CF Issues

Hi Matt,

We found that certain compact flash cards do not fully power-down when the power switch on the Altera boards is used to remove power from the compact flash socket. This is the root of the startup issues.

The desired start up sequence is as follows:

1. The board powers up and the card goes into memory mode. (We desire True IDE mode, but at this point have no control because the FPGA is not yet configured)

2. FPGA finishes its configuration and the operating system boots up.

3. The compact flash driver detects a card in the socket.

4. The compact flash driver toggles the power to the socket to reset the card.

5. When power returns the the card it will be in True IDE mode (once the FPGA is configured it can perform the required signalling to change card modes)

6. The compact flash driver recognises the card and all is well.

We run into a problem with step 4 when using some compact flash cards. When their power supply is toggled they still seem to draw power from other signals. Since they never truely power-down, when the power supply is restored, they do not enter True IDE mode and the driver does not properly recognise them. This generates the "Unable to initialize compact flash card. Please re-insert" error.

Unfortunately, the only way to power-down and properly configure these problem cards to True IDE mode is to remove them from the socket and re-insert them once the FPGA has configured itself.

Dennis Scott

Microtronix Datacom