AP_BattMonitor: Maxell support temperature

libraries/AP_BattMonitor/AP_BattMonitor_SMBus_Maxell.cpp

@@ -10,12 +10,13 @@ extern const AP_HAL::HAL& hal;
 #include <AP_HAL/AP_HAL.h>
 
 
+#define BATTMONITOR_SMBUS_MAXELL_TEMP       0x08    // temperature register
 #define BATTMONITOR_SMBUS_MAXELL_VOLTAGE    0x09    // voltage register
 #define BATTMONITOR_SMBUS_MAXELL_CURRENT    0x0a    // current register
 #define BATTMONITOR_SMBUS_MAXELL_SPECIFICATION_INFO    0x1a    // specification info
 #define BATTMONITOR_SMBUS_MAXELL_MANUFACTURE_NAME  0x20    // manufacturer name
 
-#define BATTMONITOR_SMBUS_MAXELL_CELL_VOLTAGES 6
+#define BATTMONITOR_SMBUS_MAXELL_NUM_CELLS 6
 uint8_t maxell_cell_ids[] = { 0x3f,  // cell 1
                               0x3e,  // cell 2
                               0x3d,  // cell 3
@@ -29,7 +30,6 @@ uint8_t maxell_cell_ids[] = { 0x3f,  // cell 1
 
 /*
  * Other potentially useful registers, listed here for future use
- * #define BATTMONITOR_SMBUS_MAXELL_TEMP      0x08    // temperature register
  * #define BATTMONITOR_SMBUS_MAXELL_CHARGE_STATUS         0x0d    // relative state of charge
  * #define BATTMONITOR_SMBUS_MAXELL_BATTERY_STATUS        0x16    // battery status register including alarms
  * #define BATTMONITOR_SMBUS_MAXELL_BATTERY_CYCLE_COUNT   0x17    // cycle count
@@ -76,7 +76,8 @@ void AP_BattMonitor_SMBus_Maxell::timer()
         _state.healthy = true;
     }
 
-    for (uint8_t i = 0; i < BATTMONITOR_SMBUS_MAXELL_CELL_VOLTAGES; i++) {
+    // read cell voltages
+    for (uint8_t i = 0; i < BATTMONITOR_SMBUS_MAXELL_NUM_CELLS; i++) {
         if (read_word(maxell_cell_ids[i], data)) {
             _state.cell_voltages.cells[i] = data;
         } else {
@@ -95,6 +96,12 @@ void AP_BattMonitor_SMBus_Maxell::timer()
         _state.current_amps = -(float)((int16_t)data) / 1000.0f;
         _state.last_time_micros = tnow;
     }
+
+    // read temperature
+    if (read_word(BATTMONITOR_SMBUS_MAXELL_TEMP, data)) {
+        _state.temperature_time = AP_HAL::millis();
+        _state.temperature = ((float)(data - 2731) * 0.1f);
+    }
 }
 
 // read word from register