Enhanced Queued Analog-to-Digital Converter (EQADC)MPC5644A Microcontroller Reference Manual, Rev. 61006 Freescale Semiconductor— Supports configurable digital filter— Supports controls to bypass the trigger digital filters• Two Triggers operation mode for queue0— Additional internal trigger (not filtered) called Advance trigger that is used to enable theexternal trigger of queue0 and to control the loop behavior of CFIFO0• Supports 4 to 8 external 8-to-1 muxes which can expand the input channel number from 40 to 96• Upgrades the functionality provided by the QADC25.3 Modes of operationThis section describes the operation modes of the EQADC.25.3.1 Normal modeThis is the default operational mode when the EQADC is not in streaming mode or background debug orstop mode.25.3.2 Streaming modeThis mode is characterized by two main aspects: the abort action by CFIFO0 in any current conversionprocess started from another queue, and the loop behavior of the CFIFO0.In some applications, there may be sequences of identical commands each spaced only by a fewmicroseconds. To reduce the DMA data transfer, in this mode a short command queue can be stored inCFIFO0 and repeatedly be executed based on a timed trigger, but advance to the next (repeating) sequenceof commands based on another device’s internal trigger.The CFIFO0 delivers commands to the ADC as before, but those commands are not ‘invalidated’ after theyare sent (in fact, they are ‘invalidated’ only because the Transfer Next Data Pointer has moved on). Whenit encounters these repeated commands the CFIFO0 only fills once, using the DMA as usual, until eitherit is full or a command with End-of-Queue is encountered. Thereafter the sub-queue repeats/wraps. Thenumber of commands loaded is unaffected by the delivery of commands once the streaming mode isconfigured, since no commands loaded are invalidated even if sent before all the queue is loaded.The number of entries in the CFIFO0 is extended to eight (configurable). This is to facilitate the targetedapplications. The repeating subqueue must be contained within the eight CFIFO0 entries.To maintain compatibility, CFIFO0 by default operates as it does before, without streaming and with fourentries. Streaming, and additional entries, can be enabled independently.Streaming mode is selected as another mode for queue 0 using the configuration bits in theEQADC_CFCR register. Streaming mode makes use of an additional bit in the Conversion CommandWord (CCW); this bit is called ‘Repeat’. The purpose of this bit is to mark in the command queue, whereto start a repeating sequence.Streaming mode requires two trigger inputs. The standard queue 0 trigger, in this mode referred to as‘Repeat Trigger’ and a second internal trigger input to the eQADC called ‘Advance’ trigger.
