LSI Logic Confidential
Host DMA Registers
8-23
Copyright © 2001, 2002 by LSI Logic Corporation. All rights reserved.
The GO bit is cleared by hardware after the transfer is
completed.
Software that clears the GO bit when BSRD is clear
flushes the remaining contents of the host DMA transfer
FIFO to SDRAM and terminates the transfer without
generating an interrupt.
Clearing the GO bit when BSRD is set (outgoing transfer)
discards the remaining contents of the host DMA FIFO
and terminates the transfer. Software clearing the GO bit
in either direction will generate an interrupt if enabled
(IE bit is programmed to logic value 1). Since this flush
will take some time to complete, software should keep
polling the GO bit after writing zero until the GO bit reads
as zero to ensure that the last data has been written to
SDRAM.
During incoming transfers using the host DMA mode, the
host interface drops the last byte if the data was received
after the GO bit was cleared by software.
Note:
The GO bit should be cleared, only if necessary, and read
as zero before software changes the value of BSRD or any
other host DMA register other than the Stop Address
register.
1 = Start host DMA transfers
0 = Flush host DMA FIFO and terminate transfer without
interrupt
POL
2
If POL bit is set, then H_DMAREQ pin is active LOW;
otherwise, it is active HIGH.
0 = H_DMAREQ is active HIGH
1 = H_DMAREQ is active LOW
BSRD
Bitstream READ
1
If BSRD is set, the Host DMA transfers are read by the
system–that is, the data is being output by DoMiNo.
If BSRD is clear, the Host DMA transfers are written by
the system. BSRD should not be changed while the
GO bit is set.
1 = DMN-8600 processor outputs the DMA data
Содержание DMN-8600
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