User's Manual

SIM900B Hardware Design
Iout(max)= 10mA
GND Ground
Power on or power off
PIN NAME I/O DESCRIPTION DC CHARACTERISTICS
PWRKEY I Power on/off detect, active low. VILmax=0.9V
VIHmin=2.6V
VImax=3.3V
VILmin= 0V
It is already pulled
up internally (3V).
Audio interfaces
PIN NAME I/O DESCRIPTION DC CHARACTERISTICS COMMENT
MIC1P
MIC1N
I Positive and negative
voice-band input
MIC2P
MIC2N
I Auxiliary positive and negative
voice-band input
If unused keep
open
SPK1P
SPK1N
O Positive and negative
voice-band output
SPK2P
SPK2N
O Auxiliary positive and negative
voice-band output
Audio DC Characteristics
refer to chapter 3.9.4
If unused keep
open
AGND Analog ground Separate ground
connection for
external audio
circuits.
If unused keep
open.
Display interface
PIN NAME I/O DESCRIPTION DC CHARACTERISTICS COMMENT
DISP_RST O
DISP_DATA I/O
DISP _CLK O
DISP _CS O
DISP _D/C O
Display interface VILmax=0.15 *VDD_EXT
VIHmin=0.85*VDD_EXT
VILmin= 0V
VIHmax= VDD_EXT
VOHmin= VDD_EXT-0.1V
VOLmax=0.1V
VOHmax= VDD_EXT
VOLmin= 0V
If unused keep
open
General purpose input/output
GPIO1/ KBC4 I/O Default as GPIO,can be
multiplexed as keypad
VILmax=0.15 *VDD_EXT
VIHmin=0.85*VDD_EXT
If unused keep
open
SIM900B_HD_V1.03 24.06.2010
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