AP_BattMonitor: get Mavlink charge state

libraries/AP_BattMonitor/AP_BattMonitor.cpp

@@ -588,6 +588,31 @@ bool AP_BattMonitor::reset_remaining_mask(uint16_t battery_mask, float percentag
     return ret;
 }
 
+// Returns the mavlink charge state. The following mavlink charge states are not used
+// MAV_BATTERY_CHARGE_STATE_EMERGENCY , MAV_BATTERY_CHARGE_STATE_FAILED
+// MAV_BATTERY_CHARGE_STATE_UNHEALTHY, MAV_BATTERY_CHARGE_STATE_CHARGING
+MAV_BATTERY_CHARGE_STATE AP_BattMonitor::get_mavlink_charge_state(const uint8_t instance) const 
+{
+    if (instance >= _num_instances) {
+        return MAV_BATTERY_CHARGE_STATE_UNDEFINED;
+    }
+
+    switch (state[instance].failsafe) {
+
+    case Failsafe::None:
+        return MAV_BATTERY_CHARGE_STATE_OK;
+
+    case Failsafe::Low:
+        return MAV_BATTERY_CHARGE_STATE_LOW;
+
+    case Failsafe::Critical:
+        return MAV_BATTERY_CHARGE_STATE_CRITICAL;
+    }
+
+    // Should not reach this
+    return MAV_BATTERY_CHARGE_STATE_UNDEFINED;
+}
+
 namespace AP {
 
 AP_BattMonitor &battery()

libraries/AP_BattMonitor/AP_BattMonitor.h

@@ -214,6 +214,9 @@ public:
     bool reset_remaining_mask(uint16_t battery_mask, float percentage);
     bool reset_remaining(uint8_t instance, float percentage) { return reset_remaining_mask(1U<<instance, percentage);}
 
+    // Returns mavlink charge state
+    MAV_BATTERY_CHARGE_STATE get_mavlink_charge_state(const uint8_t instance) const;
+
     static const struct AP_Param::GroupInfo var_info[];
 
 protected: