Motorola DSP56012 Manual De Usuario

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 

).

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 

).

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

).