Lcd Display/Spi Interface; Adc; Ri Behaviors - SimCom SIM900D Hardware Design

C5 GND
C6 VPP
C7 SIM_DATA
C8 SIM_PRESENCE
4.9

LCD Display/SPI Interface

SIM900D provides a serial LCD display interface. It could also be used as SPI interface in the embedded AT
application. For details about embedded AT application, please refer to document [6].
Note: This function is not supported in the standard firmware. If user wants this function, the firmware must be customized.
Please contact SIMCom for more details.

4.10 ADC

SIM900D provides an auxiliary ADC, which can be used to measure the voltage. User can use AT command
"AT+CADC" to read the voltage value. For details of this AT command, please refer to document [1].
Table 13: ADC specification
Parameter
Voltage range
ADC Resolution
Sampling rate

4.11 RI Behaviors

Table 14: RI Behaviors
State RI response
Standby High
The pin is changed to low. When any of the following events occur, the pin will be changed
to high:
Voice call
（1）Establish the call
（2）Hang up the call
The pin is changed to low. When any of the following events occur, the pin will be changed
to high:
Data call
（1）Establish the call
（2）Hang up the call
The pin is changed to low, and kept low for 120ms when a SMS is received. Then it is
SMS
changed to high.
The pin is changed to low, and kept low for 120ms when some URCs are reported. Then it is
URC
changed to high. For more details, please refer to document [7].
SIM900D_Hardware Design_V2.02
Connect to GND
Not connect
SIM card data I/O
Detect SIM card presence
Min
0
-
-
37
Smart Machine Smart Decision
Typ Max
- 2.8
10 -
- 200K
Unit
V
bits
Hz
2012-05-07