Application Interface; Pin Description - SimCom SIM900B Hardware Design

3 Application Interface

3.1

Pin Description

Table 4: Pin description
Pin name Pin number
Power supply
VBAT 1,2,3,4,5,6,7,8
VRTC 15
VDD_EXT 17
AGND 50，51
9,10,11,12,13,
GND
14
Power on/down
PWRKEY 34
Audio interfaces
MIC1P 53
MIC1N 55
SPK1P 54
SPK1N 56
MIC2P 57
MIC2N 59
SPK2P 58
SPK2N 60
Status
NETLIGHT 30
LCD interface
DISP _CLK 20
DISP_DATA 18
DISP _D/C 24
SIM900B_Hardware Design_V2.01
I/O Description
I Power supply
I/O Power supply for RTC
O 2.8V output power supply
Analog ground
Ground
PWRKEY should be pulled low at least
I 1 second and then released to power
on/down the module.
I Differential audio input
O Differential audio output
I Differential audio input
O Differential audio output
O Network status
O Display interface
I/O
O
12
Smart Machine Smart Decision
Comment
It is recommended to
connect with a battery or
a capacitor (e.g. 4.7uF).
If it is unused, keep open.
Separate ground
connection for external
audio circuits. If unused
connect to GND
directory.
VILmax=0.9V
VIHmin=2.6V
VImax=3.3V
VILmin= 0V
It has been pulled up
internally (3V).
If these pins are unused,
keep open.
If these pins are unused,
keep open.
2012-05-07