
DMA Programming Model
MOTOROLA
DMA Controller Module
14-11
R/W
BITS
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
FIELD
RESERVED
RESET
R/W
MBAR + $308, MBAR + $348, MBAR + $388, MBAR + $3C8
Table 14-18 DMA Control Bit Descriptions
BIT NAME
DESCRIPTION
INT
The Interrupt on completion of transfer field determines whether an interrupt is generated at
the completion of the transfer or occurrence of an error condition.
0 = No interrupt is generated.
1 = Internal interrupt signal is enabled.
EEXT
Enable peripheral request. Collision could occur between the START bit and the REQUEST
signal when EEXT = 1. Therefore, caution should be exercised when initiating a DMA
transfer with the START bit while EEXT = 1.
0 = Peripheral request is ignored.
1 = Enables peripheral request to initiate transfer. Internal request is always enabled. It is
initiated by writing a 1 to the START bit
CS
Cycle steal.
0 = DMA continuous make read/write transfers until the BCR decrements to zero.
1 = Forces a single read/write transfer per request. The request may be processor by setting
the START bit, or periphery by asserting the REQUEST signal. (Can be generated by
the processor.)
AA
The auto-align bit and the SIZE bits determine whether the source or destination is
auto-aligned. Auto alignment means that the accesses are optimized based on the address
value and the programmed size. For more information, see
0 = Auto-align disabled.
1 = If the SSIZE bits indicate a larger or equivalent transfer size with respect to DSIZE, then
the source accesses are auto-aligned. If the DSIZE bits indicate a larger transfer size
than SSIZE, then the destination accesses are auto-aligned. Source alignment takes
precedence over destination alignment. If auto- alignment is enabled, the appropriate
address register increments, regardless of the state of DINC or SINC.
Table 14-17 DMA Control Register (DCR)—BCR24BIT = 0 (Continued)
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Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
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