Texas Instruments serial audio communication peripheral
A Multichannel Audio Serial Port (McASP) is a communication peripheral in digital signal processor (DSP) and microcontroller unit (MCU) components from Texas Instruments.[1]
An McASP functions as a general-purpose audio serial port optimized for the needs of multichannel audio applications. Depending on the implementation, an McASP may be useful for time-division multiplexed (TDM) streaming, inter-integrated circuit sound (I2S) protocol, and intercomponent digital audio interface transmission (DIT). However, some implementations are limited to I2S.[2]
An 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. An 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.
Features
Features of an McASP include:
Two independent clock generator modules for transmit and receive
Clocking flexibility allows an McASP to receive and transmit at different rates. For example, an 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
Individually assignable serial data pins (up to 16 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 I2S and similar bit-stream format
Integrated digital audio interface transmitter (DIT) supports:
Wide variety of I2S and similar bit-stream formats
TDM streams from 2 to 32 time slots
TDM stream of 384 time slots specifically designed for easy interface to external digital interface receiver (DIR) device transmitting DIR frames to McASP using the I2S protocol (one time slot for each DIR subframe)
The transmit and receive sections may each be individually programmed to support the following options
on the basic serial protocol:
Programmable clock and frame sync polarity (rising or falling edge): ACLKR/X, AHCLKR/X and AFSR/X
Slot length (number of bits per time slot): 8, 12, 16, 20, 24, 28, 32 bits supported
Word length (bits per word): 8, 12, 16, 20, 24, 28, 32 bits; always less than or equal to the time slot length
