
UM10800
All information provided in this document is subject to legal disclaimers.
© NXP Semiconductors N.V. 2016. All rights reserved.
User manual
Rev. 1.2 — 5 October 2016
168 of 487
NXP Semiconductors
UM10800
Chapter 12: LPC82x DMA controller
–
If channel x is configured to auto reload the descriptor on exhausting of the
descriptor (bit RELOAD in the transfer configuration of the descriptor is set), then
enable 'clear trigger on descriptor exhausted' by setting bit CLRTRIG in the
channel's transfer configuration in the descriptor.
•
For channel y:
–
Configure the input trigger input mux register (DMA_ITRIG_INMUX[0:17]) for
channel y to use any of the available DMA trigger muxes (DMA trigger mux 0/1).
–
Configure the chosen DMA trigger mux to select DMA channel x.
–
Enable hardware triggering by setting bit HWTRIGEN in the channel configuration
register.
–
Set the trigger type to edge sensitive by clearing bit TRIGTYPE in the channel
configuration register.
–
Configure the trigger edge to falling edge by clearing bit TRIGPOL in the channel
configuration register.
Note that after completion of channel x the descriptor may be reloaded (if configured so),
but remains un-triggered. To configure the chain to auto-trigger itself, setup channels x
and y for channel chaining as described above. In addition to that:
•
A ping-pong configuration for both channel x and y is recommended, so that data
currently moved by channel y is not altered by channel x.
•
For channel x:
–
Configure the input trigger input mux register (DMA_ITRIG_INMUX[0:17]) for
channel y to use the same DMA trigger mux as chosen for channel y.
–
Enable hardware triggering by setting bit HWTRIGEN in the channel configuration
register.
–
Set the trigger type to edge sensitive by clearing bit TRIGTYPE in the channel
configuration register.
–
Configure the trigger edge to falling edge by clearing bit TRIGPOL in the channel
configuration register.
12.6 Register description
The DMA registers are grouped into DMA control, interrupt and status registers and DMA
channel registers. DMA transfers are controlled by a set of three registers per channel, the
CFG[0:20], CTRLSTAT[0:20], and XFERCFG[0:20] registers.
The reset value reflects the data stored in used bits only. It does not include the content of
reserved bits.
Table 153. Register overview: DMA controller (base address 0x5000 8000)
Name
Access
Address
offset
Description
Reset
Value
Reference
Global control and status registers
CTRL
R/W
0x000
DMA control.
0
INTSTAT
RO
0x004
Interrupt status.
0
SRAMBASE
R/W
0x008
SRAM address of the channel configuration table.
0