NXP Semiconductors MPC5566, Reference Manual

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Enhanced Queued Analog-to-Digital Converter (eQADC)
MPC5566 Microcontroller Reference Manual, Rev. 2
Freescale Semiconductor 19-61
ADCs is considered completed when they are stored in the appropriate ADC command buffer. The transfer
of entries bound for the external device is considered completed when the serial transmission of the entry
is completed.
When the EQADC_CFPR n is written and CFIFO n is not full, the CFIFO counter CFCTR n is incremented
by 1, and the push next data pointer n then is incremented by 1 (or wrapped around) to point to the next
entry in the CFIFO.
When the EQADC_CFPR n is written but CFIFO n is full, the eQADC does not increment the counter value
and does not overwrite any entry in CFIFO n .
Figure 19-35. CFIFO Diagram
The detailed behavior of the push next data pointer and transfer next data pointer is described in the
example shown in
Figure 19-36 where a CFIFO with 16 entries is shown for clarity of explanation, the
actual hardware implementation has only four entries. In this example, CFIFO n with 16 entries is shown
in sequence after pushing and transferring entries.
Push Next
32-bit Entry 2
32-bit Entry 1
Control Signals
CFIFO
Transfer Counter
Control Logic
Data Pointer *
Transfer Next
Data Pointer *
CFIFO
Push Register
Data to
External
Device or
to On-Chip
ADCs
Write
to Bus
Interface
by CPU
or DMA
DMA Done
Interrupt/DMA Request
All CFIFO entries are memory mapped and the entries addressed by these pointers
can have their absolute addresses calculated using TNXTPTR and CFCTR. *