Smart Machine Smart Decision
SIM68R_Hardware Design_V1.02
18
2013-01-22
Table 5: Host port multiplexed function pins
Pin name
Pin number
UART function
TXD
3
data transmit
RXD
4
data receive
4.3
I
2
C
interface
The SCL and SDA are the I
2
C bus pins, which can be connected to a
external
I
2
C
interface EEPROM up to
1
Mbits for reading and writing data into EEPROM. This can be used to store configurations permanently.
NOTE: The EEPROM can’t be supported currently.
4.4
Timemark Output
The Timemark pin outputs pulse-per-second (1PPS) pulse signal for precise timing purposes. It will come out
after successfully positioning .The Timemark signal can be provided through designated output pin for many
external applications. This pulse is not only limited to be active every second but also allowed to set the required
duration, frequency, and active high/low by programming user-defined settings.
4.5
DET_N
DET_N is an input pin and is used to report whether an external circuit has detected an external antenna or
not .Low level means the antenna has been detected. High level means no external antenna has been detected.
NOTE: The High level for DET_N should be 2.85V CMOS level.
4.6
A-GPS
A-GPS is the meaning of Assisted GPS, which is a system that can under certain conditions improve the startup
performance, or time-to-first-fix (TTFF) of a GPS satellite-based positioning system. SIM68R module supports
EPO file, EASY mode and SBAS/RTCM
4.6.1
EPO
The SIM68R 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.
The user should update the EPO files from the EPO server daily through the internet. Then the EPO data should
send to the SIM68R 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 [4] for more information