SITL: added basic analogin implementation

libraries/AP_HAL_AVR_SITL/AnalogIn.cpp

@@ -13,18 +13,26 @@ using namespace AVR_SITL;
 extern const AP_HAL::HAL& hal;
 
 ADCSource::ADCSource(uint8_t pin, float prescale) :
+    _pin(pin),
     _prescale(prescale)
 {}
 
 float ADCSource::read_average() {
-	return 0;
+	return read_latest();
 }
 
 float ADCSource::read_latest() {
-	return 0;
+    switch (_pin) {
+    case ANALOG_INPUT_BOARD_VCC:
+        return 4900;
+    case ANALOG_INPUT_NONE:
+    default:
+        return 0.0;
+    }
 }
 
 void ADCSource::set_pin(uint8_t pin) {
+    _pin = pin;
 }
 
 SITLAnalogIn::SITLAnalogIn() {}
@@ -32,12 +40,12 @@ SITLAnalogIn::SITLAnalogIn() {}
 void SITLAnalogIn::init(void *ap_hal_scheduler) {
 }
 
-AP_HAL::AnalogSource* SITLAnalogIn::channel(int16_t n) {
-    return NULL;
+AP_HAL::AnalogSource* SITLAnalogIn::channel(int16_t pin) {
+    return channel(pin, 1.0);
 }
 
-AP_HAL::AnalogSource* SITLAnalogIn::channel(int16_t n, float prescale) {
-    return NULL;	
+AP_HAL::AnalogSource* SITLAnalogIn::channel(int16_t pin, float prescale) {
+    return new ADCSource(pin, prescale);	
 }
 
 #endif

libraries/AP_HAL_AVR_SITL/AnalogIn.h

@@ -21,6 +21,7 @@ public:
 
 private:
     /* prescale scales the raw measurments for read()*/
+    uint8_t _pin;
     const float _prescale;
 };
 

libraries/AP_HAL_AVR_SITL/HAL_AVR_SITL_Class.cpp

@@ -29,9 +29,9 @@ static SITLConsoleDriver consoleDriver;
 static SITL_State sitlState;
 static SITLRCInput  sitlRCInput(&sitlState);
 static SITLRCOutput sitlRCOutput(&sitlState);
+static SITLAnalogIn sitlAnalogIn;
 
 static Empty::EmptyGPIO emptyGPIO;
-static Empty::EmptyAnalogIn emptyAnalogIn;
 
 static SITLUARTDriver sitlUart0Driver(0, &sitlState);
 static SITLUARTDriver sitlUart1Driver(1, &sitlState);
@@ -44,7 +44,7 @@ HAL_AVR_SITL::HAL_AVR_SITL() :
         &sitlUart2Driver,  /* uartC */
         NULL, /* i2c */
         NULL, /* spi */
-        &emptyAnalogIn, /* analogin */
+        &sitlAnalogIn, /* analogin */
         &sitlEEPROMStorage, /* storage */
         &consoleDriver, /* console */
         &emptyGPIO, /* gpio */