APM: added RSSI_PIN option for receiver RSSI

this allows you to configure the pin for receiver RSSI without
recompiling

ArduPlane/ArduPlane.pde

@@ -274,9 +274,9 @@ AP_AnalogSource_ADC pitot_analog_source( &adc,
 AP_AnalogSource_Arduino pitot_analog_source(CONFIG_PITOT_SOURCE_ANALOG_PIN, 4.0);
 #endif
 
-#if RECEIVER_RSSI_PIN != -1
+// a pin for reading the receiver RSSI voltage. The scaling by 0.25 
-AP_AnalogSource_Arduino RSSI_pin(RECEIVER_RSSI_PIN, 0.25);
+// is to take the 0 to 1024 range down to an 8 bit range for MAVLink
-#endif
+AP_AnalogSource_Arduino RSSI_pin(-1, 0.25);
 
 AP_Relay relay;
 

ArduPlane/Parameters.h

@@ -138,7 +138,8 @@ public:
         //
         // Battery monitoring parameters
         //
-        k_param_battery_volt_pin = 168,
+        k_param_rssi_pin = 167,
+        k_param_battery_volt_pin,
         k_param_battery_curr_pin,   // 169
 
         //
@@ -341,6 +342,7 @@ public:
     AP_Float curr_amp_per_volt;
     AP_Float input_voltage;
     AP_Int32 pack_capacity;                     // Battery pack capacity less reserve
+    AP_Int8 rssi_pin;
     AP_Int8 battery_volt_pin;
     AP_Int8 battery_curr_pin;
     AP_Int8 inverted_flight_ch;             // 0=disabled, 1-8 is channel for inverted flight trigger

ArduPlane/Parameters.pde

@@ -534,16 +534,24 @@ const AP_Param::Info var_info[] PROGMEM = {
     // @Param: BATT_VOLT_PIN
     // @DisplayName: Battery Voltage sensing pin
     // @Description: Setting this to 0 ~ 13 will enable battery current sensing on pins A0 ~ A13.
-    // @Values: 99:Disabled, 0:A0, 1:A1, 13:A13
+    // @Values: -1:Disabled, 0:A0, 1:A1, 13:A13
     // @User: Standard
     GSCALAR(battery_volt_pin,    "BATT_VOLT_PIN",    BATTERY_VOLT_PIN),
 
     // @Param: BATT_CURR_PIN
     // @DisplayName: Battery Current sensing pin
     // @Description: Setting this to 0 ~ 13 will enable battery current sensing on pins A0 ~ A13.
-    // @Values: 99:Disabled, 1:A1, 2:A2, 12:A12
+    // @Values: -1:Disabled, 1:A1, 2:A2, 12:A12
     // @User: Standard
     GSCALAR(battery_curr_pin,    "BATT_CURR_PIN",    BATTERY_CURR_PIN),
+
+    // @Param: RSSI_PIN
+    // @DisplayName: Receiver RSSI sensing pin
+    // @Description: This selects an analog pin for the receiver RSSI voltage. It assumes the voltage is 5V for max rssi, 0V for minimum
+    // @Values: -1:Disabled, 0:A0, 1:A1, 13:A13
+    // @User: Standard
+    GSCALAR(rssi_pin,            "RSSI_PIN",         -1),
+
     GSCALAR(inverted_flight_ch,     "INVERTEDFLT_CH", 0),
 
     // barometer ground calibration. The GND_ prefix is chosen for

ArduPlane/config.h

@@ -134,11 +134,6 @@
 #endif
 
 
-// pin for receiver RSSI
-#ifndef RECEIVER_RSSI_PIN
-# define RECEIVER_RSSI_PIN -1
-#endif
-
 //////////////////////////////////////////////////////////////////////////////
 // IMU Selection
 //

ArduPlane/sensors.pde

@@ -64,10 +64,9 @@ static void read_battery(void)
 // RC_CHANNELS_SCALED message
 void read_receiver_rssi(void)
 {
-#if RECEIVER_RSSI_PIN != -1
+    RSSI_pin.set_pin(g.rssi_pin);
     float ret = RSSI_pin.read();
     receiver_rssi = constrain(ret, 0, 255);
-#endif
 }