battery-monitoring: allow disabling analog battery monitoring through BAT{i}_V_CHANNEL param

src/modules/battery_status/analog_battery.cpp

@@ -127,7 +127,10 @@ bool AnalogBattery::is_valid()
 
 int AnalogBattery::get_voltage_channel()
 {
-	if (_analog_params.v_channel >= 0) {
+	if (_analog_params.v_channel == V_CHANNEL_DISABLED) {
+		return -1;
+
+	} else if (_analog_params.v_channel >= 0) {
 		return _analog_params.v_channel;
 
 	} else {
@@ -135,6 +138,7 @@ int AnalogBattery::get_voltage_channel()
 	}
 }
 
+
 int AnalogBattery::get_current_channel()
 {
 	if (_analog_params.i_channel >= 0) {

src/modules/battery_status/analog_battery.h

@@ -94,6 +94,9 @@ protected:
 	virtual void updateParams() override;
 
 private:
+
+	static constexpr int V_CHANNEL_DISABLED = -2;
+
 	uORB::Subscription _vehicle_status_sub{ORB_ID(vehicle_status)};
 	uint8_t _arming_state{0};
 

src/modules/battery_status/module.yaml

@@ -41,7 +41,9 @@ parameters:
                 short: Battery ${i} Voltage ADC Channel
                 long: |
                     This parameter specifies the ADC channel used to monitor voltage of main power battery.
-                    A value of -1 means to use the board default.
+                    A value of -1 means to use the board default. A value of -2 disables analog monitoring.
+                    This is useful when the FMU supports both analog and digital voltage monitoring and you want
+                    to use digital monitoring exclusively.
 
             type: int32
             reboot_required: true