 512 byte boundary but can then write sequentially through the block enentually writing the entire 512 byte block.

If you require random access, for example if you want to be able to change the contents of an area within a 512 byte block, then you must read in the contents of the entire block, modify the area of interest then write out the entire block.

If you use something like a FRAM to buffer you page while you work on it then you can do it with a brain dead 16F type PIC. I assume you are using the 16F family because you have the PCM compiler. My suggestion, byte the bullet, and get the PCH compiler :-) then you can use an 18F series PIC with sufficient RAM to do the job.
_________________
Regards, Andrew

http://www.brushelectronics.com/software
Home of Ethernet, SD card and Encrypted Serial Bootloaders for PICs!!