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
SIM968_Hardware Design_V1.00 2013.02.25
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The user should update the EPO files from the EPO server daily through the internet. Then the EPO data should
send to the SIM968 by the HOST side. SIM68R has the short cold TTFF and warm TTFF, when the A-GPS is
used.
Note: For more information about EPO, please contact SIMCom sales. users can refer to document [20] for more information
5.4.2 EASY MODE
EASY is the abbreviation of Embedded Assist System, it works as embedded firmware which accelerates TTFF
by predicting satellite navigation messages from received ephemeris.
No additional computing interval for EASY task. EASY is efficiently scheduled and computed in free time of
every second after GNSS navigation solution.
EASY function is conceptually designed to automatically engage for predicting after first receiving the broadcast
ephemeris. After a while （generally tens of seconds）, 3-day extensions will be completely generated then all
EASY functions will be maintained at a sleep condition. EASY assistance is going to be engaged when the
GNSS requests in new TTFF condition or re-generates again with another new received ephemeris. Meanwhile,
TTFF will be benefited by EASY assistance.
Note: EASY function is default open and can be closed by PMTK command.
5.4.3 SBAS and RTCM
SBAS is the abbreviation of Satellite Based Augmentation System. The SBAS concept is based on the
transmission of differential corrections and integrity messages for navigation satellites that are within sight of a
network of reference stations deployed across an entire continent. SBAS messages are broadcast via geostationary
satellites able to cover vast areas.
Several countries have implemented their own satellite-based augmentation system. Europe has the European
Geostationary Navigation Overlay Service (EGNOS) which covers Western Europe and beyond. The USA has
its Wide Area Augmentation System (WAAS). Japan is covered by its Multi-functional Satellite Augmentation
System (MSAS). India has launched its own SBAS program named GNSS and GEO Augmented Navigation
(GAGAN) to cover the Indian subcontinent.
SIM968 module supports SBAS and RTCM, but only one mode can be applied at one time, and SBAS is the
default feature, customers who want to apply RTCM in the design can contact SIMCom sales for supporting
5.5 GNSS Antenna Interface
5.5.1 GNSS Antenna Interface
The RF interface has an impedance of 50Ω. To suit the physical design of individual applications, SIM968 offers
the interface as GPS_ANT pad.
The customer’s GNSS antenna can be located in the customer’s main board and connect to module’s GPS_ANT
pad through microstrip line or other type RF trace, which impendence must be controlled in 50Ω. The customer’s
main board under the GPS_ANT pad should be copper keep out. To minimize the loss on the PCB RF path, it