Integration Manual

TOBY-L3 series - System Integration Manual
TSD-19090601 - R13 System Integration Manual Page 53 of 143
1.11 Digital Audio interfaces
TOBY-L3 series modules provide a 4-wire I
2
S digital audio interface:
 I2S digital audio interface, consisting of the following pins:
o I2S_TXD data output
o I2S_RXD data input
o I2S_CLK bit clock input/output
o I2S_WA world alignment / synchronization signal input/output
The I2S0 digital audio interfaces is 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 Digital Audio interface can be configured as I2S (I2S0) or PCM (PCM0) interface by means of open
CPU API or AT command, for communication with external devices with the following configuration is listed
in the Table 15:
I2S Mode (I2S0)
PCM Mode (PCM0)
I2S_TXD; I2S0 Transmit Data Out
PCM0_DOUT; PCM0 Data Out
I2S_RXD; I2S0 Receive Data In
PCM0_DIN; PCM0 Data In
I2S_CLK; I2S0 Serial Clock
PCM0_CLK; PCM0 Clock
I2S_WA; I2S0 Word Alignment
PCM0_SYNC; PCM0 Frame Sync
Table 15: TOBY-L3 series modules Digital Audio PINs configuration
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
 16 kHz
 48 kHz