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
(rechargeable or non-chargeable) through the VRTC.
Note: If the RTC function is enabled, a battery or capacitor should be connected with the VRTC pin.
Otherwise the VRTC pin can be keep open.
The following figures show various sample circuits for RTC backup.
Figure 16: RTC supply from non-chargeable battery
Figure 17: RTC supply from rechargeable battery
Figure 18: RTC supply from capacitor
SIM900_HD_V1.01 26.12.2009
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