Speaker Interfaces Configuration; Microphone Interfaces Configuration - SimCom SIM800 Hardware Design

"AT+CMIC" is used to adjust the input gain level of microphone. "AT+SIDET" is used to set the side-tone
level. In addition, "AT+CLVL" is used to adjust the output gain level. For more details, please refer to
document [1]
In order to improve audio performance, the following reference circuits are recommended. The audio signals
have to be layout according to differential signal layout rules as shown in following figures.
4.7.1.

Speaker Interfaces Configuration

SPKP
SPKN
Module
4.7.2.

Microphone Interfaces Configuration

MICP
MICN
Module
SIM800_Hardware Design_V1.10
33pF
10pF
33pF
10pF
33pF
10pF
Figure 30: Speaker reference circuit
The lines in bold type should
be accorded to differential
signal layout rules
Figure 31: Microphone reference circuit
35
Smart Machine Smart Decision
Close to speaker
33pF
10pF
33pF
10pF
33pF
10pF
These components should
be placed to microphone
as close as possible
ESD
33pF
10pF
33pF
10pF
Microphone
ESD
33pF
10pF
ESD
ESD
Electret
2018-08-13