UM11029
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User manual
Rev. 1.0 — 16 June 2017
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NXP Semiconductors
UM11029
Chapter 16: LPC84x DMA controller
16.6.16 Channel configuration registers
The CFGn register contains various configuration options for DMA channel n.
See
for a summary of trigger options.
Table 317. Configuration registers for channel 0 to 24 (CFG[0:24], addresses 0x5000 8400 (CFG0) to address 0x5000
8564 (CFG24)) bit description
Bit
Symbol
Value Description
Reset
value
0
PERIPHREQEN
Peripheral request Enable. If a DMA channel is used to perform a
memory-to-memory move, any peripheral DMA request associated with that
channel can be disabled to prevent any interaction between the peripheral
and the DMA controller.
0
0
Disabled. Peripheral DMA requests are disabled.
1
Enabled. Peripheral DMA requests are enabled.
1
HWTRIGEN
Hardware Triggering Enable for this channel.
0
0
Disabled. Hardware triggering is not used.
1
Enabled. Use hardware triggering.
3:2
-
Reserved. Read value is undefined, only zero should be written.
NA
4
TRIGPOL
Trigger Polarity. Selects the polarity of a hardware trigger for this channel.
0
0
Active low - falling edge. Hardware trigger is active low or falling edge
triggered, based on TRIGTYPE.
1
Active high - rising edge. Hardware trigger is active high or rising edge
triggered, based on TRIGTYPE.
5
TRIGTYPE
Trigger Type. Selects hardware trigger as edge triggered or level triggered. 0
0
Edge. Hardware trigger is edge triggered. Transfers will be initiated and
completed, as specified for a single trigger.
1
Level. Hardware trigger is level triggered. Note that when level triggering
without burst (BURSTPOWER = 0) is selected, only hardware triggers
should be used on that channel.
Transfers continue as long as the trigger level is asserted. Once the trigger
is de-asserted, the transfer will be paused until the trigger is, again,
asserted. However, the transfer will not be paused until any remaining
transfers within the current BURSTPOWER length are completed.
6
TRIGBURST
Trigger Burst. Selects whether hardware triggers cause a single or burst
transfer.
0
0
Single transfer. Hardware trigger causes a single transfer.
1
Burst transfer. When the trigger for this channel is set to edge triggered, a
hardware trigger causes a burst transfer, as defined by BURSTPOWER.
When the trigger for this channel is set to level triggered, a hardware trigger
causes transfers to continue as long as the trigger is asserted, unless the
transfer is complete.
7
-
Reserved. Read value is undefined, only zero should be written.
NA