User's Manual

SIM900B EVB User Guide
SIM900B-EVB_UGD_V1.01 9 14.04.2010
3.2 Audio Interface
Figure 5： Audio Interface
Headset interface:
Pin Signal I/O Description
1 MIC1P I Positive microphone input
2 SPK1P O Positive speak output
3 SPK1N O Negative speak output
4 MIC1N I Negative microphone input
Earphone interface:
Pin Signal Input/Output Description
5 MIC2P&SPK2P I/O Auxiliary positive input and output