Smart Machine Smart Decision
SIM800H _Hardware Design_V2.03
33
2016-10-10
HIGH
LOW
Idle
Ring
Hang up the call
Establish the call
RI
Figure 27: RI behaviour of voice calling as a receiver
HIGH
LOW
Idle
RI
120ms
Receive SMS
URC
Figure 28: RI behaviour of URC or receive SMS
However, if the module is used as caller, the RI will remain high. Please refer to the following figure.
HIGH
LOW
Idle
Ring
Establish
the call
Hang up
the call
Idle
RI
Figure 29: RI behaviour as a caller
4.7.
Audio Interfaces
SIM800H provides two analog inputs (MIC1P/1N; MIC2P/2N), which could be used for electret microphone.
The module also provides two analog outputs (SPK1P/1N; SPK2P/2N).
Table 13: Audio interface definition
Pin name
Pin number
Function
Main
MIC1P
52
Main Audio input positive
MIC1N
12
Main Audio input negative
SPK1P
53
Main Audio output positive
SPK1N
13
Main Audio output negative
Secondary
MIC2P
9
Secondary Audio input positive
MIC2N
10
Secondary Audio input negative
SPK2P
51
Secondary Audio output positive
SPK2N
11
Secondary Audio output negative
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