Digital Voice Interface Application Note r0

LE866 DIGITAL VOICE INTERFACE APPLICATION NOTE 80471NT11521A Rev.0 • 2017-01-16 19 of 22
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7 ANNEX
I
2
S Bus Overview
This chapter provides a short description of the standard I2S bus. This standard suitably modified is
used by the DVI interface implemented on the Telit modules.
The standard I2S is an electrical serial bus designed for connecting digital audio devices. This popular
serial bus has been developed by Philips® in 1986 as a 3-wire bus for interfacing to audio chips such
as codecs. It is a simple data interface, without any form of address or device selection.
Refer to fig. 9: the I2S design handles audio data separately from clock signals. On an I2S bus, there
is only one bus master and one transmitter.
In high-quality audio applications involving a codec, the codec is typically the master so that it has
precise control over the I2S bus clock.
An I2S bus design consists of the following serial bus lines:
• SD: Serial Data
• WS: Word Select
• Serial Clock: SCK
The I2S bus carries two channels (left and right) 8 bit long, which are typically used to carry stereo
audio data streams. The data alternates between left and right channels, as controlled by the word
select signal driven by the bus master.
fig. 4: I2S Bus Configurations
clock SCK
word select WS
data SD
clock SCK
word select WS
data SD