RS-LiDAR-16 User Manual
6 GPS Synchronization
RS-LiDAR-16 supports external GPS receiver connections. With GPS connections, we can synchronize
the RS-LiDAR-16 system time and pack the GPRMC message into DIFOP packets.
6.1 GPS Synchronization Theory
The GPS receiver keeps generating synchronization Pulse Per Second (PPS) signal and GPRMC
message and send them to the sensor. The pulse width of the PPS should between 20ms to 200ms,
and the GPRMC message should be received within 500ms after the PPS signal is generated.
6.2 GPS Usage
There are two different level protocols for GPS_REC PINs:
3.3V TTL level standard and RS232 level standard respectively.
It can be distinguished by checking the firmware version which is shown in Appendix C RS-View of this
user manual, Figure C-14. If version No. begins with 08, it is TTL protocol. If version No. begins with 09,
it is RS232 protocol. The GPS interface on the Interface BOX is SH1.0-6P female connector, the PIN
definition is as shown in Figure 4. There are two main differences between the two protocols, which are
shown as below:
TTL level PIN definition: PIN GPS REC receives the data that is 3.3 V TTL standard from GPS module
serial port.
PIN GPS PULSE receives the PPS from GPS module.
RS232 PIN definition:
PIN GPS REC receives the data that is R232 level standard from the GPS module serial port;
PIN GPS PULSE receives the PPS from GPS module, and the level requirement is 3.0V~15.0V;
If the GPS output you are using is RS232 serial protocol while the level of the LiDAR receiver is TTL,
then you need to purchase a module which converts RS232 level to TTL level. For one example, the
wiring diagram and definition are in Figure 12 as follows:
Figure 12: RS232 to TTL Level Conversion Module.
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