[New Feature] LED indicates position lock

Signed-off-by: Richard Eoin Meadows <richardeoin@gmail.com>

firmware/inc/gps.h

@@ -40,6 +40,8 @@ struct ubx_nav_posllh gps_get_nav_posllh();
 struct ubx_nav_sol gps_get_nav_sol();
 struct ubx_nav_timeutc gps_get_nav_timeutc();
 
+uint8_t gps_is_locked(void);
+
 void gps_init(void);
 void usart_loopback_test(void);
 

firmware/src/gps.c

@@ -315,6 +315,15 @@ struct ubx_nav_timeutc gps_get_nav_timeutc()
 {
   return ubx_nav_timeutc;
 }
+/**
+ * Returns if the GPS has a position lock
+ */
+uint8_t gps_is_locked(void)
+{
+  return (ubx_nav_sol.payload.gpsFix == 0x2) ||
+    (ubx_nav_sol.payload.gpsFix == 0x3) ||
+    (ubx_nav_sol.payload.gpsFix == 0x4);
+}
 
 /**
  * Verify that the uBlox 6 GPS receiver is set to the <1g airborne

firmware/src/main.c

@@ -236,11 +236,19 @@ int main(void)
 
     gps_update();		/* Request updates from the gps */
 
-    led_on();
+    if (gps_is_locked()) {
+      led_on();
+    } else {
+      led_off();
+    }
 
     gps_update_wait();		/* Wait for the gps update */
 
-    led_off();
+    if (gps_is_locked()) {
+      led_off();
+    } else {
+      led_on();
+    }
 
     /* Set the next packet */
     set_telemetry_string();