AP_BattMonitor: SMBus: Read serial number

libraries/AP_BattMonitor/AP_BattMonitor.cpp

@@ -68,7 +68,11 @@ const AP_Param::GroupInfo AP_BattMonitor::var_info[] = {
     AP_GROUPINFO("_WATT_MAX", 9, AP_BattMonitor, _watt_max[0], AP_BATT_MAX_WATT_DEFAULT),
 #endif
 
-    // 10 is left for future expansion
+    // @Param: _SERIAL_NUM
+    // @DisplayName: Battery serial number
+    // @Description: Battery serial number, automatically filled in for SMBus batteries, otherwise will be -1
+    // @User: Advanced
+    AP_GROUPINFO("_SERIAL_NUM", 10, AP_BattMonitor, _serial_numbers[0], AP_BATT_SERIAL_NUMBER_DEFAULT),
 
 #if AP_BATT_MONITOR_MAX_INSTANCES > 1
     // @Param: 2_MONITOR
@@ -131,6 +135,12 @@ const AP_Param::GroupInfo AP_BattMonitor::var_info[] = {
     AP_GROUPINFO("2_WATT_MAX", 18, AP_BattMonitor, _watt_max[1], AP_BATT_MAX_WATT_DEFAULT),
 #endif
 
+    // @Param: 2_SERIAL_NUM
+    // @DisplayName: Battery serial number
+    // @Description: Battery serial number, automatically filled in for SMBus batteries, otherwise will be -1
+    // @User: Advanced
+    AP_GROUPINFO("2_SERIAL_NUM", 20, AP_BattMonitor, _serial_numbers[1], AP_BATT_SERIAL_NUMBER_DEFAULT),
+
 #endif // AP_BATT_MONITOR_MAX_INSTANCES > 1
 
     AP_GROUPEND

libraries/AP_BattMonitor/AP_BattMonitor.h

@@ -14,6 +14,7 @@
 #define AP_BATT_CAPACITY_DEFAULT            3300
 #define AP_BATT_LOW_VOLT_TIMEOUT_MS         10000   // low voltage of 10 seconds will cause battery_exhausted to return true
 #define AP_BATT_MAX_WATT_DEFAULT            0
+#define AP_BATT_SERIAL_NUMBER_DEFAULT       -1
 
 #define AP_BATT_MONITOR_TIMEOUT             5000
 
@@ -147,6 +148,7 @@ protected:
     AP_Float    _curr_amp_offset[AP_BATT_MONITOR_MAX_INSTANCES];    /// offset voltage that is subtracted from current pin before conversion to amps
     AP_Int32    _pack_capacity[AP_BATT_MONITOR_MAX_INSTANCES];      /// battery pack capacity less reserve in mAh
     AP_Int16    _watt_max[AP_BATT_MONITOR_MAX_INSTANCES];           /// max battery power allowed. Reduce max throttle to reduce current to satisfy this limit
+    AP_Int32    _serial_numbers[AP_BATT_MONITOR_MAX_INSTANCES];     /// battery serial number, automatically filled in on SMBus batteries
 
 private:
     BattMonitor_State state[AP_BATT_MONITOR_MAX_INSTANCES];

libraries/AP_BattMonitor/AP_BattMonitor_SMBus.cpp

@@ -3,6 +3,26 @@
 #define AP_BATTMONITOR_SMBUS_PEC_POLYNOME 0x07 // Polynome for CRC generation
 
 #define BATTMONITOR_SMBUS_TEMP 0x08   // temperature register
+#define BATTMONITOR_SMBUS_SERIAL 0x1C // serial number
+AP_BattMonitor_SMBus::AP_BattMonitor_SMBus(AP_BattMonitor &mon,
+                                           AP_BattMonitor::BattMonitor_State &mon_state,
+                                           AP_HAL::OwnPtr<AP_HAL::I2CDevice> dev)
+        : AP_BattMonitor_Backend(mon, mon_state),
+        _dev(std::move(dev))
+{
+    _mon._serial_numbers[_state.instance] = AP_BATT_SERIAL_NUMBER_DEFAULT;
+}
+
+/// read the battery_voltage and current, should be called at 10hz
+void AP_BattMonitor_SMBus::read(void)
+{
+    // nothing to be done here for actually interacting with the battery
+    // however we can use this to set any parameters that need to be set
+
+    if (_serial_number != _mon._serial_numbers[_state.instance]) {
+        _mon._serial_numbers[_state.instance].set_and_notify(_serial_number);
+    }
+}
 
 // reads the temperature word from the battery
 // returns true if the read was successful
@@ -18,6 +38,22 @@ bool AP_BattMonitor_SMBus::read_temp(void)
     return false;
 }
 
+// reads the serial number if it's not already known
+// returns true if the read was successful or the number was already known
+bool AP_BattMonitor_SMBus::read_serial_number(void) {
+    uint16_t data;
+
+    // don't recheck the serial number if we already have it
+    if (_serial_number != -1) {
+        return true;
+    } else if (read_word(BATTMONITOR_SMBUS_SERIAL, data)) {
+        _serial_number = data;
+        return true;
+    }
+
+    return false;
+}
+
 // read word from register
 // returns true if read was successful, false if failed
 bool AP_BattMonitor_SMBus::read_word(uint8_t reg, uint16_t& data) const

libraries/AP_BattMonitor/AP_BattMonitor_SMBus.h

@@ -18,10 +18,7 @@ public:
     /// Constructor
     AP_BattMonitor_SMBus(AP_BattMonitor &mon, uint8_t instance,
                     AP_BattMonitor::BattMonitor_State &mon_state,
-                    AP_HAL::OwnPtr<AP_HAL::I2CDevice> dev)
-        : AP_BattMonitor_Backend(mon, instance, mon_state),
-          _dev(std::move(dev))
-    {}
+                    AP_HAL::OwnPtr<AP_HAL::I2CDevice> dev);
 
     // virtual destructor to reduce compiler warnings
     virtual ~AP_BattMonitor_SMBus() {}
@@ -29,10 +26,16 @@ public:
 
 protected:
 
+    void read(void) override;
+
     // reads the temperature word from the battery
     // returns true if the read was successful
     bool read_temp(void);
 
+    // reads the serial number if it's not already known
+    // returns true if the read was successful, or the number was already known
+    bool read_serial_number(void);
+
      // read word from register
      // returns true if read was successful, false if failed
     bool read_word(uint8_t reg, uint16_t& data) const;
@@ -44,6 +47,8 @@ protected:
     AP_HAL::OwnPtr<AP_HAL::I2CDevice> _dev;
     bool _pec_supported; // true if PEC is supported
 
+    int32_t _serial_number = -1;    // battery serial number
+
 };
 
 // include specific implementations

libraries/AP_BattMonitor/AP_BattMonitor_SMBus_Maxell.cpp

@@ -44,12 +44,6 @@ AP_BattMonitor_SMBus_Maxell::AP_BattMonitor_SMBus_Maxell(AP_BattMonitor &mon, ui
     _dev->register_periodic_callback(100000, FUNCTOR_BIND_MEMBER(&AP_BattMonitor_SMBus_Maxell::timer, void));
 }
 
-/// Read the battery voltage and current.  Should be called at 10hz
-void AP_BattMonitor_SMBus_Maxell::read()
-{
-    // nothing to do - all done in timer()
-}
-
 void AP_BattMonitor_SMBus_Maxell::timer()
 {
 	// check if PEC is supported
@@ -89,6 +83,8 @@ void AP_BattMonitor_SMBus_Maxell::timer()
     }
 
     read_temp();
+
+    read_serial_number();
 }
 
 // read_block - returns number of characters read if successful, zero if unsuccessful

libraries/AP_BattMonitor/AP_BattMonitor_SMBus_Maxell.h

@@ -15,9 +15,6 @@ public:
                              AP_BattMonitor::BattMonitor_State &mon_state,
                              AP_HAL::OwnPtr<AP_HAL::I2CDevice> dev);
 
-    // read does nothing, all done in timer
-    void read() override;
-
 private:
 
     void timer(void);

libraries/AP_BattMonitor/AP_BattMonitor_SMBus_Solo.cpp

@@ -38,12 +38,6 @@ AP_BattMonitor_SMBus_Solo::AP_BattMonitor_SMBus_Solo(AP_BattMonitor &mon, uint8_
     _dev->register_periodic_callback(100000, FUNCTOR_BIND_MEMBER(&AP_BattMonitor_SMBus_Solo::timer, void));
 }
 
-/// Read the battery voltage and current.  Should be called at 10hz
-void AP_BattMonitor_SMBus_Solo::read()
-{
-    // nothing to do - all done in timer()
-}
-
 void AP_BattMonitor_SMBus_Solo::timer()
 {
     uint16_t data;
@@ -118,6 +112,8 @@ void AP_BattMonitor_SMBus_Solo::timer()
     }
 
     read_temp();
+
+    read_serial_number();
 }
 
 // read_block - returns number of characters read if successful, zero if unsuccessful

libraries/AP_BattMonitor/AP_BattMonitor_SMBus_Solo.h

@@ -15,9 +15,6 @@ public:
                              AP_BattMonitor::BattMonitor_State &mon_state,
                              AP_HAL::OwnPtr<AP_HAL::I2CDevice> dev);
 
-    // read does nothing, all done in timer
-    void read() override;
-
 private:
 
     void timer(void);