Smart Machine Smart Decision
SIM868_Series_Hardware_Design_V1.06
50
2017-07-13
V
OH
2.4
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6.6.
Software Upgrade of GNSS
GNSS firmware can be upgraded through UART interface.
GPS_TXD
Module(GNSS)
GPS_RXD
GND
GNSS_EN
TXD
RXD
GND
Serial Port
I/O Connector
2.8V
10K
Figure 46: Connection for software upgrading and debugging for GNSS
If customer upgrades GSM and GNSS part in all-in-one mode, the GNSS UART should be connected to GSM
UART2; GNSS_EN must be connected to GPIO1 of GSM part through 10K resistance. Thus customer could
upgrade the module through UART1 or USB port of GSM.
GPS_TXD
SIM868 Module
GPS_RXD
GNSS_EN
UART2_TXD
UART2_RXD
R1
0R
GPIO1
R2
0R
R3
10K
Figure 47: Connection for software upgrading in all-in-one Mode
Note: GNSS_EN must be connected to GPIO1 of GSM part
6.7.
1PPS Output
The 1PPS pin outputs pulse-per-second signal for precise timing purposes after the position has been fixed. The
1PPS 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.
Figure 48 is the typical application of the 1PPS function:
SIMCOM
CONFIDENTIAL
FILE
