M12 Hardware Design
M12_Hardware_Design_V3.3
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9
8
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5
4
3
2
1
15
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8
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5
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4
26
2
27
13
18
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28
GND
TO PC serial port
SP3238
3V
GND
GND
T5OUT
/SHUTDOWN
V+
GND
V-
VCC
T4OUT
T2OUT
T3OUT
T1OUT
R3IN
R2IN
R1IN
/STATUS
3V
ONLINE
R1OUT
R2OUT
R3OUT
/R1OUT
GND
T5IN
T4IN
T3IN
T2IN
T1IN
C2+
C2-
C1-
C1+
MODULE
RXD
DTR
RTS
RI
CTS
TXD
DCD
Figure 26: RS232 level match circuit
3.9. Audio interfaces
The module provides two analogy input channels and two analogy output channels.
Table 10: Pin definition of Audio interface
Interface
Name
Pin
Function
(AIN1/AOUT1)
MIC1P
23
Microphone1 input +
MIC1N
24
Microphone1 input -
SPK1P
22
Audio1
SPK1N
21
Audio1 output-
(AIN2/AOUT2)
MIC2P
25
Microphone2 input +
MIC2N
26
Microphone2 input -
SPK2P
20
Audio2
AGND
19
It is suggested AGND is used in audio
circuit. Do not connect it to digital
ground in host PCB which could produce
TDD noise.
Quectel
Confidential