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UM10316_0
© NXP B.V. 2008. All rights reserved.
User manual
Rev. 00.06 — 17 December 2008
525 of 571
NXP Semiconductors
UM10316
Chapter 30: LPC29xx General Purpose DMA (GPDMA) controller
5.15 DMA Channel registers
The channel registers are used to program the eight DMA channels. These registers
consist of:
•
Eight DMACCxSrcAddr Registers.
•
Eight DMACCxDestAddr Registers.
•
Eight DMACCxLLI Registers.
•
Eight DMACCxControl Registers.
•
Eight DMACCxConfig Registers.
When performing scatter/gather DMA, the first four of these are automatically updated.
5.16 DMA Channel Source Address Registers (DMACCxSrcAddr -
0xE014 01x0)
The eight read/write DMACCxSrcAddr Registers (DMACC0SrcAddr to DMACC7SrcAddr)
contain the current source address (byte-aligned) of the data to be transferred. Each
register is programmed directly by software before the appropriate channel is enabled.
When the DMA channel is enabled this register is updated:
•
As the source address is incremented.
•
By following the linked list when a complete packet of data has been transferred.
Reading the register when the channel is active does not provide useful information. This
is because by the time software has processed the value read, the address may have
progressed. It is intended to be read only when the channel has stopped, in which case it
shows the source address of the last item read.
Note: The source and destination addresses must be aligned to the source and
destination widths.
shows the bit assignments of the DMACCxSrcAddr Registers.
5.17 DMA Channel Destination Address registers (DMACCxDestAddr -
0xE014 01x4)
The eight read/write DMACCxDestAddr Registers (DMACC0DestAddr to
DMACC7DestAddr) contain the current destination address (byte-aligned) of the data to
be transferred. Each register is programmed directly by software before the channel is
Table 459. DMA Synchronization Register (DMACSync - 0xE014 0034)
Bit
Name
Function
15:0
DMACSync
Controls the synchronization logic for DMA request signals. Each bit represents one
set of DMA request lines as described in the preceding text:
0 - synchronization logic for the corresponding DMA request signals are disabled.
1 - synchronization logic for the corresponding request line signals are enabled.
Table 460. DMA Channel Source Address Registers (DMACCxSrcAddr - 0xE014 01x0)
Bit
Name
Function
31:0
SrcAddr
DMA source address. Reading this register will return the current source address.