Enhanced Queued Analog-to-Digital Converter (eQADC)
MPC5510 Microcontroller Family Reference Manual, Rev. 1
Freescale Semiconductor
31-79
Preliminary
command register. The following steps illustrate how to configure CFIFO5 as an immediate command
CFIFO. This eliminates the use of the eDMA. The results will be returned to RFIFO5.
1. Configure the
Section 31.3.3.7, “eQADC Interrupt and eDMA Control Registers 0–5
a) Clear CFIFO fill enable5 (CFFE5 = 0) in EQADC_IDCR5.
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_IDCR5.
2. Configure the
Section 31.3.3.6, “eQADC CFIFO Control Registers 0–5 (EQADC_CFCRn)
.”
a) Write 1 to CFINV5 in EQADC_CFCR5. This will invalidate the contents of CFIFO5.
a) Set MODE5 to continuous-scan software trigger mode in EQADC_CFCR5.
3. To transfer a command, write it to the eQADC CFIFO push register 5 (EQADC_CFPR5) with
message tag = 0b0101. Refer to
Section 31.3.3.4, “eQADC CFIFO Push Registers 0–5
4. Up to 4 commands can be queued in CFIFO5. Check the CFCTR5 status in EQADC_FISR5 before
pushing another command to avoid overflowing the CFIFO. Refer to
FIFO and Interrupt Status Registers 0–5 (EQADC_FISRn)
.”
5. When the eQADC receives a conversion result for RFIFO5, it generates an interrupt request.
RFIFO pop register 5 (EQADC_RFPR5) can be popped to read the result. Refer to
Section 31.3.3.5, “eQADC Result FIFO Pop Registers 0–5 (EQADC_RFPRn)
31.5.4
Modifying Queues
More command queues may be needed than the six supported by the eQADC. These additional command
queues can be supported by interrupting command transfers from a configured CFIFO, even if it is
triggered and transferring, modifying the corresponding command queue in the RAM or associating
another command queue to it, and restarting the CFIFO. More details on disabling a CFIFO are described
in
Section 31.4.3.5.1, “Disabled Mode
.”
1. Determine the resumption conditions when later resuming the scan of the command queue at the
point before it was modified.
a) Change EQADC_CFCRn[MODE
n
Section 31.3.3.6, “eQADC CFIFO Control Registers
Section 31.4.3.5.1, “Disabled Mode
,” for a
description of what happens when MODE
n
is changed to disabled.
b) Poll EQADC_CFSR[CFS
n
Section 31.3.3.11, “eQADC CFIFO
”).
c) Read and save EQADC_CFTCRn[TC_CF
n
]
(see
Section 31.3.3.9, “eQADC CFIFO Transfer
Counter Registers 0–5 (EQADC_CFTCRn)
”) for later resuming the scan of the queue. The
TC_CF
n
provides the point of resumption.
d) Since all result data may not have being stored in the appropriate RFIFO at the time MODE
n
is changed to disable, wait for all expected results to be stored in the RFIFO/result queue before
