PPS Signal

mohsenhaddadi

Hi guys can anybody help me with this situation :
I am using a PPS signal comes from my GPS device and have connected it to my livox Horizon's converter 2, but when I use livox viewer or other apps it says that NO PPS is available. I have checked the signal with oscilloscope and all the connections.

Livox Support

2.3 PPS
Due to the complexity of this usage, users are not recommended to use this synchronization method

Every time Livox LiDAR receives the rising edge of the PPS signal, it will set the point cloud time at the current moment to 0, and then restart timing until the next PPS pulse arrives. We can use this feature to realize the synchronization of the PPS pulse to the LiDAR time.

The following is the pseudo code to implement this process:

// PPS Time Synchronization
static uint64_t lidar_time_last;
static uint64_t lidar_time_real;

// 1. Read the PPS rising edge time, Unit is nanosecond.
uint64_t pps_time_ns = get_pps_rising_nsecond();
// 2. Read LiDAR point time, Unit is nanosecond.
uint64_t lidar_time = get_lidar_pack_time();
// 3. Update real time.
if (lidar_time < lidar_time_last)
{
    //LiDAR time jump indicates the generation of PPS rising edge.
    lidar_time_real = pps_time_ns + lidar_time%(1000000000);
}
else
{
    lidar_time_real += lidar_time - lidar_time_last;
}
//Update history
lidar_time_last = lidar_time;
Remarks:

Users need to obtain the time information of the rising edge of the PPS through other methods, corresponding to the get_pps_rising_nsecond() interface in the above code.

Livox Support

If you want to use GPS signal for synchronization, livox viewer cannot display whether the GPS signal is successful. The port of livox viewer should be the same as the GPS transmission port.