UM11029
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© NXP Semiconductors N.V. 2017. All rights reserved.
User manual
Rev. 1.0 — 16 June 2017
261 of 515
NXP Semiconductors
UM11029
Chapter 16: LPC84x DMA controller
16.3.2 Trigger outputs
Each channel of the DMA controller provides a trigger output. This allows the possibility of
using the trigger outputs as a trigger source to a different channel in order to support
complex transfers on selected peripherals. This kind of transfer can, for example, use
more than one peripheral DMA request. An example use would be to input data to a
holding buffer from one peripheral, and then output the data to another peripheral, with
both transfers being paced by the appropriate peripheral DMA request. This kind of an
operation is called “chained operation” or “channel chaining”.
16.3.3 DMA requests
DMA requests are directly connected to the peripherals. Each channel supports one DMA
request line and one trigger input which is multiplexed to many possible input sources.
For each trigger multiplexer DMA_ITRIG_INMUXn, the following sources are supported:
•
ADC sequence A interrupt ADC_SEQA_IRQ.
•
ADC sequence B interrupt ADC_SEQB_IRQ.
•
SCT DMA request 0 SCT_DMA0.
•
SCT DMA request 1 SCT_DMA1.
•
ACMP_O comparator output.
•
GPIO pin interrupt 4 (PININT4).
•
GPIO pin interrupt 5 (PININT5).
•
GPIO pin interrupt 6 (PININT6).
•
GPIO pin interrupt 7 (PININT7).
•
CTIMER32 MR0 match DMA request (T0_DMAREQ_M0).
•
CTIMER32 MR1 match DMA request (T0_DMAREQ_M1).
•
Two choices of one of the DMA output triggers.
Table 295. DMA requests
DMA channel #
Request input
DMA trigger multiplexer
0
USART0_RX_DMA
DMA_ITRIG_INMUX0
1
USART0_TX_DMA
DMA_ITRIG_INMUX1
2
USART1_RX_DMA
DMA_ITRIG_INMUX2
3
USART1_TX_DMA
DMA_ITRIG_INMUX3
4
USART2_RX_DMA
DMA_ITRIG_INMUX4
5
USART2_TX_DMA
DMA_ITRIG_INMUX5
6
USART3_RX_DMA
DMA_ITRIG_INMUX6
7
USART3_TX_DMA
DMA_ITRIG_INMUX7
8
USART4_RX_DMA
DMA_ITRIG_INMUX8
9
USART4_TX_DMA
DMA_ITRIG_INMUX9
10
SPI0_RX_DMA
DMA_ITRIG_INMUX10
11
SPI0_TX_DMA
DMA_ITRIG_INMUX11
12
SPI1_RX_DMA
DMA_ITRIG_INMUX12