New MPC5200 Eratta/ATA Bugs

Stephen Warren SWarren at
Tue Apr 26 05:35:00 EST 2005

Eric N. Johnson (ACD) wrote:
> Freescale just realeased a new version of the eratta (hardware bugs) 
> document for the MPC5200.  It was posted last week, and adds some
> significant problems to the FEC Ethernet and IDE/ATA sections.
> Specifically, I'm wonder if Eratta ID 485 may be the cause of some of
> IDE issues we've been attributing to Bestcomm:
>   "During the concurrent access of ATA DMA READ and PCI or LPC the
>    ATA_ISOLATION signal can be incorrectly driven when ATA is paused."
> Unfortunately, their proposed workaround isn't appropriate for many 
> cases.  They suggest that you not use "ATA_ISOLATION" and connect the
> device directly to the LP bus without any buffering.  This could lead
> serious bus integrity issues, especially if the ATA device is
connected by 
> a ribbon cable. 

Freescale certainly confirmed that was the issue we were up against.

Freescale have been working with us on a board work-around for the
problem. This basically involves deriving a substitute ATA_ISOLATION
signal from the regular ATA control signals, in some cases.

Stephen Warren, Software Engineer, NVIDIA, Fort Collins, CO
swarren at
swarren at

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