
Cinterion
®
LTE Terminals Hardware Interface Description
3.6 GPIO Interface
47
ELSxT_HID_v04
2018-09-04
Confidential / Preliminary
Page 34 of 102
3.6.2.1
Solutions for the Digital Audio Interface (DAI/PCM)
The Digital Audio Interface is only supported in ELS61T-E2.
show an
example of using the digital audio interface of the LTE Terminal. The below mentioned sample
Nuvoton codec W681360 can be replaced with a DSP. In the example, framesync and clock
master is the module (FSC line) and thus the GSM network.
Figure 13:
Block circuit for DAI/PCM to analog converter
This DAI/PCM analog converter is well suited for evaluating and testing a telephone handset.
Figure 14:
Sample circuit for analog to DAI/PCM circuit
On the module side, the PCM interface has to be enabled. This can be done by using the fol-
lowing AT command: AT^SCFG="GPIO/mode/DAI","std".
Please note that level converters may be required between the the 3.0V audio codec interface
lines and the module‘s digital audio lines and - depending on VCCref settings for the GPIO in-
terface lines.
3.6.2.2
Audio Codec Board
The Audio Codec Board (
) is small in its footprint (3cm x 2,3 cm). It integrates a 3.3V
W681360
13-Bit-Linear-
CODEC
PCM to Analog Converter
LTE
Terminal
DIN
DOUT
FSC
BCLK
+3.0V
+3.0V
BCLK
DOUT
FSC
DIN
R5
1k
R6
1k
R9
100k
Mic1
MICROPHONE
1
2
+
C6
100uF
C3
10nF
C2
100nF
R8 100k
R7 20k
C1
100nF
U1
W681360
15
6
5
8
1
4
9
10
2
3
19
18
17
16
14
13
12
11
7
20
VSS
VDD
PO+
DR
VAGREF
PO-
BCLKR
PDI
RO-
PI
TI+
TI-
TG
HB
FST
DT
BCLKT
MCLK
FSR
VAG
R1 75k
R2 75k
C7 420pF
C8 420pF
R4 1k
R3 1k
C4 100nF
C5 100nF
LS1
SPEAKER
Speaker gain
LTE Terminal
Output lines:
FSC
BCLK
DOUT
Input line:
DIN