Enhanced Queued Analog-to-Digital Converter (eQADC)
MPC5510 Microcontroller Family Reference Manual, Rev. 1
Freescale Semiconductor
31-77
Preliminary
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 0–5 (EQADC_CFCRn)
.”
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 ADC0. The received results will be placed in RFIFO3 and then moved to result
queue 1 by the eDMA.
31.5.2
eQADC/eDMA Controller Interface
This section provides an overview of the EQADC/eDMA interface and general guidelines about how the
eDMA should be configured in order for it to correctly transfer data between the queues in system memory
and the EQADC FIFOs.
31.5.2.1
Command Queue/CFIFO Transfers
In transfers involving command queues and CFIFOs, the eDMA moves data from a queued source to a
single destination as shown 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 eDMA has transfer control
descriptors (TCDs) containing these addresses and other parameters used in the control of data transfers
(See
Section 12.3.2.16, “Transfer Control Descriptor (TCD)
” for more information). For every eDMA
request issued by the EQADC, the eDMA must be configured to transfer a single command (32-bit data)
from the command queue, pointed to by the source address, to the CFIFO push register, pointed to by the
destination address. After the service of an eDMA 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
“Enhanced Direct Memory Access (eDMA)
” for details about how this functionality is supported.
•
The corresponding eDMA 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 command queue. This is desirable for CFIFOs in continuous scan mode, or in some cases,
for CFIFOs in single scan mode.
