AP_BattMonitor: added option to send resting voltage to GCS

libraries/AP_BattMonitor/AP_BattMonitor.cpp

@@ -438,6 +438,19 @@ float AP_BattMonitor::voltage_resting_estimate(uint8_t instance) const
     }
 }
 
+/// voltage - returns battery voltage in volts for GCS, may be resting voltage if option enabled
+float AP_BattMonitor::gcs_voltage(uint8_t instance) const
+{
+    if ((_params[instance]._options.get() & uint32_t(AP_BattMonitor_Params::Options::GCS_Resting_Voltage)) != 0) {
+        return voltage_resting_estimate(instance);
+    }
+    if (instance < _num_instances) {
+        return state[instance].voltage;
+    } else {
+        return 0.0f;
+    }
+}
+
 /// current_amps - returns the instantaneous current draw in amperes
 bool AP_BattMonitor::current_amps(float &current, uint8_t instance) const {
     if ((instance < _num_instances) && (drivers[instance] != nullptr) && drivers[instance]->has_current()) {

libraries/AP_BattMonitor/AP_BattMonitor.h

@@ -162,6 +162,10 @@ public:
     float voltage(uint8_t instance) const;
     float voltage() const { return voltage(AP_BATT_PRIMARY_INSTANCE); }
 
+    // voltage for a GCS, may be resistance compensated
+    float gcs_voltage(uint8_t instance) const;
+    float gcs_voltage(void) const { return gcs_voltage(AP_BATT_PRIMARY_INSTANCE); }
+
     /// get voltage with sag removed (based on battery current draw and resistance)
     /// this will always be greater than or equal to the raw voltage
     float voltage_resting_estimate(uint8_t instance) const;

libraries/AP_BattMonitor/AP_BattMonitor_Params.cpp

@@ -143,7 +143,7 @@ const AP_Param::GroupInfo AP_BattMonitor_Params::var_info[] = {
     // @Param: OPTIONS
     // @DisplayName: Battery monitor options
     // @Description: This sets options to change the behaviour of the battery monitor
-    // @Bitmask: 0:Ignore DroneCAN SoC, 1:MPPT reports input voltage and current, 2:MPPT Powered off when disarmed, 3:MPPT Powered on when armed, 4:MPPT Powered off at boot, 5:MPPT Powered on at boot
+    // @Bitmask: 0:Ignore DroneCAN SoC, 1:MPPT reports input voltage and current, 2:MPPT Powered off when disarmed, 3:MPPT Powered on when armed, 4:MPPT Powered off at boot, 5:MPPT Powered on at boot, 6:Send resistance compensated voltage to GCS
     // @User: Advanced
     AP_GROUPINFO("OPTIONS", 21, AP_BattMonitor_Params, _options, 0),
 

libraries/AP_BattMonitor/AP_BattMonitor_Params.h

@@ -24,6 +24,7 @@ public:
         MPPT_Power_On_At_Arm                = (1U<<3),  // MPPT Enabled when vehicle is armed, if HW supports it
         MPPT_Power_Off_At_Boot              = (1U<<4),  // MPPT Disabled at startup (aka boot), if HW supports it
         MPPT_Power_On_At_Boot               = (1U<<5),  // MPPT Enabled at startup (aka boot), if HW supports it. If Power_Off_at_Boot is also set, the behavior is Power_Off_at_Boot
+        GCS_Resting_Voltage                 = (1U<<6),  // send resistance resting voltage to GCS
     };
 
     BattMonitor_LowVoltage_Source failsafe_voltage_source(void) const { return (enum BattMonitor_LowVoltage_Source)_failsafe_voltage_source.get(); }