Adc; Ri Behaviors - SimCom SIM900B Hardware Design

3.10 ADC

SIM900B 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 10: ADC specification
Parameter
Voltage range
ADC Resolution
Sampling rate

3.11 RI Behaviors

Table 11: RI Behaviors
State RI response
Standby High
The pin is changed to low. When any of the following events occurs, 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 occurs, 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].
The behavior of the RI pin is shown in the following figure when the module is used as a receiver.
SIM900B_Hardware Design_V2.01
Min
0
-
-
Figure 26: RI behaviour of voice calling as a receiver
Typ Max
- 2.8
10 -
- 200K
30
Smart Machine Smart Decision
Unit
V
bits
Hz
2012-05-07