Some clarification in using the CCS mmc drivers for microSD

arunb · Joined: 08 Sep 2003 Posts: 492 Location: India

Hi,

Can the MMC driver in PICC folder be used for a microSD card ??, if not what changes would be required ?

thanks
arunb

asmallri · Joined: 12 Aug 2004 Posts: 1634 Location: Perth, Australia

arunb · Joined: 08 Sep 2003 Posts: 492 Location: India

I used the mmc_spi.c driver code.

I uses the driver without modification to the initialisation and read routines, but while writing to the card , the spi state remained busy. So I increased the timeout for waiting , this solved the problem.

It seems the mmc driver works very well for the microSD card.

Are the initialisation procedures for MMC and microSD card different ?? If so how come it works for me ??

thanks
arunb

PS: Thank you for the offer. I will consider it some time in the future, when my application would need greater features such as FAT16 support etc.

asmallri · Joined: 12 Aug 2004 Posts: 1634 Location: Perth, Australia

arunb · Joined: 08 Sep 2003 Posts: 492 Location: India

There is another file mmcsd.c, this supports both MMC and SD cards.
But no such thing is mentioned in the mmc_spi.c file. So I assume this meant only for a MMC card.

Also the mmc_spi.c driver did not work for the microSD card, the card initialised correctly, mmc_read_block also worked, mmc_write_block managed to write data to the card but returned error " mmc spi is busy" .

When I checked the status of the DI pin in the microSD card, it was high, so I assumed that the timeout needed to be increased, which I set to 3000 instead of 1000.

Now the drivers work perfectly.

thanks
arunb