User's Manual

M80 Hardware Design
M80_HD_V1.2 - 52 -
3.10. Audio interfaces
The module provides two analogy input channels and three analogy output channels.
Table 12: Pin definition of Audio interface
AIN1 and AIN2 can be used for input of microphone and line. An electret microphone is usually
used. AIN1 and AIN2 are both differential input channels.
AOUT1 is used for output of the receiver. This channel is typically used for a receiver built into a
handset. AOUT1 channel is a differential channel.
AOUT2 is typically used with earphone or speaker. It is a single-ended and mono channel. SPK2P
and AGND can establish a pseudo differential mode. If customer needs to play Melody or Midi
ring tone for incoming call, AOUT2 Channel should always be used. If it is used as a speaker, an
amplifier should be employed also.
AOUT3 is used for loud speaker output as it embedded an amplifier of class AB whose maximum
drive power is 800mW. AOUT3 is a differential channel. Immediately playing Melody or Midi
ring tone for incoming call is available in AOUT3.
These three audio channels can be swapped by “AT+QAUDCH” command. For more details,
please refer to document [1].
Use AT command “AT+QAUDCH” to select audio channel:
 0--AIN1/AOUT1, the default value is 0.
 1--AIN2/AOUT2
 2--AIN2/AOUT3
For each channel, customer can use AT+QMIC to adjust the input gain level of microphone.
Interface
Name
Pin
Description
AIN1/AOUT1
MIC1P
9
Channel one for Microphone positive input
MIC1N
10
Channel one for Microphone negative input
SPK1P
12
Channel one for Audio positive output
SPK1N
11
Channel one for Audio negative output
AIN2/AOUT2
MIC2P
7
Channel two for Microphone positive input
MIC2N
8
Channel two for Microphone negative input
SPK2P
5
Channel two for Audio positive output
AGND
6
Cooperate with SPK2P
AIN2/AOUT3
LOUDSPKP
14
Channel three for Audio positive output
LOUDSPKN
13
Channel three for Audio negative output