MMCSD with capacity > 2gb PIC24

[hssn601]

i am using ccs driver for sd card and it works fine for 2gb memory card but now a days 2gb is not available so i need help how to use 4gb memory card with mmcsd.c

[Ttelmah]

Easiest solution, pay a little money, and buy the Brush electronics drivers.
A lot less than the time it'd take you to get >2GB working any other way, and they work.

Below 2GB, you are talking SD. There were a few (very few) cards that went to 4GB, still using the SD standard. Rare now (and getting rarer) used for a few products that came out before a standard was approved for >2GB. 99.9% of stuff above 2GB, switches to SDHC (high capacity), which changes certain parts of the SD spec to handle the higher capacities.

The CCS drivers support SD, but not SDHC.
It is possible to modify the CCS drivers to try to use SDHC, but it's a lot of work. The Brush drivers support SDHC, and correctly handle switching between the formats, allowing your device to use the larger cards.

2GB SD cards are still readily available, because there are a lot of cameras etc., which only support SD. Generally more common in micro-SD, since it is easier for the manufacturer to make one 'micro' card, and just sell the adapter, rather than making a 2GB SD, and also a 2GB micro-SD. Sandisk, Transcend, Kingston etc., all do 2GB drives readily available. If you don't need capacities above 2GB, then just source these.

I modified the older drivers to support SDHC, but then CCS changed the drivers, and I "couldn't be bothered" to fiddle around again, so bought the Brush drivers. Been totally reliable for me (happy customer). Andrew (the author) posts here.

Best Wishes

[hssn601]

It will be allot work for me to integrate another driver in my code .. i need help how to modify mmcsd.c to work for SDHC, i need to know only initialization sequence is different or something else i need to worry about.

[Ttelmah]

It shouldn't be much work to change the driver. Basic functions are the same whatever driver you use. Initialisation, open, close, read file etc..

Much more work to try to get the CCS code to handle SDHC. Probably at least 20* as much work....

The whole flowchart changes to add the detection of the high capacity bit, and switching modes when this is present, in the CID phase., and of course the driver has to be able to support switching between FAT16, and FAT32 automatically. Lots of minor parts change, like the size of erase block on the card etc.. You are talking rewriting 90% of the driver.

If you want to try, then pull the SD card data sheets, but be prepared for how long this is going to take. Get the V2 SD card host controller specification (full) data sheet.

[hssn601]

Solution.

http://www.ccsinfo.com/forum/viewtopic.php?t=52490
_________________
Best Regards,
Hassan Shakeel