AFIFO
Host
or DMA
controller
McASP
Rx DMA Req.
Tx DMA Req.
Rx DMA Req.
Tx DMA Req.
Data bus
Data bus
Write FIFO
32
32
Read FIFO
32
32
Peripheral configuration bus
Write FIFO Control Register
Write FIFO Status Register
Read FIFO Control Register
Read FIFO Status Register
Preliminary
Architecture
www.ti.com
10.2.8.1.4 Using the CPU for McASP Servicing
The CPU can be used to service the McASP through interrupt (upon AXINT/ARINT interrupts) or
through polling the XDATA bit in the XSTAT register. As discussed in
and
, the CPU can access through either the data port or through the configuration bus.
To use the CPU to service the McASP through interrupts, the XDATA/RDATA bit must be enabled in
the respective XINTCTL/RINTCTL registers, to generate interrupts AXINT/ARINT to the CPU upon data
ready.
10.2.8.2 McASP Audio FIFO (AFIFO)
The AFIFO contains two FIFOs: one Read FIFO (RFIFO), and one Write FIFO (WFIFO). To ensure
backward compatibility with existing software, both the Read and Write FIFOs are disabled by default.
See
for a high-level block diagram of the AFIFO.
The AFIFO may be enabled/disabled and configured via the WFIFOCTL and RFIFOCTL registers. Note
that if the Read or Write FIFO is to be enabled, it must be enabled prior to initializing the
receive/transmit section of the McASP (see
for details).
Figure 10-27. McASP Audio FIFO (AFIFO) Block Diagram
10.2.8.2.1 AFIFO Data Transmission
When the Write FIFO is disabled, transmit DMA requests pass through directly from the McASP to the
host/DMA controller. Whether the WFIFO is enabled or disabled, the McASP generates transmit DMA
requests as needed; the AFIFO is “invisible” to the McASP.
When the Write FIFO is enabled, transmit DMA requests from the McASP are sent to the AFIFO, which
in turn generates transmit DMA requests to the host/DMA controller.
If the Write FIFO is enabled, upon a transmit DMA request from the McASP, the WFIFO writes
WNUMDMA 32-bit words to the McASP if and when there are at least WNUMDMA words in the Write
FIFO. If there are not, the WFIFO waits until this condition has been satisfied. At that point, it writes
WNUMDMA words to the McASP. (See description for WFIFOCTL.WNUMDMA in
1044
Multichannel Audio Serial Port (McASP)
SPRUGX9 – 15 April 2011
© 2011, Texas Instruments Incorporated
Содержание TMS320C6A816 Series
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