add simulated gnss utc timestamp

src/uavcan_communicator/converters.cpp

@@ -18,6 +18,7 @@
 
 #include "converters.hpp"
 #include <algorithm>
+#include <chrono>
 
 float clamp_float(float value, float min, float max) {
     if (value < min) {
@@ -126,8 +127,20 @@ void DiffPressureRosToUavcan::ros_callback(IN_ROS_MSG_PTR in_ros_msg) {
     broadcast();
 }
 
+// Simulate GNSS timestamp by wrapping the time to align with a typical GNSS time reference (e.g., GPS epoch).
+// GPS epoch started on January 6, 1980, so we calculate the time since then.
+uint64_t simulate_gnss_utc_timestamp_usec() {
+    auto now = std::chrono::system_clock::now();
+    auto duration_since_epoch = std::chrono::duration_cast<std::chrono::microseconds>(now.time_since_epoch());
+    constexpr uint64_t gps_epoch_offset_usec = 315964800000000ULL;
+    uint64_t gnss_utc_timestamp_usec = duration_since_epoch.count() - gps_epoch_offset_usec;
+    return gnss_utc_timestamp_usec;
+}
 
 void GpsRosToUavcan::ros_callback(IN_ROS_MSG_PTR in_ros_msg) {
+    out_uavcan_msg_.gnss_timestamp.usec = simulate_gnss_utc_timestamp_usec();
+    out_uavcan_msg_.gnss_time_standard = 2;  // 2 stands for UTC
+
     out_uavcan_msg_.latitude_deg_1e8 = in_ros_msg->latitude * 1e8;
     out_uavcan_msg_.longitude_deg_1e8 = in_ros_msg->longitude * 1e8;
     out_uavcan_msg_.height_msl_mm = in_ros_msg->altitude * 1e3;