Intel PXA26X User Manual Page 183

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Intel® PXA26x Processor Family Developer’s Manual 5-25
Direct Memory Access Controller
5.4 Examples
This section contains examples that show how to:
Set up and start a channel
Initialize a descriptor list for a channel that is running
Add a descriptor to the end of a descriptor list for a channel that is running
Initialize a channel that is going to be used by a direct DMA master
20 Reserved – Read as unknown and must be written as zero.
19 Reserved – Read as unknown and must be written as zero.
18 ENDIAN
DEVICE ENDIAN-NESS (read / write):
0 – Byte ordering is little endian
1 – Reserved
17:16 SIZE
MAXIMUM BURST SIZE – Of each data transferred (read / write):
00 – Reserved
01 – 8 Bytes
10 – 16 Bytes
11 – 32 Bytes
If DCMDx[LENGTH] is less than DCMDx[SIZE] the data transfer size equals
DCMDx[LENGTH].
15:14 WIDTH
WIDTH OF THE ON-CHIP PERIPHERAL (read / write/):
00 – Reserved
01 – 1 byte
10 – HalfWord (2 bytes)
11 – Word (4 Bytes)
Must be programmed 00 for memory-to-memory moves or companion-chip related
operations.
13 Reserved – Read as unknown and must be written as zero
12:0 LENGTH
LENGTH OF TRANSFER IN BYTES (read / write):
Indicates the length of transfer in bytes. DCMD[LENGTH] = 0 means zero bytes for
Descriptor Fetch Mode only. DCMD[LENGTH] = 0 is an invalid setting for the No-Descriptor
Fetch Mode. The maximum transfer length is (8K-1) bytes. If the transfer involves any of
the internal peripherals, the length of the transfer must be an integer multiple of the width of
that peripheral.
Table 5-12. DCMDx Register Bitmap and Bit Definitions (Sheet 2 of 2)
0x4000_02xC DMA Command Register (DCMDx) DMAC
Bit
31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
INCSRCADDR
INCTRGADDR
FLOWSRC
FLOWTRG
RESERVED
STARTIRQEN
ENDIRQEN
RESERVED
RESERVED
ENDIAN
SIZE
WIDTH
RESERVED
LENGTH
Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
Bits Name Description
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