Smart Machine Smart Decision
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.
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
MIC1P
52
Main Audio input positive
MIC1N
12
Main Audio input negative
SPK1P
53
Main Audio output positive
Main
SPK1N
13
Main Audio output negative
MIC2P
9
Secondary Audio input positive
MIC2N
10
Secondary Audio input negative
SPK2P
51
Secondary Audio output positive
Secondary
SPK2N
11
Secondary Audio output negative
SPK1P/1N output can directly drive 32
Ω
receiver, SIM800H internal has class-AB audio amplifier, the following
table is class-AB performance:
Table 14: Performance of audio amplifier
Conditions
Class-AB AMP
4.2V 8Ohm THD+N=1%
0.87W
3.4V 8Ohm THD+N=1%
0.53W
4.2V 8Ohm THD+N=10%
1.08W
3.4V 8Ohm THD+N=10%
0.65W
SPK2P/2N output can directly drive 8
Ω
speaker.
AT command “AT+CMIC” is used to adjust the input gain level of microphone. AT command “AT+SIDET”
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