J�r�me Warnier wrote:
I was looking for some inexpensive IDE to CF converters on ebay, ended up buying some IDE with CF modules attached:
CF cards in embedded systems are very touchy if you have write access enabled. Basically if your power supply goes south during a write the meta-data on the CF card can become corrupted and it's trashed. I've had personal experience with this and read of many other reports of this.
To make a CF robust under write conditions there are specific signals that _must_ retain power during a write. A normal CF->IDE adapter will not do this for you.
Here's a piece I received outlineing the issue further:
We have information from a Compact Flash manufacturer that says you should have hardware to solve this problem - I do not believe there is a software solution. The problem is caused by the fact (as you state) that CF stores metadata in the flash blocks along with the disk block data. If the metadata is corrupted by an aborted write, it can affect all of the disk blocks stored in the flash block, and the metadata can even be so corrupt that you lose unrelated blocks. Our most common scenario for failure is to lose disk block #0, which, of course, is the boot block for our OS. We solve this using hardware. You need to use buffers to disconnect the CF's ATA reset, output-enable and write-enable signals from their source on the bus, and hold up DC power to the pull-ups, the buffers and the CF itself for at least 10ms-20ms after detecting the imminent loss of power. This is being implemented in our new hardware designs, and we have not yet gotten one back from fabrication to test. But it sure looks like it will work to solve the problem. Alan Mimms, Senior Architect F5 Networks, Inc. Spokane Development Center Liberty Lake, Washington v: 509-343-3524 f: 509-343-3501
-- Richard A. Smith [EMAIL PROTECTED]
