Are you using an SD card recommended by Digi?
The following miniSD™ Cards were evaluated by Rabbit Semiconductor for use with RCM4300 Rabbit-
Core modules and future Rabbit-based devices that support miniSD™ Cards, and were found to interface
correctly with these devices. While other miniSD™ Cards may work correctly with a PC, some cards have
exhibited lockup behavior under certain conditions when running in the SPI mode, which is used by the
RCM4300.
Memory size tested
Kingston 256MB, 512MB, 1GB
SanDisk 256MB, 512MB, 1GB
Toshiba 1 GB
Transcend 1 GB