Chris Maryan

Compact Flash (ATA) Hot Swap on MCF5445x - CPU freeze

Discussion created by Chris Maryan on Mar 19, 2010
Latest reply on Jun 18, 2011 by Ammar Siddiqui

I have a 54454 design using a Compact Flash card attached directly to the ATA lines. When the CF card is inserted when the board is powered up (i.e. hot swapped), approximately 1/3 of the time the CPU will freeze (and eventually resets due to the watchdog). If the board is reset with the card in place, the CF card works perfectly. Has anyone else seen any issues with this?


  • The wiring is fairly straight forward and follows the various appnotes I've found on the subject. Basically a direct connection from the CF card holder, to the corresponding pin on the 54454 ATA bus, with pullups/downs where appropriate.
  • I have eliminated software being the issue. I can completely reduce the code running on the CPU to almost nothing (including no ATA interaction of any kind) and the probloem still occurs.
  • The only thing that seems to do the trick is killing power to the CF card, which obviously isn't terribly useful.
  • If the watchdog is disabled, the CPU becomes completely frozen. There are no exceptions, no bus faults, nothing at all.

Any ideas? Has anyone else successfully designed a CF interface on the 54454? If so, can you hot wap the card? Anyone perhaps have similar experiences with normal ATA devices (i.e. hot swapable HDs)?






Keywords: MCF54454, MCF54455, MCF5445x, 54454, 54455, 5445x, ATA, Compact Flash, CF, hot swap