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UM10360_0
© NXP B.V. 2009. All rights reserved.
User manual
Rev. 00.06 — 5 June 2009
575 of 808
NXP Semiconductors
UM10360
Chapter 31: LPC17xx General Purpose DMA (GPDMA) controller
5.16 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.
5.17 DMA Channel Source Address registers (DMACCxSrcAddr -
0x5000 41x0)
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.
3
DMASEL11
Selects the DMA request for GPDMA input 11:
0 - UART1 RX is selected.
1 - Timer 1match 1 is selected.
4
DMASEL12
Selects the DMA request for GPDMA input 12:
0 - UART2 TX is selected.
1 - Timer 2 match 0 is selected.
5
DMASEL13
Selects the DMA request for GPDMA input 13:
0 - UART2 RX is selected.
1 - Timer 2 match 1 is selected.
6
DMASEL14
Selects the DMA request for GPDMA input 14:
0 - UART3 TX is selected.
1 - Timer 3 match 0 is selected.
7
DMASEL15
Selects the DMA request for GPDMA input 15:
0 - UART3 RX is selected.
1 - Timer 3 match 1 is selected.
31:8
-
Reserved, user software should not write ones to reserved bits. The value read from a
reserved bit is not defined.
Table 541. DMA Request Select register (DMAReqSel - 0x4000 C1C4)
…continued
Bit
Name
Function