Mavlink: fixed temperature for batteries (#12605)

msg/battery_status.msg

@@ -7,7 +7,7 @@ float32 average_current_a		# Battery current average in amperes, -1 if unknown
 float32 discharged_mah		# Discharged amount in mAh, -1 if unknown
 float32 remaining		# From 1 to 0, -1 if unknown
 float32 scale		# Power scaling factor, >= 1, or -1 if unknown
-float32 temperature         # temperature of the battery
+float32 temperature         # temperature of the battery. NaN if unknown
 int32 cell_count		# Number of cells
 bool connected			# Whether or not a battery is connected, based on a voltage threshold
 bool system_source		# Whether or not a this battery is the active power source for VDD_5V_IN

src/lib/battery/battery.cpp

@@ -97,6 +97,8 @@ Battery::updateBatteryStatus(hrt_abstime timestamp, float voltage_v, float curre
 		battery_status->system_source = selected_source;
 		battery_status->priority = priority;
 	}
+
+	battery_status->temperature = NAN;
 }
 
 void

src/modules/mavlink/mavlink_messages.cpp

@@ -52,6 +52,7 @@
 #include <lib/matrix/matrix/math.hpp>
 #include <px4_time.h>
 #include <systemlib/mavlink_log.h>
+#include <math.h>
 
 #include <uORB/topics/actuator_armed.h>
 #include <uORB/topics/actuator_controls.h>
@@ -704,7 +705,10 @@ protected:
 				bat_msg.energy_consumed = -1;
 				bat_msg.current_battery = (battery_status.connected) ? battery_status.current_filtered_a * 100 : -1;
 				bat_msg.battery_remaining = (battery_status.connected) ? ceilf(battery_status.remaining * 100.0f) : -1;
-				bat_msg.temperature = (battery_status.connected) ? (int16_t)battery_status.temperature : INT16_MAX;
+
+
+				bool temperature_valid = battery_status.connected && PX4_ISFINITE(battery_status.temperature);
+				bat_msg.temperature = temperature_valid ? (int16_t)(battery_status.temperature * 100.0f) : INT16_MAX;
 				//bat_msg.average_current_battery = (battery_status.connected) ? battery_status.average_current_a * 100.0f : -1;
 				//bat_msg.serial_number = (battery_status.connected) ? battery_status.serial_number : 0;
 				//bat_msg.capacity = (battery_status.connected) ? battery_status.capacity : 0;