DMAMUX_CHCFGn field descriptions (continued)
Field Description
0 Triggering is disabled. If triggering is disabled and ENBL is set, the DMA Channel will simply route the
specified source to the DMA channel. (Normal mode)
1 Triggering is enabled. If triggering is enabled and ENBL is set, the DMAMUX is in Periodic Trigger
mode.
SOURCE DMA Channel Source (Slot)
Specifies which DMA source, if any, is routed to a particular DMA channel. See the chip-specific
DMAMUX information for details about the peripherals and their slot numbers.
21.4 Functional description
The primary purpose of the DMAMUX is to provide flexibility in the system's use of the
available DMA channels.
As such, configuration of the DMAMUX is intended to be a static procedure done during
execution of the system boot code. However, if the procedure outlined in Enabling and
configuring sources is followed, the configuration of the DMAMUX may be changed
during the normal operation of the system.
Functionally, the DMAMUX channels may be divided into two classes:
• Channels that implement the normal routing functionality plus periodic triggering
capability
• Channels that implement only the normal routing functionality
21.4.1
DMA channels with periodic triggering capability
Besides the normal routing functionality, the first 4 channels of the DMAMUX provide a
special periodic triggering capability that can be used to provide an automatic mechanism
to transmit bytes, frames, or packets at fixed intervals without the need for processor
intervention.
The trigger is generated by the periodic interrupt timer (PIT); as such, the configuration
of the periodic triggering interval is done via configuration registers in the PIT. See the
section on periodic interrupt timer for more information on this topic.
Chapter 21 Direct Memory Access Multiplexer (DMAMUX)
K22F Sub-Family Reference Manual, Rev. 4, 08/2016
NXP Semiconductors 417
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