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SPRUH91D–March 2013–Revised September 2016
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Multichannel Audio Serial Port (McASP)
Introduction
Purpose of the Peripheral
The multichannel audio serial port (McASP) functions as a general-purpose audio serial port optimized for
the needs of multichannel audio applications. The McASP is useful for time-division multiplexed (TDM)
stream, Inter-IC Sound (I2S) protocols, and 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. In addition, all of the McASP pins can be configured as
general-purpose input/output (GPIO) pins.
24.0.16 Features
Features of the McASP include:
• 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.
• 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
• Up to 16 individually assignable serial data pins:
– McASP0 can have up to 16 serial data pins
– McASP1 can have up to 12 serial data pins
– McASP2 can have up to 4 serial data pins
• 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 Inter-IC Sound (I2S) and similar bit-stream formats
• Integrated digital audio interface transmitter (DIT) supports (McASP2 only):
– S/PDIF, IEC60958-1, AES-3 formats
– Up to 4 transmit pins
– 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.
• 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
– Out-of-range high-frequency master clock for both transmit and receive
– External error signal coming into the AMUTEIN input
– 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)
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