Hardware Design V1.01(091226)

SIM900 Hardware Design
Iout(max)= 10mA
GND Ground
Power on or power off
PIN NAME I/O DESCRIPTION DC CHARACTERISTICS
PWRKEY I Voltage input for PWRKEY.
PWRKEY should be pulled
low to power on or power off
the system. The user should
keep pressing the key for a
short time when power on or
power off the system because
the system need margin time
in order to assert the
software.
VILmax=0.15*VDD_EXT
VIHmin=0.85* VDD_EXT
VImax=VDD_EXT
VILmin= 0V
It is already
pulled up.
PWRKEY_O
UT
O Connecting PWRKEY and
PWRKEY_OUT for a short
time then release also can
power on or power off the
module.
VOHmin= VDD_EXT-0.1V
VOLmax=0.1V
VOHmax= VDD_EXT
VOLmin= 0V
Audio interfaces
PIN NAME I/O DESCRIPTION DC CHARACTERISTICS COMMENT
MIC_P
MIC_N
I Positive and negative voice
band input
Audio DC Characteristics refer to
chapter 3.9
If unused keep
open
SPK_P
SPK_N
O Positive and negative voice
band output
If unused keep
open
LINEIN_R
LINEIN_L
I Line input If unused keep
open
GERNERAL PURPOSE input/output
PIN NAME I/O DESCRIPTION DC CHARACTERISTICS COMMENT
STATUS O Indicate working status If unused keep
open
NETLIGHT O Indicate net status If unused keep
open
DISP_DATA I/O
DISP _CLK O
DISP _CS O
DISP _D/C O
Display interface
If unused keep
open
SCL O I
2
C bus clock
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
SIM900_HD_V1.01 26.12.2009
17