User's Manual

Cinterion
®
ELS31-VA/ELS51-VA Hardware Interface Description
2.1 Application Interface
56
 ELS31-VA_ELS51-VA_HID_v01.000 2017-01-04
Confidential / Preliminary
Page 33 of 106
2.1.9 Inter IC Sound Interface (I
2
S)
The I
2
S Interface is a standardized bidirectional I
2
S ("Inter-IC Sound Interface") based digital
audio interface for transmission of mono voice signals for telephony services.
The I
2
S interface can be enabled and configured using the AT command AT^SAIC (see [1]).
An activation is possible only out of call and out of tone presentation. The I
2
S properties and
capabilities comply with the requirements laid out in the Phillips I2S Bus Specifications, revised
June 5, 1996.
The I
2
S interface has the following characteristics:
• Bit clock mode: Slave, requires external master clock input
• Sampling rate: 8KHz (narrowband), 16KHz (wideband)
• 256kHz bit clock at 8kHz sample rate
• 512kHz bit clock at 16kHz sample rate
• Frame length: 32 bit stereo voice signal (16 bit word length)
The digital audio interface lines available for the PCM interface are also available for the I
2
S
interface. In I
2
S mode they have the same electrical characteristics.
Table 6 lists the available I
2
S interface signals, Figure 12 shows the I
2
S timing.
Figure 12: I
2
S timing (slave mode)
Table 6: Overview of I
2
S pin functions
Signal name on
SMT application
interface
Signal
configuration
inactive
Signal
direction:
Slave
Description
PCM_I2S_OUT PD O I
2
S data from ELS31-VA/ELS51-VA to external
codec
PCM_I2S_IN PD I I
2
S data from external codec to ELS31-VA/ELS51-
VA
PCM_I2S_FSC PD I Frame synchronization signal from external codec
Word alignment (WS)
PCM_I2S_CLK PD I Bit clock from external codec
PCM_I2S_CLK
PCM_I2S_OUT
PCM_I2S_IN
PCM_I2S_FSC
MSB
MSB
LSB
LSB
14 13
14 13
1
1
12
12
2
2
MSB
MSB
125 µs