AP_UAVCAN: use const unique id length variable

libraries/AP_UAVCAN/AP_UAVCAN.cpp

@@ -180,15 +180,12 @@ void AP_UAVCAN::init(uint8_t driver_index)
     hw_version.major = AP_UAVCAN_HW_VERS_MAJOR;
     hw_version.minor = AP_UAVCAN_HW_VERS_MINOR;
 
-    uint8_t len = hw_version.unique_id.capacity();
-    uint8_t *unique_id = new uint8_t[len];
+    const uint8_t uid_buf_len = hw_version.unique_id.capacity();
+    uint8_t uid_len = uid_buf_len;
+    uint8_t unique_id[uid_buf_len];
 
-    if (unique_id) {
-        hal.util->get_system_id_unformatted(unique_id, len);
-        uavcan::copy(unique_id, unique_id + len, hw_version.unique_id.begin());
-    } else {
-        AP_HAL::panic("UAVCAN: Failed to allocate Unique ID");
-    }
+    if (hal.util->get_system_id_unformatted(unique_id, uid_len)) {
+        uavcan::copy(unique_id, unique_id + uid_len, hw_version.unique_id.begin());
 
         _node->setHardwareVersion(hw_version);
 
@@ -202,6 +199,7 @@ void AP_UAVCAN::init(uint8_t driver_index)
 #ifdef HAS_UAVCAN_SERVERS
         _servers.init(*_node);
 #endif
+    }
     // Roundup all subscribers from supported drivers
     AP_GPS_UAVCAN::subscribe_msgs(this);
     AP_Compass_UAVCAN::subscribe_msgs(this);

libraries/AP_UAVCAN/AP_UAVCAN_Servers.cpp

@@ -83,13 +83,7 @@ class AP_UAVCAN_FileEventTracer : public uavcan::dynamic_node_id_server::IEventT
 protected:
     virtual void onEvent(uavcan::dynamic_node_id_server::TraceCode code, uavcan::int64_t argument)
     {
-        struct log_UAVCAN_EVT pkt = {
-            LOG_PACKET_HEADER_INIT(LOG_UAVCAN_EVT_MSG),
-            time_us    : AP_HAL::micros64(),
-            code       : code,
-            argument   : argument
-        };
-        DataFlash_Class::instance()->WriteBlock(&pkt, sizeof(pkt));
+        DataFlash_Class::instance()->Log_Write("UCEV", "TimeUS,code,arg", "s--", "F--", "Qhq", AP_HAL::micros64(), code, argument);
     }
 };