This section introduces the multichannel audio serial port (McASP) module and describes its main functions and connections in the device.
The McASP functions as a general-purpose audio serial port optimized to the requirements of various audio applications. The McASP module can operate in both transmit and receive modes. The McASP is useful for time-division multiplexed (TDM) stream, Inter-IC Sound (I2S) protocols reception and transmission as well as for an intercomponent digital audio interface transmission (DIT). The McASP has the flexibility to gluelessly connect to a Sony/Philips digital interface (S/PDIF) transmit physical layer component.
Although intercomponent digital audio interface reception (DIR) mode (i.e. S/PDIF stream receiving) is not natively supported by the McASP module, a specific TDM mode implementation for the McASP receivers allows an easy connection to external DIR components (for example, S/PDIF to I2S format converters).
The device have integrated eight McASP modules with:
- McASP1 and McASP2 supporting
up to 16 channels
with independent TX/RX clock/sync domain
- McASP3 through McASP8 modules
supporting up to 4 channels with independent TX/RX clock/sync domain
Figure 24-108 shows the McASP modules in the device.
McASP module includes the following main features:
- Two modules (McASP1 and McASP2) supporting up to 16 channels each and independent TX/RX clock/sync domains.
- Six modules (McASP3, McASP4,
McASP5, McASP6, McASP7, and McASP8) supporting up to 4 channels each and unified
clock/sync domain.
- Independent serializer for each
AXRx channel of each McASPx module.
- Idle request/acknowledge
protocol
- A single 32-bit buffer per
serializer for transmit and receive operations
- 2 x interconnect slave interface
ports:
- A configuration (CFG)
port supplied with an internal L4-interconnect interface clock
- A slave DMA data port
synchronized with functional clock
- Two independent clock generator
modules for transmit and receive.
- Clocking flexibility
allows the McASP to receive and transmit at different rates. For
example, the McASP can receive data at 48 kHz but output up-sampled data
at 96 kHz or 192 kHz.
- McASP module functional clock can
be generated:
- internally (master
mode)
- supplied over McASP
serial interface (slave mode)
- has a controllable
functional clock divide ratio
- Independent transmit and receive
modules, each includes:
- Programmable clock and
frame sync generator.
- TDM streams from 2 to 32,
and 384 time slots.
- Support for time slot
sizes of 8, 12, 16, 20, 24, 28, and 32 bits.
- Data formatter for bit
manipulation.
- Glueless connection to audio
analog-to-digital converters (ADC), digital-to-analog converters (DAC), codec,
digital audio interface receiver (DIR), and S/PDIF transmit physical layer
components.
- Wide variety of I2S and similar
bit-stream format.
- Integrated digital audio
interface transmitter (DIT):
- S/PDIF, IEC60958-1, AES-3
formats.
- Enhanced channel
status/user data RAM.
- 384-slot TDM with external
digital audio interface receiver (DIR) device.
- For DIR reception, an
external DIR receiver integrated circuit should be used with I2S output
format and connected to the McASP receive section.
- Support for 2x DMA requests (one
per direction):
- 1 level-sensitive
transmit direct memory access (DMA) request common for all of the McASP
serializers
- 1 level-sensitive receive
direct memory access (DMA) request common for all of the McASP
serializers
- All transmit DMA requests
are mapped to the device DMA crossbar
- One transmit interrupt request
common for all serializers
- One receive interrupt request
common for all serializers
- Each of the Rx and Tx interrupts
is propagated to different host processors via the device Interrupt
Crossbar
Note: Because a serializer receive and transmit channels data is shared on the same McASP data pin, user can choose to have either Tx or Rx function from a serializer, not both at the same time.