Enhanced Queued Analog-to-Digital Converter (eQADC)MPC5566 Microcontroller Reference Manual, Rev. 2Freescale Semiconductor 19-115c) Read and save EQADC_CFTCRn[TC_CFn] (see Section 19.3.2.9, “eQADC CFIFO TransferCounter Registers 0–5 (EQADC_CFTCRn)”) for later resuming the scan of the queue. TheTC_CFn provides the point of resumption.d) Since all result data may not have being stored in the appropriate RFIFO at the time MODEnis changed to disable, wait for all expected results to be stored in the RFIFO/result queue beforereconfiguring the eDMA to work with the modified result queue. The number of results thatmust return can be estimated from the TC_CFn value obtained above.2. Disable the eDMA from responding to the eDMA request generated by EQADC_FISRn[CFFFn]and EQADC_FISRn[RFDFn] (see Section 19.3.2.8, “eQADC FIFO and Interrupt Status Registers0–5 (EQADC_FISRn)”).3. Write “0x0000” to the TC_CFn field.4. Load the new configuration and conversion commands into RAM. Configure the eDMA to supportthe new command/result queue, but do not configure it yet to respond to eDMA requests fromCFIFOn/RFIFOn.5. If necessary, modify the EQADC_IDCRn registers (see Section 19.3.2.7, “eQADC Interrupt andeDMA Control Registers 0–5 (EQADC_IDCRn)”) to suit the modified command queue.6. Write 1 to EQADC_CFCRn[CFINVn] (see Section 19.3.2.6, “eQADC CFIFO Control Registers0–5 (EQADC_CFCRn)”) to invalidate the entries of CFIFOn.7. Configure the eDMA to respond to eDMA requests generated by CFFFn and RFDFn.8. Change MODEn to the modified CFIFO operation mode. Write 1 to SSEn to trigger CFIFOn ifMODEn is software trigger.19.5.5 Command Queue and Result Queue UsageFigure 19-67 is an example of command queue and result queue usage. It shows the command queue 0commands requesting results that are stored in result queue 0 and result queue 1, and command queue 1commands requesting results that are stored only in result queue 1. Some command messages request datato be returned from the on-chip ADC/external device, but some only configure them and do not requestreturning data. When a command queue contains both write and read commands like command queue 0,the command queue and result queue entries are not aligned, in Figure 19-67, the result for the secondcommand of command queue 0 is the first entry of result queue 0. The figure also shows that commandqueue and result queue entries can also become unaligned even if all commands in a command queuerequest data as command queue 1. Command queue 1 entries became unaligned to result queue 1 entriesbecause a result requested by the forth command queue 0 command was sent to result queue 1. Thishappens because the system can be configured so that several command queues can have results sent to asingle result queue.
