hardware design v1.00
Table Of Contents
- Contents
- Version History
- 1 Introduction
- 2 SIM968 Overview
- 3 Package Information
- 4 GSM Application Interface
- 4.1 GSM Power Supply
- 4.2 Power on/down Scenarios
- 4.3 Power Saving Mode
- 4.4 Charging Interface
- 4.5 RTC Backup
- 4.6 Serial Interfaces
- 4.7 Audio Interfaces
- 4.8 SIM Card Interface
- 4.9 LCD Display/SPI Interface
- 4.10 Keypad Interface
- 4.11 ADC
- 4.12 RI Behaviors
- 4.13 Network Status Indication
- 4.14 General Purpose Input/Output (GPIO)
- 4.15 External Reset
- 4.16 PWM
- 4.17 I2C Bus
- 4.18 GSM Antenna Interface
- 5 GNSS Application Interface
- 6 Electrical, Reliability and Radio Characteristics
- 6.1 Absolute Maximum Ratings
- 6.2 Recommended Operating Conditions
- 6.3 Digital Interface Characteristics
- 6.4 SIM Card Interface Characteristics
- 6.5 VDD_EXT Characteristics
- 6.6 SIM_VDD Characteristics
- 6.7 VRTC Characteristics
- 6.8 Current Consumption (VBAT = 3.8V)
- 6.9 Electro-Static Discharge
- 6.10 Radio Characteristics
- 6.11 Module label information
- Appendix
Smart Machine Smart Decision
Figure 40: Internal supply Antenna bias voltage
Figure 41: External supply Antenna bias voltage
5.2 UART Interface
SIM968 GNSS engine includes two UARTS (UART and UART1) interface for serial communication. The UART
is as NMEA output and PMTK command input. The receiver (GPS_RXD) and transmitter (GPS_TXD) side of
every port contains a 16-byte FIFO and has 256 bytes URAM. The baud rates are selectable and ranging from 4.8
to 921.6kbps through CoreBuilder tool. UART can provide the developers signal or message outputs.
UART1 is as RTCM input.
For details about CoreBuilder information, please refer to document [21]
5.3 1PPS Output
The 1PPS pin outputs pulse-per-second (1PPS) pulse signal for precise timing purposes. It will come out after
successfully positioning .The 1PPS signal can be provided through designated output pin for many external
applications.
5.4 A-GPS
A-GPS is the meaning of Assisted GPS, which is a system that can improve the startup performance, and
time-to-first-fix (TTFF) of a GPS satellite-based positioning under certain conditions . SIM928 module supports
EPO file, and SBAS/RTCM.
5.4.1
EPO
The SIM968 supports the EPO (Extended Prediction Orbit) data service. The EPO data service is supporting
7/14/30-day orbit predictions to customers. It needs occasional download from EPO server. Supply of aiding
information like ephemeris, almanac, rough last position and time and satellite status and an optional time
synchronization signal will reduce time to first fix significantly and improve the acquisition sensitivity.
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