Enhanced Queued Analog-to-Digital Converter (EQADC)MPC5644A Microcontroller Reference Manual, Rev. 61160 Freescale Semiconductor25.7.2.2 RQueue/RFIFO transfersIn transfers involving RQueues and RFIFOs, the DMAC moves data from a single source to a queuedestination as showed in Figure 25-97. The location of the data to be moved is indicated by the sourceaddress, and the final destination for that data, by the destination address. For every DMA request issuedby the EQADC, the DMAC has to be configured to transfer a single result (16-bit data), pointed to by thesource address, from the RFIFO pop register to the RQueue, pointed to by the destination address. Afterthe service of a DMA request is completed, the destination address has to be updated to point to thelocation where the next 16-bit result will be stored. The source address remains unchanged. When the lastexpected result is written to the RQueue, one of the following actions is recommended.• The corresponding DMA channel should be disabled.• The destination address should be updated pointed to the next location where new coming resultsare stored, which can be the first entry of the current RQueue (cyclic queue), or the beginning of anew RQueue.Figure 25-97. RQueue/RFIFO Interface25.7.3 Sending immediate command setup exampleIn the EQADC, there is no immediate command register for sending a command immediately after writingto that register. However, a CFIFO can be configured to perform the same function as an immediatecommand register. The following steps illustrate how to configure CFIFO5 as an immediate commandCFIFO. The results will be returned to RFIFO5.1. Configure the Section 25.5.2.8, EQADC Interrupt and DMA Control Registers (EQADC_IDCR).a) Clear CFIFO Fill Enable5 (CFFE5 = 0) in EQADC_IDCR2.b) Clear CFIFO Underflow Interrupt Enable5 (CFUIE5 = 0) in EQADC_IDCR2.c) Clear RFDS5 to configure the EQADC to generate interrupt requests to pop result data fromRFIF05.d) Set RFIFO Drain Enable5 (RFDE5 = 1) in EQADC_IDCR2.Result 1Result 2Result 3.....Result n-1Result nRFPRxRQueue insystem memoryRFIFOPop RegisterOne result transfer per DMArequestSource AddressDestination Address
