DMAMUX_CHCFGn field descriptions (continued)Field Description0 Triggering is disabled. If triggering is disabled and ENBL is set, the DMA Channel will simply route thespecified source to the DMA channel. (Normal mode)1 Triggering is enabled. If triggering is enabled and ENBL is set, the DMAMUX is in Periodic Triggermode.SOURCE DMA Channel Source (Slot)Specifies which DMA source, if any, is routed to a particular DMA channel. See the chip-specificDMAMUX information for details about the peripherals and their slot numbers.21.4 Functional descriptionThe primary purpose of the DMAMUX is to provide flexibility in the system's use of theavailable DMA channels.As such, configuration of the DMAMUX is intended to be a static procedure done duringexecution of the system boot code. However, if the procedure outlined in Enabling andconfiguring sources is followed, the configuration of the DMAMUX may be changedduring 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 triggeringcapability• Channels that implement only the normal routing functionality21.4.1 DMA channels with periodic triggering capabilityBesides the normal routing functionality, the first 4 channels of the DMAMUX provide aspecial periodic triggering capability that can be used to provide an automatic mechanismto transmit bytes, frames, or packets at fixed intervals without the need for processorintervention.The trigger is generated by the periodic interrupt timer (PIT); as such, the configurationof the periodic triggering interval is done via configuration registers in the PIT. See thesection on periodic interrupt timer for more information on this topic.Chapter 21 Direct Memory Access Multiplexer (DMAMUX)K22F Sub-Family Reference Manual, Rev. 4, 08/2016NXP Semiconductors 417
