Enhanced Queued Analog-to-Digital Converter (EQADC)
27-122
Freescale Semiconductor
PXR40 Microcontroller Reference Manual, Rev. 1
•
The destination address should be updated to point to the next location where new coming results
are stored, which can be the first entry of the current RQueue (cyclic queue), or the beginning of a
new RQueue.
Figure 27-75. RQueue/RFIFO Interface
27.8.3
Sending Immediate Command Setup Example
In the EQADC, there is no immediate command register for sending a command immediately after writing
to that register. However, a CFIFO can be configured to perform the same function as an immediate
command register. The following steps illustrate how to configure CFIFO5 as an immediate command
CFIFO. The results will be returned to RFIFO5.
1.
Configure the
Section 27.6.2.6, 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 from
RFIF05.
d.
Set RFIFO Drain Enable5 (RFDE5 = 1) in EQADC_IDCR2.
2.
Configure the
Section 27.6.2.5, EQADC CFIFO Control Registers (EQADC_CFCR)
.
a.
Write “1” to CFINV5 in EQADC_FCR2. This will invalidate the contents of CFIFO5.
b.
Set MODE5 to Continuous-Scan Software Trigger mode in EQADC_CFCR2.
3.
To transfer a command, write it to EQADC CFIFO Push Register 5 (EQADC_CFPR5) with
Message Tag = 0b0101. Refer to
Section 27.6.2.3, EQADC CFIFO Push Registers
4.
Up to four commands can be queued in CFIFO5. Check the CFCTR5 status in EQADC_FISR5
before pushing another command to avoid overflowing the CFIFO. Refer to
Result 1
Result 2
Result 3
.....
Result n-1
Result n
RFPRx
RQueue in
system memory
RFIFO
Pop Register
One result transfer per DMA
request
Source Address
Destination Address
Summary of Contents for PXR4030
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