GCS_MAVLink: move telemetry_delayed up into base class

libraries/GCS_MAVLink/GCS.h

@@ -211,6 +211,10 @@ public:
     // return current packet overhead for a channel
     static uint8_t packet_overhead_chan(mavlink_channel_t chan);
 
+    // FIXME: move this to be private/protected once possible
+    bool telemetry_delayed(mavlink_channel_t chan);
+    virtual uint32_t telem_delay() const = 0;
+
 protected:
 
     bool            waypoint_receiving; // currently receiving

libraries/GCS_MAVLink/GCS_Common.cpp

@@ -1628,3 +1628,21 @@ float GCS_MAVLINK::adjust_rate_for_stream_trigger(enum streams stream_num)
 
     return 1.0f;
 }
+
+// are we still delaying telemetry to try to avoid Xbee bricking?
+bool GCS_MAVLINK::telemetry_delayed(mavlink_channel_t _chan)
+{
+    uint32_t tnow = AP_HAL::millis() >> 10;
+    if (tnow > telem_delay()) {
+        return false;
+    }
+    if (_chan == MAVLINK_COMM_0 && hal.gpio->usb_connected()) {
+        // this is USB telemetry, so won't be an Xbee
+        return false;
+    }
+    // we're either on the 2nd UART, or no USB cable is connected
+    // we need to delay telemetry by the TELEM_DELAY time
+    return true;
+}
+
+

libraries/GCS_MAVLink/examples/routing/routing.cpp

@@ -19,6 +19,8 @@ public:
 
 protected:
 
+    uint32_t telem_delay() const override { return 0; };
+
 private:
 
     void handleMessage(mavlink_message_t * msg) { }