NXP Semiconductors MWCT101 S Series, Reference Manual

Page: 293 / 1761

In this option, the DMA is configured to transfer the data using both minor and major
loops, but the processor is required to reactivate the channel by writing to the DMA
registers after every minor loop. For this option, the DMA channel must be disabled
in the DMA channel MUX.
• Use an always-enabled DMA source.
In this option, the DMA is configured to transfer the data using both minor and major
loops, and the DMA channel MUX does the channel reactivation. For this option, the
DMA channel should be enabled and pointing to an "always enabled" source. Note
that the reactivation of the channel can be continuous (DMA triggering is disabled)
or can use the DMA triggering capability. In this manner, it is possible to execute
periodic transfers of packets of data from one source to another, without processor
intervention.
15.5 Initialization/application information
This section provides instructions for initializing the DMA channel MUX.
15.5.1 Reset
The reset state of each individual bit is shown in Memory map/register definition . In
summary, after reset, all channels are disabled and must be explicitly enabled before use.
15.5.2 Enabling and configuring sources
To enable a source with periodic triggering:
1. Determine with which DMA channel the source will be associated. Note that only the
first 4 DMA channels have periodic triggering capability.
2. Clear the CHCFG[ENBL] and CHCFG[TRIG] fields of the DMA channel.
3. Ensure that the DMA channel is properly configured in the DMA. The DMA channel
may be enabled at this point.
4. Configure the corresponding timer.
5. Select the source to be routed to the DMA channel. Write to the corresponding
CHCFG register, ensuring that the CHCFG[ENBL] and CHCFG[TRIG] fields are
set.
Chapter 15 Direct Memory Access Multiplexer (DMAMUX)
MWCT101xS Series Reference Manual, Rev. 3, 07/2019
NXP Semiconductors 293