Hardware Design V1.01(091226)
Table Of Contents
- Contents
- Version history
- 1 Introduction
- 2 SIM900 Overview
- 3 Application Interface
- 3.1 SIM900 Pin Description
- 3.2 Operating Modes
- 3.3 Power Supply
- 3.4 Power Up and Power Down Scenarios
- 3.5 Power Saving
- 3.6 Summary of State Transitions (except SLEEP mode)
- 3.7 RTC Backup
- 3.8 Serial Interfaces
- 3.9 Audio Interfaces
- 3.10 SIM Card Interface
- 3.11 LCD Display Interface
- 3.12 Keypad Interface
- 3.13 ADC
- 3.14 Behaviors of the RI
- 3.15 Network Status Indication
- 3.16 General Purpose Input Output (GPIO)
- 3.17 External Reset
- 3.18 PWM
- 3.19 I2C Bus
- 4 Antenna Interface
- 5 Electrical, Reliability and Radio Characteristics
- 6 Mechanics
SIM900 Hardware Design
SIM900_HD_V1.01 26.12.2009
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Figure 8: Timing of turn on system using PWRKEY
When power on procedure completes, the SIM900 will send out following result code to indicate the module is
ready to operate when set as fixed baud rate.
RDY
This result code does not appear when autobauding is active.
3.4.1.2 Turn on SIM900 Using the PWRKEY Pin and PWRKEY_OUT Pin (Power on)
User can turn on SIM900 by connecting PWRKEY Pin and PWRKEY_OUT Pin for a short time and then
release. The simple circuit illustrates as the following figures.
Turn On/Off Impulse
PWRKEY_OUT
PWRKEY
MODULE
SIM900
Figure 9: Turn on SIM900 using driving circuit