hardware design v1 00 2
Table Of Contents
- Contents
- Version History
- 1 Introduction
- 2 SIM900R Overview
- 3 Package Information
- 4 Application Interface
- 4.1 Power Supply
- 4.2 Power on/down Scenarios
- 4.3 Power Saving Mode
- 4.4 RTC Backup
- 4.5 Serial Interfaces
- 4.6 Audio Interfaces
- 4.7 SIM Card Interface
- 4.8 LCD Display/SPI Interface
- 4.9 Keypad Interface
- 4.10 ADC
- 4.11 RI Behaviours
- 4.12 Network Status Indication
- 4.13 General Purpose Input/Output (GPIO)
- 4.14 External Reset
- 4.15 PWM
- 4.16 I2C Bus
- 4.17 Antenna Interface
- 5 Electrical, Reliability and Radio Characteristics
- 5.1 Absolute Maximum Ratings
- 5.2 Recommended Operating Conditions
- 5.3 Digital Interface Characteristics
- 5.4 SIM Card Interface Characteristics
- 5.5 VDD_EXT Characteristics
- 5.6 SIM_VDD Characteristics
- 5.7 VRTC Characteristics
- 5.8 Current Consumption (VBAT = 3.8V)
- 5.9 Electro-Static Discharge
- 5.10 Radio Characteristics
- 6 Manufacturing
- Appendix
Smart Machine Smart Decision
4.13 General Purpose Input/Output (GPIO)
SIM900R provides up to 12 GPIO pins. The output voltage level of the GPIO can be set by the AT command
“AT+ SGPIO”. The input voltage level of the GPIO can also be read by the AT command “AT+ SGPIO”. For
more details, please refer to document [1].
Table 14: Pin definition of the GPIO interface
Pin name Pin number Default function Second function Default state
GPIO1/ KBR4 40 GPIO1 KBR4 Output, pull down
GPIO2/ KBR3 41 GPIO2 KBR3 Output, pull down
GPIO3/ KBR2 42 GPIO3 KBR2 Output, pull down
GPIO4/ KBR1 43 GPIO4 KBR1 Output, pull down
GPIO5/ KBR0 44 GPIO5 KBR0 Output, pull down
GPIO6/ KBC4 47 GPIO6 KBC4 Output, pull down
GPIO7/ KBC3 48 GPIO7 KBC3 Output, pull down
GPIO8/ KBC2 49 GPIO8 KBC2 Output, pull down
GPIO9/ KBC1 50 GPIO9 KBC1 Output, pull down
GPIO10 51 GPIO10 Output, pull down
GPIO11 67 GPIO11 Output, pull down
GPIO12 68 GPIO12 Output, pull down
4.14 External Reset
The external NRESET pin is used to reset the module. This function is used as an emergency reset only when AT
command “AT+CPOWD=1” and the PWRKEY pin have no effect. The NRESET pin could be pulled down to
reset the module. The reset timing is illustrated in the following figure.
Figure 35: Reset timing
This pin is already pulled up in the module, so the external pull-up resistor is not necessary. A 100nF capacitor
close to the NRESET pin is strongly recommended. A reference circuit is shown in the following figure.
SIM900R_Hardware Design_V1.00 34 2012-07-20