Ublox TOBY-L2 series, Руководство по системной интеграции

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TOBY-L2 and MPCI-L2 series - System Integration Manual
UBX-13004618 - R28 System description Page 56 of 164
The I 2 S interface can be set to two modes, by the <I2S_mode> parameter of the AT+UI2S command:
 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 31 or 30 clock cycles according to the 32
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 modules support I 2 S master role only: the I2S_CLK clock and the I2S_WA world alignment
synchronization signal are generated by the module.
The sample rate of transmitted/received words, which corresponds to the I
2 S word alignment
synchronization signal frequency, can be set by the <I2S_sample_rate> parameter of AT+UI2S to:
 8 kHz
 16 kHz
The modules support I 2 S transmit and I 2 S receive data 16-bit words long, linear, mono. Data is
transmitted and read in 2’s complement notation. MSB is transmitted and read first.
I
2 S clock signal frequency is set to 32 x <I2S_sample_rate>: the frame length, which corresponds to
the I 2 S word alignment / synchronization signal period, is 32 I 2 S clock cycles long.
☞
For the complete description of the possible configurations and settings of the I 2 S digital audio
interface for PCM and Normal I 2 S modes refer to the u-blox AT Commands Manual [3] , +UI2S AT
command.
The internal audio processing system is summarized in Figure 26 : external digital audio devices can
be interfaced directly to the digital signal processing part via the I 2 S digital interface. Audio
processing can be controlled by AT commands: see Audio Interface and Audio Parameters Tuning
sections in the u-blox AT Commands Manual
[3] .
EC HFP
To
Radio TX
From
Radio RX
RES NS
DRC LPF EQ AGC
I2S_RXD
I2S_TXD
Volume &
Mute
CNG
AGC EQ LPF DRC
NS HPF
Volume &
Mute
PCM
Player
Tone
Generator
PAM
Legend:
EC = Echo Cancellation
RES = Residual Echo Suppression
NS = Noise Suppression
LPF = Low Pass Filter
HPF = High Pass Filter
EQU = Equalizer
AGC = Additional Gain Control
DRC = Dynamic Range
Compression
CNG = Comfort Noise Generator
TOBY-L2
Figure 26: TOBY-L2 modules internal audio processing system block diagram
☞
The internal audio processing system of TOBY-L2 modules does not support the side-tone.