batt_smbus add complementary filter and small fixes (#9080)

* Batt_smbus. Added complementary filter to remaining capacity, reversed warning state checks, and added remaining/discharged out of range checks to handle bad battery calibrations

* Changed errx to PX4_ERR

* Added PX4_ERR returns

src/drivers/batt_smbus/batt_smbus.cpp

@@ -541,38 +541,50 @@ BATT_SMBUS::cycle()
 		}
 
 		// read remaining capacity
-		if (_batt_capacity > 0) {
-			if (read_reg(BATT_SMBUS_REMAINING_CAPACITY, tmp) == OK) {
+		if (read_reg(BATT_SMBUS_REMAINING_CAPACITY, tmp) == OK) {
 
-				if (tmp > _batt_capacity) {
-					PX4_WARN("Remaining Cap greater than total: Cap:%hu RemainingCap:%hu", (uint16_t)_batt_capacity, (uint16_t)tmp);
-					_batt_capacity = (uint16_t)tmp;
-				}
+			if (tmp > _batt_capacity) {
+				PX4_WARN("Remaining Cap greater than total: Cap:%hu RemainingCap:%hu", (uint16_t)_batt_capacity, (uint16_t)tmp);
+				_batt_capacity = (uint16_t)tmp;
+			}
 
-				new_report.remaining = (float)(1.000f - (((float)_batt_capacity - (float)tmp) / (float)_batt_capacity));
+			// Calculate remaining capacity percent with complementary filter
+			new_report.remaining = (float)(_last_report.remaining * 0.8f) + (float)(0.2f * (float)(1.000f - (((
+						       float)_batt_capacity - (float)tmp) / (float)_batt_capacity)));
 
-				// calculate total discharged amount
-				new_report.discharged_mah = (float)((float)_batt_startup_capacity - (float)tmp);
-			}
+			// calculate total discharged amount
+			new_report.discharged_mah = (float)((float)_batt_startup_capacity - (float)tmp);
 		}
 
 		// read battery temperature and covert to Celsius
 		if (read_reg(BATT_SMBUS_TEMP, tmp) == OK) {
 			new_report.temperature = (float)(((float)tmp / 10.0f) - 273.15f);
 		}
 
-		// propagate warning state only if the state
-		if (new_report.remaining < _emergency_thr) {
+		//Check if remaining % is out of range
+		if ((new_report.remaining > 1.00f) || (new_report.remaining <= 0.00f)) {
+			new_report.warning = battery_status_s::BATTERY_WARNING_EMERGENCY;
+		}
+
+		//Check if discharged amount is greater than the starting capacity
+		else if (new_report.discharged_mah > (float)_batt_startup_capacity) {
 			new_report.warning = battery_status_s::BATTERY_WARNING_EMERGENCY;
+		}
 
-		} else if (new_report.remaining < _crit_thr) {
-			new_report.warning = battery_status_s::BATTERY_WARNING_CRITICAL;
+		// propagate warning state
+		else {
+			if (new_report.remaining > _low_thr) {
+				new_report.warning = battery_status_s::BATTERY_WARNING_NONE;
 
-		} else if (new_report.remaining < _low_thr) {
-			new_report.warning = battery_status_s::BATTERY_WARNING_LOW;
+			} else if (new_report.remaining > _crit_thr) {
+				new_report.warning = battery_status_s::BATTERY_WARNING_LOW;
 
-		} else {
-			new_report.warning = battery_status_s::BATTERY_WARNING_NONE;
+			} else if (new_report.remaining > _emergency_thr) {
+				new_report.warning = battery_status_s::BATTERY_WARNING_CRITICAL;
+
+			} else {
+				new_report.warning = battery_status_s::BATTERY_WARNING_EMERGENCY;
+			}
 		}
 
 		new_report.capacity = _batt_capacity;