HAL_Linux: use set_imu_target_temp() API

libraries/AP_HAL_Linux/Heat.h

@@ -18,4 +18,5 @@
 class Linux::Heat {
 public:
     virtual void set_imu_temp(float current) { }
+    virtual void set_imu_target_temp(int8_t *target) { }
 };

libraries/AP_HAL_Linux/Heat_Pwm.cpp

@@ -33,11 +33,10 @@ extern const AP_HAL::HAL& hal;
 
 using namespace Linux;
 
-HeatPwm::HeatPwm(uint8_t pwm_num, float Kp, float Ki, uint32_t period_ns, float target) :
+HeatPwm::HeatPwm(uint8_t pwm_num, float Kp, float Ki, uint32_t period_ns) :
     _Kp(Kp),
     _Ki(Ki),
-    _period_ns(period_ns),
-    _target(target)
+    _period_ns(period_ns)
 {
     _pwm = new PWM_Sysfs_Bebop(pwm_num);
     _pwm->set_period(_period_ns);
@@ -49,12 +48,17 @@ void HeatPwm::set_imu_temp(float current)
 {
     float error, output;
 
+    if (_target == nullptr) {
+        // not configured
+        return;
+    }
+    
     if (AP_HAL::millis() - _last_temp_update < 5) {
         return;
     }
 
     /* minimal PI algo without dt */
-    error = _target - current;
+    error = ((float)*_target) - current;
     /* Don't accumulate errors if the integrated error is superior
      * to the max duty cycle(pwm_period)
      */
@@ -74,4 +78,9 @@ void HeatPwm::set_imu_temp(float current)
     _last_temp_update = AP_HAL::millis();
 }
 
+void HeatPwm::set_imu_target_temp(int8_t *target)
+{
+    _target = target;
+}
+
 #endif

libraries/AP_HAL_Linux/Heat_Pwm.h

@@ -22,8 +22,9 @@
 class Linux::HeatPwm : public Linux::Heat {
 public:
     HeatPwm(uint8_t pwm_num, float Kp, float Ki,
-            uint32_t period_ns, float target);
-    void set_imu_temp(float current)override;
+            uint32_t period_ns);
+    void set_imu_temp(float current) override;
+    void set_imu_target_temp(int8_t *target) override;
 
 private:
     PWM_Sysfs_Base *_pwm;
@@ -32,5 +33,5 @@ private:
     float _Ki;
     uint32_t _period_ns;
     float _sum_error;
-    float _target;
+    int8_t *_target = nullptr;
 };

libraries/AP_HAL_Linux/Util.cpp

@@ -31,10 +31,9 @@ void Util::init(int argc, char * const *argv) {
 #ifdef HAL_UTILS_HEAT
 #if HAL_UTILS_HEAT == HAL_LINUX_HEAT_PWM
     _heat = new Linux::HeatPwm(HAL_LINUX_HEAT_PWM_NUM,
-                            HAL_LINUX_HEAT_KP,
-                            HAL_LINUX_HEAT_KI,
-                            HAL_LINUX_HEAT_PERIOD_NS,
-                            HAL_LINUX_HEAT_TARGET_TEMP);
+                               HAL_LINUX_HEAT_KP,
+                               HAL_LINUX_HEAT_KI,
+                               HAL_LINUX_HEAT_PERIOD_NS);
 #else
     #error Unrecognized Heat
 #endif // #if
@@ -43,11 +42,18 @@ void Util::init(int argc, char * const *argv) {
 #endif // #ifdef
 }
 
+// set current IMU temperatue in degrees C
 void Util::set_imu_temp(float current)
 {
     _heat->set_imu_temp(current);
 }
 
+// set target IMU temperatue in degrees C
+void Util::set_imu_target_temp(int8_t *target)
+{
+    _heat->set_imu_target_temp(target);
+}
+
 /**
    return commandline arguments, if available
 */

libraries/AP_HAL_Linux/Util.h

@@ -46,7 +46,8 @@ public:
     void set_custom_terrain_directory(const char *_custom_terrain_directory) { custom_terrain_directory = _custom_terrain_directory; }
 
     bool is_chardev_node(const char *path);
-    void set_imu_temp(float current);
+    void set_imu_temp(float current) override;
+    void set_imu_target_temp(int8_t *target) override;
 
     uint32_t available_memory(void) override;