SD card vs SDHC card?


Will SDHC cards work in the RCM4300 if I re-format them to FAT16? I realize that the card will have more capacity than the rabbit FAT16 filesystem can handle, but it seems like normal SD cards are getting harder to find than SDHC cards, and I want to make sure my device will work for many years into the future.


No, SDHC cards will not work if reformatted as FAT16. The Rabbit SD code uses the SPI interface on SD cards, which SDHC cards do not have.

Unfortunately, even non-SDHC SD cards larger than 1GB also don’t work with the current Rabbit code. This is because the sector size is hard-coded into their library, and cards larger than 1GB use sectors larger than 512. Even reformatting these cards to be <1GB doesn’t work.

Hopefully Rabbit will fix this problem in an upcoming release of Dynamic C. I emailed them several weeks ago asking if they intended to, but still haven’t heard anything back.

  • Taj

Thanks Taj, that’s too bad.