Cirrus Logic EP93xx User Manual
Page 428
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DS785UM1
Copyright 2007 Cirrus Logic
DMA Controller
EP93xx User’s Guide
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DAH:
Destination Address Hold - This bit is used for external
M2P transfers where the external memory destination is a
memory-mapped FIFO-based device (with one address
location) or for internal peripheral transfers (M2P) to the
peripheral’s FIFO buffer.
1 - Hold the destination address throughout the transfer
(do not increment).
0 - Increment the destination address after each transfer in
the transaction.
SAH:
Source Address Hold - This bit is used for external DMA
transfers where the external memory source is a memory-
mapped FIFO-based device (with one address location) or
for internal register locations.
1 - Hold the source address throughout the transfer (do
not increment).
0 - Increment the source address after each transfer in the
transaction.
TM:
Transfer Mode:
00 - Software initiated DMA transfer.
01 - Hardware initiated external DMA transfer, that is,
transfer from memory to external device or to IDE or SSP.
10 - Hardware initiated external DMA transfer, that is,
transfer from external device (or IDE/SSP) to memory.
11 - Not used.
ETDP:
End-of-Transfer/Terminal Count pin Direction & Polarity:
00 - The DEOT/TC pin is programmed as an active low
end-of-transfer input.
01 - The DEOT/TC pin is programmed as an active high
end-of-transfer input.
10 - The DEOT/TC pin is programmed as an active low
terminal count output.
11 - The DEOT/TC pin is programmed as an active high
terminal count output.
DACKP:
DMA Acknowledge pin Polarity:
0 - DACK is active low.
1 - DACK is active high.
DREQP:
DMA Request pin Polarity. These bits must be set before
the channels ENABLE bit is set. Otherwise the reset
value, “00”, will cause the DMA to look for an active low,
level sensitive DREQ.
00 - DREQ is active low, level sensitive.
01 - DREQ is active high, level sensitive.
10 - DREQ is active low, edge sensitive.
11 - DREQ is active high, edge sensitive.