Ublox TOBY-R2 Series, System Integration Manual

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TOBY-R2 series - System integration manual
UBX-16010572 - R10 Design-in Page 113 of 151
 Cirrus Logic / Wolfson Microelectronics
 Nuvoton Technology
 Asahi Kasei Microdevices
 Realtek Semiconductor
Figure 64 and Table 48 describe an application circuit for the I2S digital audio interface providing basic
voice capability using an external audio voice codec, in particular the Maxim MAX9860 audio codec.
 DAC and ADC integrated in the external audio codec respectively converts an incoming digital data
stream to analog audio output through a mono amplifier and converts the microphone input signal
to the digital bit stream over the digital audio interface,

A digital side-tone mixer integrated in the external audio codec provides loopback of the
microphones/ADC signal to the DAC/headphone output.
 The module’s I2S interface (I2S master) is connected to the related pins of the external audio
codec (I2S slave).
 The GPIO6 of the TOBY-R2 series module (that provides a suitable digital output clock) is
connected to the clock input of the external audio codec to provide clock reference.
 The external audio codec is controlled by the TOBY-R2 series module using the DDC (I2C) interface,
which can concurrently communicate with other I2C devices and control an external audio codec.

The V_INT output supplies the external audio codec, defining proper digital interfaces voltage
level.
 Additional components are provided for EMC and ESD immunity : a 10 nF bypass capacitor and a
series chip ferrite bead noise/EMI suppression filter provided on each microphone line input and
speaker line output of the external codec as described in
Figure 64 and Table 48 . The necessity of
these or other additional parts for EMC improvement may depend on the specific application
board design.
Specific AT commands are available to configure the Maxim MAX9860 audio codec: for more details
see the u-blox AT commands manual
[2] , +UEXTDCONF AT command.
As various external audio codecs other than the one described in Figure 64 / Table 48 can be used to
provide voice capability, the appropriate specific application circuit has to be implemented and
configured according to the particular external digital audio device or audio codec used and according
to the application requirements.
TOBY-R2 series
(except “42” / “82” product
versions)
R2 R1
BCLK
GND
U1
LRCLK
Audio
Codec
SDIN
SDOUT
SDA
SCL
MCLK
IRQn
R3
C3 C2 C1
VDD
1V8
MICBIAS
C4
R4
C5
C6
MICLN
MICLP
D1
Microphone
Connector
MIC
C12 C11
J1
MICGND
R5
C8 C7
D2
SPK Speaker
Connector
OUTP
OUTN
J2
C10 C9 C14 C13
EMI3
EMI4
EMI1
EMI2
GPIO6
55
SDA
54
SCL
61
GND
5 V_INT
52
I2S_CLK
50
I2S_WA
51
I2S_TXD
53
I2S_RXD
Figure 64: I2S interface application circuit with an external audio codec to provide voice capability