MPC563XM Reference Manual, Rev. 1
Freescale Semiconductor
1101
Preliminary—Subject to Change Without Notice
b.
Set CFFS1 and RFDS3 to configure the EQADC to generate DMA requests to push commands
into CFIFO1 and to pop result data from RFIF03.
c.
Set CFINV1 to invalidate the contents of CFIFO1.
d.
Set RFDE3 and CFFE1 to enable the EQADC to generate DMA requests. Command transfers
from the RAM to the CFIFO1 will start immediately.
e.
Set RFOIE3 to indicate if RFIFO3 overflows.
f.
Set CFUIE1 to indicate if CFIFO1 underflows.
4. Configure MODE1 to continuous-scan rising edge external trigger mode in
“EQADC CFIFO Control Registers (EQADC_CFCR)
.
Step Four: Command transfer to ADCs and Result data reception.
When an external rising edge event occurs for CFIFO1, the EQADC automatically will begin
transferring commands from CFIFO1 when it becomes the highest priority CFIFO trying to send
commands to CBuffer1. The received results will be placed in RFIFO3 and then moved to RQueue1
by the DMAC.
24.7.2
EQADC/DMAC Interface
This section provides an overview about the EQADC/DMAC interface and general guidelines about how
the DMAC should be configured in order for it to correctly transfer data between the queues in system
memory and the EQADC FIFOs.
NOTE:
Advanced DMACs provide more functionality then the ones discussed in this
section. Refer to the block guide of the DMAC used at the SoC level for details.
24.7.2.1
CQueue/CFIFO Transfers
In transfers involving CQueues and CFIFOs, the DMAC moves data from a queued source to a single
destination as showed in
. The location of the data to be moved is indicated by the source
address, and the final destination for that data, by the destination address. The DMAC contains a data
structure containing these addresses and other parameters used in the control of data transfers. For every
DMA request issued by the EQADC, the DMAC has to be configured to transfer a single command (32-bit
data) from the CQueue, pointed to by the source address, to the CFIFO push register, pointed to by the
destination address. After the service of a DMA request is completed, the source address has to be updated
to point to the next valid command. The destination address remains unchanged. When the last command
of a queue is transferred one of the following actions is recommended. Refer to the DMAC block guide
for details about how this functionality is supported.
•
The corresponding DMA channel should be disabled. This might be desirable for CFIFOs in single
scan mode.
•
The source address should be updated to pointed to a valid command which can be the first
command in the queue that has just been transferred (cyclic queue), or the first command of any
other CQueue. This is desirable for CFIFOs in continuous scan mode, and at some cases, for
CFIFOs in single scan mode.