Motorola DSP56012 - Manual (Page 39)

Overview
DSP56012 Architectural Overview
MOTOROLA DSP56012 User’s Manual 1-19
1.3.4.3 Serial Audio Interface (SAI)
The DSP can communicate with other devices through its serial audio interfaces. The
Serial Audio Interface (SAI) provides a synchronous full-duplex serial port for serial
connection with a variety of audio devices such as Analog-to-Digital (A/D)
converters, Digital-to-Analog (D/A) converters, Compact Disc (CD) devices, etc. The
SAI implements a wide range of serial data formats in use by audio manufacturers.
Examples are:
• I
2
S format (Philips)
• CDP format (Sony)
• MEC format (Matsushita)
• Most industry-standard serial A/D and D/A formats
The SAI consists of independent transmit and receive sections and a common baud
rate generator. The transmitter consists of three transmitters controlled by one
transmitter controller. This enables simultaneous data transmission to as many as
three stereo audio devices, or transmission of three separate stereo pairs of audio
channels. The receiver consists of two receivers and a single receive controller. This
enables simultaneous data reception from up to two stereo audio devices. The
transmit and receive sections are fully asynchronous and may transmit and receive at
different rates (see
Section 6, Serial Audio Interface ).
1.3.4.4 General Purpose I/O
The General Purpose Input/Output (GPIO) pins are used for control and handshake
functions between the DSP and external circuitry. The GPIO port has eight dedicated
pins (GPIO0–GPIO7) that are controlled through a memory-mapped register.
Associated with each GPIO pin is a data bit, a control bit, and a data direction bit that
configures the pin as an input or an output, open-collector or normal (see
Section 7,
GPIO ).
1.3.4.5 Digital Audio Transmitter (DAX)
The Digital Audio Transmitter (DAX) is a serial audio interface module that outputs
digital audio data in the AES/EBU, CP-340, and IEC958 formats. The DAX transmits
one frame (consisting of two sub-frames) of audio and non-audio data at a time.
However, the DAX data path is double buffered so the next frame data can be stored
in the DAX without affecting the frame currently being transmitted (see
Section 8,
Digital Audio Transmitter ).