TOBY-L4 series - System Integration Manual
UBX-16024839 - R04
System description
Page 49 of 143
1.11.2
Digital audio interface
TOBY-L4 series modules include two 4-wire I
2
S digital audio interfaces:
I2S0 digital audio interface, consisting of the following pins:
I2S_TXD
data output
I2S_RXD
data input
I2S_CLK
bit clock input/output
I2S_WA
world alignment / synchronization signal input/output
I2S1 digital audio interface consisting of the following pins:
I2S1_TXD
data output
I2S1_RXD
data input
I2S1_CLK
bit clock input/output
I2S1_WA
world alignment / synchronization signal input/output
The second digital audio interface (I2S1) will be supported by future firmware versions.
Both I2S0 and I2S1 digital audio interfaces are suitable to transfer digital audio data with an external compatible
digital audio device, as an audio codec or as an audio digital signal processor.
The I
2
S interfaces can be alternatively set in different modes:
PCM mode (short synchronization signal): I
2
S word alignment signal is set high for 1 or 2 clock cycles for the
synchronization, and then is set low for 16 clock cycles according to the 17 or 18 clock cycles frame length.
Normal I
2
S mode (long synchronization signal): I
2
S word alignment is set high / low with a 50% duty cycle
(high for 16 clock cycles / low for 16 clock cycles, according to the 32 clock cycles frame length).
The I
2
S interface can be alternatively set in 2 different roles:
Master mode
Slave mode
The sample rate of transmitted/received words, which corresponds to the I
2
S word alignment / synchronization
signal frequency (<I2S_sample_rate>), can be alternatively set to:
8 kHz
11.025 kHz
12 kHz
16 kHz
22.05 kHz
24 kHz
32 kHz
44.1 kHz
48 kHz
96 kHz
192 kHz
The modules support I
2
S transmit and I
2
S receive data 16-bit words long, linear. Data is transmitted and read in
2’s complement notation. The MSB is transmitted and read first.
I
2
S clock signal frequency depends on the frame length, the sample rate and the selected mode of operation:
17 x <I2S_sample_rate> or 18 x <I2S_sample_rate> in PCM mode (short synchronization signal)
16 x 2 x <I2S_sample_rate> in Normal I2S mode (long synchronization signal)
