AP_BattMonitor: support EFI "battery" backend

this maps Ah to Litres and Amps to Litres/hour

libraries/AP_BattMonitor/AP_BattMonitor.cpp

@@ -13,6 +13,7 @@
 #include "AP_BattMonitor_FuelFlow.h"
 #include "AP_BattMonitor_FuelLevel_PWM.h"
 #include "AP_BattMonitor_Generator.h"
+#include "AP_BattMonitor_EFI.h"
 #include "AP_BattMonitor_INA2xx.h"
 #include "AP_BattMonitor_INA239.h"
 #include "AP_BattMonitor_LTC2946.h"
@@ -356,6 +357,11 @@ AP_BattMonitor::init()
                 drivers[instance] = new AP_BattMonitor_INA239(*this, state[instance], _params[instance]);
                 break;
 #endif
+#if HAL_EFI_ENABLED
+            case Type::EFI:
+                drivers[instance] = new AP_BattMonitor_EFI(*this, state[instance], _params[instance]);
+                break;
+#endif // HAL_EFI_ENABLED
             case Type::NONE:
             default:
                 break;

libraries/AP_BattMonitor/AP_BattMonitor.h

@@ -44,6 +44,7 @@ class AP_BattMonitor_INA239;
 class AP_BattMonitor_LTC2946;
 class AP_BattMonitor_Torqeedo;
 class AP_BattMonitor_FuelLevel_Analog;
+class AP_BattMonitor_EFI;
 
 
 class AP_BattMonitor
@@ -60,6 +61,7 @@ class AP_BattMonitor
     friend class AP_BattMonitor_FuelFlow;
     friend class AP_BattMonitor_FuelLevel_PWM;
     friend class AP_BattMonitor_Generator;
+    friend class AP_BattMonitor_EFI;
     friend class AP_BattMonitor_INA2XX;
     friend class AP_BattMonitor_INA239;
     friend class AP_BattMonitor_LTC2946;
@@ -104,6 +106,7 @@ public:
         FuelLevel_Analog               = 24,
         Analog_Volt_Synthetic_Current  = 25,
         INA239_SPI                     = 26,
+        EFI                            = 27,
     };
 
     FUNCTOR_TYPEDEF(battery_failsafe_handler_fn_t, void, const char *, const int8_t);

libraries/AP_BattMonitor/AP_BattMonitor_EFI.cpp

@@ -0,0 +1,55 @@
+/*
+   This program is free software: you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation, either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "AP_BattMonitor_EFI.h"
+
+#if HAL_EFI_ENABLED
+
+#include <AP_Common/AP_Common.h>
+#include <AP_Math/AP_Math.h>
+#include <AP_EFI/AP_EFI.h>
+
+extern const AP_HAL::HAL& hal;
+
+// update state
+void AP_BattMonitor_EFI::read()
+{
+    AP_EFI *efi = AP::EFI();
+    if (efi == nullptr) {
+        return;
+    }
+
+    if (!efi->is_healthy()) {
+        _state.healthy = false;
+        return;
+    }
+
+    struct EFI_State efi_state;
+    /*
+      a simple mapping of 1 Amp == 1 litre/hour and 1Ah = 1Litre
+     */
+    efi->get_state(efi_state);
+
+    _state.current_amps = efi_state.fuel_consumption_rate_cm3pm*0.001*60; // litres/hour
+    // use arbitrary 1.0 Volts
+    _state.voltage = 1.0;
+    _state.consumed_mah = efi_state.estimated_consumed_fuel_volume_cm3; // millilitres
+    _state.consumed_wh = 0.001 * _state.consumed_mah;
+    _state.healthy = true;
+    _state.last_time_micros = AP_HAL::micros();
+}
+
+#endif // HAL_EFI_ENABLED
+

libraries/AP_BattMonitor/AP_BattMonitor_EFI.h

@@ -0,0 +1,29 @@
+#pragma once
+
+#include <AP_EFI/AP_EFI_config.h>
+
+#if HAL_EFI_ENABLED
+
+#include "AP_BattMonitor.h"
+#include "AP_BattMonitor_Backend.h"
+
+class AP_BattMonitor_EFI : public AP_BattMonitor_Backend
+{
+public:
+
+    // Inherit constructor
+    using AP_BattMonitor_Backend::AP_BattMonitor_Backend;
+
+    // update state
+    void read(void) override;
+
+    bool has_current(void) const override {
+        return true;
+    }
+
+    bool has_consumed_energy(void) const override {
+        return true;
+    }
+};
+#endif // HAL_EFI_ENABLED
+

libraries/AP_BattMonitor/AP_BattMonitor_Params.cpp

@@ -13,7 +13,7 @@ const AP_Param::GroupInfo AP_BattMonitor_Params::var_info[] = {
     // @Param: MONITOR
     // @DisplayName: Battery monitoring
     // @Description: Controls enabling monitoring of the battery's voltage and current
-    // @Values: 0:Disabled,3:Analog Voltage Only,4:Analog Voltage and Current,5:Solo,6:Bebop,7:SMBus-Generic,8:DroneCAN-BatteryInfo,9:ESC,10:Sum Of Selected Monitors,11:FuelFlow,12:FuelLevelPWM,13:SMBUS-SUI3,14:SMBUS-SUI6,15:NeoDesign,16:SMBus-Maxell,17:Generator-Elec,18:Generator-Fuel,19:Rotoye,20:MPPT,21:INA2XX,22:LTC2946,23:Torqeedo,24:FuelLevelAnalog,25:Synthetic Current and Analog Voltage
+    // @Values: 0:Disabled,3:Analog Voltage Only,4:Analog Voltage and Current,5:Solo,6:Bebop,7:SMBus-Generic,8:DroneCAN-BatteryInfo,9:ESC,10:Sum Of Selected Monitors,11:FuelFlow,12:FuelLevelPWM,13:SMBUS-SUI3,14:SMBUS-SUI6,15:NeoDesign,16:SMBus-Maxell,17:Generator-Elec,18:Generator-Fuel,19:Rotoye,20:MPPT,21:INA2XX,22:LTC2946,23:Torqeedo,24:FuelLevelAnalog,25:Synthetic Current and Analog Voltage,26:INA239_SPI,27:EFI
     // @User: Standard
     // @RebootRequired: True
     AP_GROUPINFO_FLAGS("MONITOR", 1, AP_BattMonitor_Params, _type, int8_t(AP_BattMonitor::Type::NONE), AP_PARAM_FLAG_ENABLE),