AP_HAL_SITL: ADC resolution configurable by define, default to 16 bit

libraries/AP_HAL_SITL/AnalogIn.cpp

@@ -5,6 +5,8 @@
 #include "AnalogIn.h"
 #include <stdint.h>
 
+#define VOLTAGE_TO_PIN_VALUE(_v) (constrain_float(_v * (SITL_ADC_MAX_PIN_VALUE/SITL_ADC_FULL_SCALE_VOLTAGE), 0, SITL_ADC_MAX_PIN_VALUE))
+
 using namespace HALSITL;
 
 extern const AP_HAL::HAL& hal;
@@ -19,38 +21,34 @@ float ADCSource::read_average() {
 }
 
 float ADCSource::voltage_average() {
-    return (5.0f/1023.0f) * read_average();
+    return voltage_latest();
 }
 
 float ADCSource::voltage_latest() {
-    return (5.0f/1023.0f) * read_latest();
-}
-
-float ADCSource::read_latest() {
     switch (_pin) {
     case ANALOG_INPUT_BOARD_VCC:
-        return 1023;
+        return SITL_ADC_MAX_PIN_VALUE;
 
     case 0:
-        return _sitlState->sonar_pin_value;
+        return _sitlState->sonar_pin_voltage;
 
     case 1:
-        return _sitlState->airspeed_pin_value[0];
+        return _sitlState->airspeed_pin_voltage[0];
     
     case 2:
-        return _sitlState->airspeed_pin_value[1];
+        return _sitlState->airspeed_pin_voltage[1];
 
     case 12:
-        return _sitlState->current_pin_value;
+        return _sitlState->current_pin_voltage;
 
     case 13:
-        return _sitlState->voltage_pin_value;
+        return _sitlState->voltage_pin_voltage;
 
     case 14:
-        return _sitlState->current2_pin_value;
+        return _sitlState->current2_pin_voltage;
 
     case 15:
-        return _sitlState->voltage2_pin_value;
+        return _sitlState->voltage2_pin_voltage;
 
     case ANALOG_INPUT_NONE:
     default:
@@ -58,6 +56,10 @@ float ADCSource::read_latest() {
     }
 }
 
+float ADCSource::read_latest() {
+    return VOLTAGE_TO_PIN_VALUE(voltage_latest());
+}
+
 bool ADCSource::set_pin(uint8_t pin) {
     _pin = pin;
     return true;

libraries/AP_HAL_SITL/AnalogIn.h

@@ -3,6 +3,9 @@
 #include <AP_HAL/AP_HAL.h>
 #include "AP_HAL_SITL_Namespace.h"
 
+#define SITL_ADC_RESOLUTION 16 // bits of resolution
+#define SITL_ADC_MAX_PIN_VALUE ((1<<SITL_ADC_RESOLUTION)-1)
+#define SITL_ADC_FULL_SCALE_VOLTAGE 5.0f
 #define SITL_INPUT_MAX_CHANNELS 12
 
 class HALSITL::ADCSource : public AP_HAL::AnalogSource {

libraries/AP_HAL_SITL/SITL_State.cpp

@@ -912,11 +912,11 @@ void SITL_State::_simulator_servos(struct sitl_input &input)
     }
 
     // assume 3DR power brick
-    voltage_pin_value = float_to_uint16(((voltage / 10.1f) / 5.0f) * 1024);
-    current_pin_value = float_to_uint16(((_current / 17.0f) / 5.0f) * 1024);
+    voltage_pin_voltage = (voltage / 10.1f);
+    current_pin_voltage = _current/17.0f;
     // fake battery2 as just a 25% gain on the first one
-    voltage2_pin_value = float_to_uint16(((voltage * 0.25f / 10.1f) / 5.0f) * 1024);
-    current2_pin_value = float_to_uint16(((_current * 0.25f / 17.0f) / 5.0f) * 1024);
+    voltage2_pin_voltage = voltage_pin_voltage * .25f;
+    current2_pin_voltage = current_pin_voltage * .25f;
 }
 
 void SITL_State::init(int argc, char * const argv[])

libraries/AP_HAL_SITL/SITL_State.h

@@ -96,12 +96,12 @@ public:
     }
     
     // simulated airspeed, sonar and battery monitor
-    uint16_t sonar_pin_value;    // pin 0
-    uint16_t airspeed_pin_value[AIRSPEED_MAX_SENSORS]; // pin 1
-    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
+    float sonar_pin_voltage;    // pin 0
+    float airspeed_pin_voltage[AIRSPEED_MAX_SENSORS]; // pin 1
+    float voltage_pin_voltage;  // pin 13
+    float current_pin_voltage;  // pin 12
+    float voltage2_pin_voltage;  // pin 15
+    float current2_pin_voltage;  // pin 14
 
     // paths for UART devices
     const char *_uart_path[9] {

libraries/AP_HAL_SITL/sitl_airspeed.cpp

@@ -20,6 +20,10 @@ extern const AP_HAL::HAL& hal;
 
 using namespace HALSITL;
 
+// scaling value taken from AP_Airspeed_analog.cpp
+#define VOLTS_TO_PASCAL 819
+#define PASCAL_TO_VOLTS(_p) (_p/VOLTS_TO_PASCAL)
+
 // return current scale factor that converts from equivalent to true airspeed
 // valid for altitudes up to 10km AMSL
 // assumes standard atmosphere lapse rate
@@ -78,8 +82,8 @@ void SITL_State::_update_airspeed(float true_airspeed)
         airspeed_raw = airspeed_pressure + arspd.offset;
 
         _sitl->state.airspeed_raw_pressure[i] = airspeed_pressure;
-
-        airspeed_pin_value[i] = MIN(0xFFFF, airspeed_raw / 4);
+        
+        airspeed_pin_voltage[i] = PASCAL_TO_VOLTS(airspeed_raw);
     }
 }
 

libraries/AP_HAL_SITL/sitl_rangefinder.cpp

@@ -51,7 +51,7 @@ float SITL_State::_sonar_pin_voltage() const
  */
 void SITL_State::_update_rangefinder()
 {
-    sonar_pin_value = 1023 * (_sonar_pin_voltage() / 5.0f);
+    sonar_pin_voltage = _sonar_pin_voltage();
 }
 
 #endif