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UM10360_0
© NXP B.V. 2009. All rights reserved.
User manual
Rev. 00.06 — 5 June 2009
576 of 808
NXP Semiconductors
UM10360
Chapter 31: LPC17xx General Purpose DMA (GPDMA) controller
Note: The source and destination addresses must be aligned to the source and
destination widths.
shows the bit assignments of the DMACCxSrcAddr Registers.
5.18 DMA Channel Destination Address registers (DMACCxDestAddr -
0x5000 41x4)
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
enabled. When the DMA channel is enabled the register is updated as the destination
address is incremented and 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 that software has processed the value
read, the address may have progressed. It is intended to be read only when a channel has
stopped, in which case it shows the destination address of the last item read.
shows the bit assignments of the DMACCxDestAddr Register.
5.19 DMA Channel Linked List Item registers (DMACCxLLI - 0x5000 41x8)
The eight read/write DMACCxLLI Registers (DMACC0LLI to DMACC7LLI) contain a
word-aligned address of the next Linked List Item (LLI). If the LLI is 0, then the current LLI
is the last in the chain, and the DMA channel is disabled when all DMA transfers
associated with it are completed. Programming this register when the DMA channel is
enabled may have unpredictable side effects.
shows the bit assignments of
the DMACCxLLI Register.
5.20 DMA channel control registers (DMACCxControl - 0x5000 41xC)
The eight read/write DMACCxControl Registers (DMACC0Control to DMACC7Control)
contain DMA channel control information such as the transfer size, burst size, and transfer
width. Each register is programmed directly by software before the DMA channel is
enabled. When the channel is enabled the register is updated by following the linked list
when a complete packet of data has been transferred. Reading the register while the
channel is active does not give useful information. This is because by the time software
Table 542. DMA Channel Source Address registers (DMACCxSrcAddr - 0x5000 41x0)
Bit
Name
Function
31:0
SrcAddr
DMA source address. Reading this register will return the current source address.
Table 543. DMA Channel Destination Address registers (DMACCxDestAddr - 0x5000 41x4)
Bit
Name
Function
31:0
DestAddr
DMA Destination address. Reading this register will return the current destination
address.
Table 544. DMA Channel Linked List Item registers (DMACCxLLI - 0x5000 41x8)
Bit
Name
Function
1:0
-
Reserved, and must be written as 0.
31:2
LLI
Linked list item. Bits [31:2] of the address for the next LLI. Address bits [1:0] are 0.