6.10.9 McASP
The Multi-channel Audio Serial Port (McASP) module functions as a general-purpose audio serial port optimized for the needs of multichannel audio applications. The McASP supports transmission and reception of time-division multiplexed (TDM) and Inter-IC Sound (I2S) protocols. In addition, it supports intercomponent digital audio interface transmission (DIT).
The McASP consists of transmit and receive sections that may operate synchronized, or completely independently with separate master clocks, bit clocks, and frame syncs, and using different transmit modes with different bit-stream formats. The McASP module also includes up to 16 serializers that can be individually enabled to either transmit or receive.
The device integrates three McASP modules (McASP0, McASP1, and McASP2) with:
- McASP0 supporting 16 serializers with independent TX/RX clock zones
- McASP1 supporting 10 serializers with independent TX/RX clock zones
- McASP2 supporting 6 serializers with independent TX/RX clock zones
Each McASP module includes the following main features:
- Up to 16 individually assignable serializers, each with its own data pins (AXR)
- A single 32-bit buffer per serializer for transmit and receive operations
- 2x interconnect slave interface ports:
- A configuration (CFG) port
- 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.
- Configurable functional clocks:
- May be generated internally (master mode)
- May be supplied by an external device (slave mode)
- May be divided down internally
- Independent transmit and receive modules, each providing:
- 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.
- Support for wide variety of I2S and similar bit-stream formats
- 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 (1 per direction) per each McASP module:
- 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
- One transmit interrupt request common for all serializers per McASP module
- One receive interrupt request common for all serializers per McASP module
- Extensive error checking and recovery:
- Transmit underruns and receiver overruns due to the system not meeting real-time requirements
- Early or late frame sync in TDM mode
- DMA error due to incorrect programming
- McASP Audio FIFO (AFIFO):
- Provides additional data buffering
- Provides added tolerance to variations in host/DMA controller response times
- May be used as a DMA event pacer
- Independent Read FIFO and Write FIFO
- 256 bytes of RAM for each FIFO (read and write), where:
- 256 bytes = four 32-bit words per serializer in the case of 16 data pins
- 256 bytes = 64 32-bit words in the case of one data pin
- Option to bypass Write FIFO and/or Read FIFO independently
For more information, see section Multi-channel Audio Serial Port (McASP) in chapter Peripherals of the Device TRM.