miniSD card on RCM3900

I am trying to migrate from the RCM3315 to the 3900 for a logging device. Previously I used battery backed ram for the file system. This worked well because the logging data comes in bursts too fast to log to serial flash. The 3900 was selected for the SD card, which with its native intelligence should be able to handle the throughput as well as to provide 1G storage as opposed to about 200K for BB ram.

I can’t access the SD card at all with either of the sample programs SD_FLASH_INSPECT.C or FMT_DEVICE.C- they both return an ‘I/O error’ (-5) from the fat_AutoMount() call. This is a ‘catchall’ type error & I don’t know the cause. I am using Dynamic C 9.62.

The questions are:

  1. Will a 4G card (smallest I can find easily) cause this error?
  2. I am using unmodified FAT_CONFIG.LIB file- does this need any changes? For BB ram I had to modify the MEMCONFIG.LIB file to specify FS2_RAM_RESERVE as non-zero.
  3. The FAT_CONFIG.LIB file has a comment at line 220 saying
    //*** IMPORTANT! For removable devices use NULL label (“”)
    Do i need to change the next line to
    #define _DRIVER_1 “”
    instead of
    #define _DRIVER_1 “SD_FAT.LIB” ?

Everything else is working fine, this is the last hurdle before product release & I would really appreciate any help. I’m a new member & this is my first post.

I don’t know if the SD card code supports SDHC cards which is what most of the cards over 2GB seem to be. There are some 4GB SD cards but they are non standard as the spec for standard SD cards tops out at 2GB AFIK.

I’d try a smaller, standard SD card and see how that goes.


Thanks for your suggestion. I got some 1G cards and they work fine. This was my own dumb mistake, the RCM3900 manual states that 1G is the limit. I will say that there is only one sentence in the (lengthy!) manual to that effect, it’s nowhere in the samples. Other users, avoid my error & use 1G cards (even though they’re getting harder to find)!

Regards to all,