Plane: added RSSI_RANGE parameter

ArduPlane/Parameters.h

@@ -180,6 +180,7 @@ public:
         k_param_rssi_pin,
         k_param_battery_volt_pin,   // unused
         k_param_battery_curr_pin,   // unused - 169
+        k_param_rssi_range,
 
         //
         // 170: Radio settings
@@ -411,6 +412,7 @@ public:
     AP_Int8 flap_2_percent;
     AP_Int8 flap_2_speed;
     AP_Int8 rssi_pin;
+    AP_Float rssi_range;             // allows to set max voltage for rssi pin such as 5.0, 3.3 etc.     
     AP_Int8 inverted_flight_ch;             // 0=disabled, 1-8 is channel for inverted flight trigger
     AP_Int8 stick_mixing;
     AP_Float takeoff_throttle_min_speed;

ArduPlane/Parameters.pde

@@ -753,6 +753,14 @@ const AP_Param::Info var_info[] PROGMEM = {
     // @User: Standard
     GSCALAR(rssi_pin,            "RSSI_PIN",         -1),
 
+    // @Param: RSSI_RANGE
+    // @DisplayName: Receiver RSSI voltage range
+    // @Description: Receiver RSSI voltage range
+    // @Units: Volt
+    // @Values: 3.3:3.3V, 5.0:5V
+    // @User: Standard
+    GSCALAR(rssi_range,          "RSSI_RANGE",         5.0),
+
     // @Param: INVERTEDFLT_CH
     // @DisplayName: Inverted flight channel
     // @Description: A RC input channel number to enable inverted flight. If this is non-zero then the APM will monitor the correcponding RC input channel and will enable inverted flight when the channel goes above 1750.

ArduPlane/sensors.pde

@@ -83,12 +83,16 @@ static void read_battery(void)
 // RC_CHANNELS_SCALED message
 void read_receiver_rssi(void)
 {
-    rssi_analog_source->set_pin(g.rssi_pin);
-    float ret = rssi_analog_source->voltage_average() * 50;
-    receiver_rssi = constrain_int16(ret, 0, 255);
+    // avoid divide by zero
+    if (g.rssi_range <= 0) {
+        receiver_rssi = 0;
+    }else{
+        rssi_analog_source->set_pin(g.rssi_pin);
+        float ret = rssi_analog_source->voltage_average() * 255 / g.rssi_range;
+        receiver_rssi = constrain_int16(ret, 0, 255);
+    }
 }
 
-
 /*
   return current_loc.alt adjusted for ALT_OFFSET
   This is useful during long flights to account for barometer changes