[dc] add option to send DC commands other an extra uart link

this can be used to synchronize DC commands from the autopilot and
external processing with companion board

sw/airborne/modules/digital_cam/atmega_i2c_cam_ctrl.c

@@ -41,6 +41,9 @@
 void dc_send_command(uint8_t cmd)
 {
   atmega_i2c_cam_ctrl_send(cmd);
+
+  // call command send_command function
+  dc_send_command_common(cmd);
 }
 
 static struct i2c_transaction atmega_i2c_cam_ctrl_trans;

sw/airborne/modules/digital_cam/dc.c

@@ -53,6 +53,11 @@
 #define DC_AUTOSHOOT_DISTANCE_INTERVAL 50
 #endif
 
+/** default distance of the first shoot: 0m (start immediately) */
+#ifndef DC_AUTOSHOOT_DISTANCE_INIT
+#define DC_AUTOSHOOT_DISTANCE_INIT 0
+#endif
+
 /** default distance interval for survey mode: 50m */
 #ifndef DC_AUTOSHOOT_SURVEY_INTERVAL
 #define DC_AUTOSHOOT_SURVEY_INTERVAL 50
@@ -181,6 +186,15 @@ uint8_t dc_info(void)
   return 0;
 }
 
+void dc_send_command_common(uint8_t cmd __attribute__((unused)))
+{
+#if DC_SHOT_EXTRA_DL
+  uint8_t tab[] = { cmd };
+  DOWNLINK_SEND_PAYLOAD_COMMAND(extra_pprz_tp, EXTRA_DOWNLINK_DEVICE, 0, 1, tab);
+#endif
+}
+
+
 /* shoot on distance */
 uint8_t dc_distance(float interval)
 {
@@ -234,7 +248,7 @@ uint8_t dc_survey(float interval, float x, float y)
     dc_gps_x = x;
     dc_gps_y = y;
   }
-  dc_gps_next_dist = 0;
+  dc_gps_next_dist = DC_AUTOSHOOT_DISTANCE_INIT;
   dc_info();
   return 0;
 }

sw/airborne/modules/digital_cam/dc.h

@@ -120,6 +120,9 @@ typedef enum {
 /** Send Command To Camera */
 extern void dc_send_command(uint8_t cmd);
 
+/** Command sending function */
+extern void dc_send_command_common(uint8_t cmd);
+
 /** Auotmatic Digital Camera Photo Triggering modes */
 typedef enum {
   DC_AUTOSHOOT_STOP = 0,

sw/airborne/modules/digital_cam/dc_ctrl_parrot_mykonos.c

@@ -198,6 +198,9 @@ void dc_send_command(uint8_t cmd)
     default:
       break;
 	}
+
+  // call command send_command function
+  dc_send_command_common(cmd);
 }
 #endif
 

sw/airborne/modules/digital_cam/gpio_cam_ctrl.c

@@ -165,4 +165,7 @@ void dc_send_command(uint8_t cmd)
     default:
       break;
   }
+
+  // call command send_command function
+  dc_send_command_common(cmd);
 }

sw/airborne/modules/digital_cam/servo_cam_ctrl.c

@@ -122,5 +122,8 @@ void dc_send_command(uint8_t cmd)
     default:
       break;
   }
+
+  // call command send_command function
+  dc_send_command_common(cmd);
 }
 

sw/airborne/modules/digital_cam/uart_cam_ctrl.c

@@ -174,4 +174,7 @@ void dc_send_command(uint8_t cmd)
     default:
       break;
   }
+
+  // call command send_command function
+  dc_send_command_common(cmd);
 }

sw/airborne/modules/digital_cam/video_cam_ctrl.c

@@ -67,4 +67,7 @@ void dc_send_command(uint8_t cmd)
     default:
       break;
   }
+
+  // call command send_command function
+  dc_send_command_common(cmd);
 }