Copter: use ins.wait_for_sample() for main loop

this takes advantage of the INS specific method to wait for a sample

ArduCopter/ArduCopter.pde

@@ -953,16 +953,18 @@ static void perf_update(void)
 
 void loop()
 {
+    // wait for an INS sample
+    if (!ins.wait_for_sample(1000)) {
+        Log_Write_Error(ERROR_SUBSYSTEM_MAIN, ERROR_CODE_INS_DELAY);
+        return;
+    }
     uint32_t timer = micros();
 
-    // We want this to execute fast
-    // ----------------------------
-    if (ins.sample_available()) {
-
     // check loop time
     perf_info_check_loop_time(timer - fast_loopTimer);
 
-        G_Dt                            = (float)(timer - fast_loopTimer) / 1000000.f;                  // used by PI Loops
+    // used by PI Loops
+    G_Dt                    = (float)(timer - fast_loopTimer) / 1000000.f;
     fast_loopTimer          = timer;
 
     // for mainloop failure monitoring
@@ -982,11 +984,6 @@ void loop()
     // call until scheduler.tick() is called again
     uint32_t time_available = (timer + 10000) - micros();
     scheduler.run(time_available - 500);
-    }
-    if ((timer - fast_loopTimer) < 8500) {
-        // we have plenty of time - be friendly to multi-tasking OSes
-        hal.scheduler->delay(1);
-    }
 }
 
 

ArduCopter/defines.h

@@ -449,6 +449,8 @@ enum ap_message {
 #define ERROR_CODE_COMPASS_FAILED_TO_READ   2
 // subsystem specific error codes -- gps
 #define ERROR_CODE_GPS_GLITCH               2
+// subsystem specific error codes -- main
+#define ERROR_CODE_INS_DELAY                1