8250 IDMA BD Len?

Penn, John jpenn at magisnetworks.com
Fri Mar 21 17:01:53 EST 2003


Does anybody know why the length field
of an 8250 IDMA BD would not contain the
number of bytes transferred before /DONE
is asserted.

This is a dual memory transfer from
the local bus to 60x memory.  I am
initially setting the BD length to 1752.
I can see the correct length in the bd_cnt
field in the parameter ram after /DONE has
asserted and the IDMA has invalidated the BD.

What I get is the original length I programmed
in, 1752.  The data is there and good.

DMA_WRAP = 64
SS_MAX = 32
STS = 4
DTS = 32

Thanks for the help.

John Penn

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