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
4.9 Keypad Interface
The keypad interface consists of 4 keypad column outputs and 5 keypad row inputs. The basic configuration is 4
keypad columns and 5 keypad rows, total 20 keys.
Table 10: Pin definition of the keypad interface
Pin name Pin number Default function Second function Default state
GPIO1/ KBR4 40
SIM900R_Hardware Design_V1.00 31 2012-07-20
The keypad interface allows a direct external matrix connection. A typical recommended circuit of the keypad is
shown in the following figure.
Figure 29: Reference circuit of the keypad interface
Note: This function is not supported in the standard firmware. If user wants this function, the firmware must be customized.
Please contact SIMCom for more details.
4.10 ADC
SIM900R 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].
GPIO1 Output, Pull down
GPIO2/ KBR3 41 GPIO2 Output, Pull down
GPIO3/ KBR2 42 GPIO3 Output, Pull down
GPIO4/ KBR1 43 GPIO4 Output, Pull down
GPIO5/ KBR0 44 GPIO5
Keypad matrix
column
Output, Pull down
GPIO6/ KBC4 47 GPIO6 Output, Pull down
GPIO7/ KBC3 48 GPIO7 Output, Pull down
GPIO8/ KBC2 49 GPIO8 Output, Pull down
Keypad matrix row
GPIO9/ KBC1
50 GPIO9 Output, Pull down