MPC563XM Reference Manual, Rev. 1
1104
Freescale Semiconductor
Preliminary—Subject to Change Without Notice
Section 24.5.2.6, “EQADC Result FIFO Pop Registers (EQADC_RFPR)
24.7.4
Modifying Queues
More CQueues may be needed than the six supported by the EQADC. These additional CQueues can be
supported by interrupting command transfers from a configured CFIFO, even if it is TRIGGERED and
transferring, modifying the corresponding CQueue in the RAM or associating another CQueue to it, and
restarting the CFIFO. More details on disabling a CFIFO are described in
1.
Determine the resumption conditions when later resuming the scan of the CQueue at the point
before it was modified.
a.
Change MODEx in
Section 24.5.2.7, “EQADC CFIFO Control Registers (EQADC_CFCR)
Section 24.6.4.6.1, “Disabled Mode
for a description of what happens when
MODEx is changed to Disabled.
b.
Poll CFSx until it becomes IDLE in
Section 24.5.2.12, “EQADC CFIFO Status Register
c.
Section 24.5.2.10, “EQADC CFIFO Transfer Counter Registers
for later resuming the scan of the queue. The TC_CFx provides the point
of resumption.
d.
Since all result data may not have being stored in the appropriate RFIFO at the time MODEx
is changed to disable, wait for all expected results to be stored in the RFIFO/RQueue before
reconfiguring the DMAC to work with the modified RQueue. The number of results that must
return can be estimated from the TC_CFx value obtained above.
2.
Disable the DMAC from responding to the DMA request generated by CFFFx and RFDFx in
Section 24.5.2.9, “EQADC FIFO and Interrupt Status Registers (EQADC_FISR)
.
3.
Write “0x0000” to the TC_CFx field.
4.
Load the new configuration and conversion commands into RAM. Configure the DMAC to support
the new CQueue/RQueue, but do not configure it yet to respond to DMA requests from
CFIFOx/RFIFOx.
5.
Section 24.5.2.8, “EQADC Interrupt and DMA Control Registers
6.
Write “1” to CFINVx in
Section 24.5.2.7, “EQADC CFIFO Control Registers (EQADC_CFCR)
invalidate the entries of CFIFOx. Perform any other modifications to EQADC_CFCR except
changing MODEx from Disabled.
7.
Configure the DMAC to respond to DMA requests generated by CFFFx and RFDFx.
8.
Change MODEx to the modified CFIFO operation mode. Write “1” to SSEx to trigger CFIFOx if
MODEx is software trigger.