SIM900 View Datasheet(PDF) - Unspecified

Part Name

Description

Manufacturer

SIM900

SIM900 Quad-band/SIM900A Dual-band GSM/GPRS module

Unspecified 

SIM900 Hardware Design

Table 17: ADC specification

Voltage range

ADC Resolution

Sampling rate

MIN

0

-

-

Type

-

10

-

MAX

2.8

-

200K

Units

V

bits

Hz

3.14 Behaviors of the RI

Table 18: Behaviours of the RI

State

Standby

Voice calling

RI respond

HIGH

Change LOW, then:

（1）Change to HIGH when establish calling.

（2）Use AT command ATH, the RI pin changes to HIGH.

（3）Sender hangs up, change to HIGH.

Data calling

SMS

URC

Change LOW, then：

（1）Change to HIGH when establish calling.

（2）Use AT command ATH, the RI changes to HIGH.

When receive SMS, The RI will change to LOW and hold low level about 120 ms, then

change to HIGH.

Some URCs triggers 120ms low level on RI. For more details, please refer to document [10]

If the module is used as caller, the RI will maintain high. However, when it is used as receiver, following is timing

of ring.

RI

HIGH

LOW

Power on Ring

MO or MT

Ring

Hang on

(talking)

MO or

MT

Ring

Hang up

Hang up

Figure 33: SIM900A Services as Receiver

SIM900_HD_V1.01

44

26.12.2009

Share Link: