Ublox TOBY-R2 Series, System Integration Manual, Page: 52 / 151

TOBY-R2 series - System integration manual
UBX-16010572 - R10 System description Page 52 of 151
1.10 Audio
☞
Audio interface is not supported by TOBY-R2 series modules "42" / "82" product versions.
1.10.1 Digital audio over I2S interface
TOBY-R2 series modules include a 4-wire I2S digital audio interface (I2S_TXD data output, I2S_RXD
data input, I2S_CLK clock input/output, I2S_WA world alignment / synchronization signal
input/output), which can be configured by AT command for digital audio communication with external
digital audio devices as an audio codec (for more details see the u-blox AT commands manual
[2] ,
+UI2S AT command).
The I2S interface can be alternatively set in different modes, by <I2S_mode> parameter of AT+UI2S
command:
 PCM mode (short synchronization signal): I2S 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 I2S mode (long synchronization signal): I2S 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 I2S interface can be alternatively set in different roles, by <I2S_Master_Slave> parameter of
AT+UI2S:
 Master mode
 Slave mode
The sample rate of transmitted/received words, which corresponds to the I2S word alignment /
synchronization signal frequency, can be alternatively set by the <I2S_sample_rate> parameter of
AT+UI2S to:
 8 kHz
 11.025 kHz
 12 kHz
 16 kHz
 22.05 kHz
 24 kHz

32 kHz
 44.1 kHz
 48 kHz
The modules support I2S transmit and I2S receive data 16-bit words long, linear, mono (or also dual
mono in Normal I2S mode). Data is transmitted and read in 2’s complement notation. MSB is
transmitted and read first.
I2S 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)
☞
For the complete description of the possible configurations and settings of the I2S digital audio
interface for PCM and Normal I2S modes refer to the u-blox AT commands manual
[2] , +UI2S AT
command.