How are bad sectors in a MMC card detected ??

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

Hi,

I am using the CCS drivers for a MMC card. It works very well, except that a block write operation returns a MMC_EC_WRITE_ALWAYS_BUSY = 17 error.

I find that this happens after several blocks have been written.

Is it possible that some portions in the MMC are defective ??

Is there a way to detect this in advance ??

Note: I am directly reading and writing blocks to the MMC using the drivers.

thanks
arunb

asmallri · Joined: 12 Aug 2004 Posts: 1630 Location: Perth, Australia

MMC and SD cards include embedded wear leveling and bad sector detection and remapping logic. Until you have exceeded the endurance of the media you will not see these areas. Once you have exceeded the endurance then yes this could explain what you are seeing.

If you are using relatively new media and are not continuously writing to the same blocks then more likely you have a implementation problem.
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