Serial Audio Interface (Sai) - Motorola DSP56009 User Manual

1.3.4.3

Serial Audio Interface (SAI)

The DSP can communicate with other devices through the SAI. The 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 Disk (CD) devices, etc. The SAI implements a wide range of
serial data formats in use by audio manufacturers. Examples are:
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• I 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.
1.3.4.4 General Purpose Input/Output
The General Purpose Input/Output (GPIO) signals are used for control and
handshake functions between the DSP and external circuitry. The GPIO port has four
dedicated signals (GPIO0–GPIO3) that are controlled through a memory-mapped
register. Associated with each GPIO signal 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 for detailed information about GPIO operation.
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