SIM900D Hardware Design
Table16: Pin description (Amphenol SIM card holder)
Pin Name
Signal
Description
C1
SIM_VDD
SIM Card Power supply, it can identify automatically the SIM Card power
mode
，
one is 3.0V±10%, another is 1.8V±10%. Current is about 10mA.
C2
SIM_RST
SIM Card Reset.
C3
SIM_CLK
SIM Card Clock.
C5
GND
Connect to GND.
C6
VPP
Not connect.
C7
SIM_DATA
SIM Card data I/O.
3.12 LCD Display Interface
SIM900D provides a serial LCD display interface that supports serial communication with LCD device. When
used as LCD interface, the following table is the pin definition. LCD interface timing should be united with the
LCD device.
Table17: Pin Definition of the LCD interface
*Note: This function is not supported in the default firmware. There must be some customized firmware if you
want. Please contact SIMCom for more details.
The DISP_RST can select the KBR0 or GPO0, in addition to the KBR0 or GPO0 there is no another function.
3.13
ADC
SIM900D provides one auxiliary ADC0 (General purpose analog to digital converter.) as voltage input pin, which
can be used to detect the values of some external items such as voltage, temperature etc. User can use AT
command “AT+CADC” to read the voltage value on ADC. For detail of this AT command, please refer to
document [1].
Table18: ADC specification
MIN
Type
MAX
Units
Voltage range
0
-
2.8
V
ADC Resolution
-
10
-
bits
Sampling rate
-
-
200K
Hz
Pin Name
Pin Number
Function
DISP_CLK
13
Display clock for LCD
DISP_DATA
14
Display data output
DISP_D/C
16
Display data or command select
DISP_CS
46
Display enable
SIM900D_HD_V1.02
09.04.2010
46
