SITL: Create a second voltage to monitor for battery voltages

libraries/AP_HAL_SITL/AnalogIn.cpp

@@ -46,6 +46,12 @@ float ADCSource::read_latest() {
     case 13:
         return _sitlState->voltage_pin_value;
 
+    case 14:
+        return _sitlState->current2_pin_value;
+
+    case 15:
+        return _sitlState->voltage2_pin_value;
+
     case ANALOG_INPUT_NONE:
     default:
         return 0.0f;

libraries/AP_HAL_SITL/SITL_State.cpp

@@ -464,6 +464,9 @@ void SITL_State::_simulator_servos(SITL::Aircraft::sitl_input &input)
     // assume 3DR power brick
     voltage_pin_value = ((voltage / 10.1f) / 5.0f) * 1024;
     current_pin_value = ((_current / 17.0f) / 5.0f) * 1024;
+    // fake battery2 as just a 25% gain on the first one
+    voltage2_pin_value = ((voltage * 0.25f / 10.1f) / 5.0f) * 1024;
+    current2_pin_value = ((_current * 0.25f / 17.0f) / 5.0f) * 1024;
 }
 
 void SITL_State::init(int argc, char * const argv[])

libraries/AP_HAL_SITL/SITL_State.h

@@ -67,6 +67,8 @@ public:
     uint16_t airspeed_2_pin_value; // pin 2
     uint16_t voltage_pin_value;  // pin 13
     uint16_t current_pin_value;  // pin 12
+    uint16_t voltage2_pin_value;  // pin 15
+    uint16_t current2_pin_value;  // pin 14
 
     // return TCP client address for uartC
     const char *get_client_address(void) const { return _client_address; }