m5m51016btp Renesas Electronics Corporation., m5m51016btp Datasheet - Page 119

• Manufacturer Part Number: m5m51016btp
• Description: Renesas 16-bit Single-chip Microcomputer M16c Family / M16c/20 Series
• Manufacturer: Renesas Electronics Corporation.

M30245 Group
Rev.2.00 Oct 16, 2006
REJ09B0340-0200
2.6 Serial sound interface
2.6.1 Overview
The Serial Sound Interface (SSI) is a synchronous serial data interface used primary for transferring
digital audio data. The bus of the 30245 Serial Sound Interface has four lines:
• Continuous serial clock (SCK)
• Word (channel) select (WS)
• Serial data out (XMIT)
• Serial data in (RX)
A basic Serial Sound Interface-based communication system has two Serial Sound Interfaces and a
master controller, which generates both SCK and WS. The Serial Sound Interface that generates the
control signals (SCK and WS) operates as a master, and the Serial Sound Interface that receives the
external control signals operates as slave. The 30245 Sound Serial Interface can operate only as a slave.
The transmitter/receiver must change channels on every WS transition. Through separate transmit and
receive pins, simultaneous transmit and receive can be performed in synchronization with the same SCK
and WS signals.
The following is an overview of the Serial Sound Interface.
Transmission/reception format
Select function
The data path is designed to work with the data format of the USB audio class device specifications.
The transmitter/receiver must change channels on every WS transition. The number of SCKs within a
WS high/low period is set as the channel width. The channel width can be selected from among 16
bits, 24 bits, and 32 bits using channel width select bits 0 and 1 (bits 4 and 5 of the SSIiMR0 register).
If the number of SCKs exceeds the channel width, the receiver will stop receiving data until the next
WS edge and the transmitter continues to transmit “0”. However, if the number of the SCKs falls short
of the channel data width, both the transmitter and the receiver will immediately switch to transmit and
receive, respectively, of the next channel data item.
In the Serial Sound Interface function, the following features can be selected.
(1) Rate feedback function
(2) Channel width selection function
When used with the USB interface, the Serial Sound Interface can count the number of WSs or SCKs
per USB frame. The count value is loaded into the serial sound interface xRF register (x = 0 or 1) on
the falling edge of each SOF pulse generated by the USB core. The SOF pulse is a frame delimiter
used in USB communication. The value read from the register is the count from the immediately
preceding USB frame.
Channel widths of 32, 24 and 16 bits can be used to transmit and receive data. The width can be
selected by the channel width select bits 0 and 1 in serial sound interface mode register 0.
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2. Serial sound interface