AP_Motors: add PWM_MIN, MAX

These parameters allow the motor PWM output range to be different from receiver's throttle input range
Also renamed throttle_pass_through to set_throttle_passthrough_for_esc_calibration and change the method's input to the 0 to 1 range instead of direct PWM value

libraries/AP_Motors/AP_MotorsCoax.cpp

@@ -122,8 +122,8 @@ void AP_MotorsCoax::output_to_motors()
             rc_write(AP_MOTORS_MOT_2, calc_pwm_output_1to1(_pitch_radio_passthrough, _servo2));
             rc_write(AP_MOTORS_MOT_3, calc_pwm_output_1to1(_roll_radio_passthrough, _servo3));
             rc_write(AP_MOTORS_MOT_4, calc_pwm_output_1to1(_pitch_radio_passthrough, _servo4));
-            rc_write(AP_MOTORS_MOT_5, _throttle_radio_min);
+            rc_write(AP_MOTORS_MOT_5, get_pwm_min());
-            rc_write(AP_MOTORS_MOT_6, _throttle_radio_min);
+            rc_write(AP_MOTORS_MOT_6, get_pwm_min());
             hal.rcout->push();
             break;
         case SPIN_WHEN_ARMED:
@@ -133,8 +133,8 @@ void AP_MotorsCoax::output_to_motors()
             rc_write(AP_MOTORS_MOT_2, calc_pwm_output_1to1(_throttle_low_end_pct * _actuator_out[1], _servo2));
             rc_write(AP_MOTORS_MOT_3, calc_pwm_output_1to1(_throttle_low_end_pct * _actuator_out[2], _servo3));
             rc_write(AP_MOTORS_MOT_4, calc_pwm_output_1to1(_throttle_low_end_pct * _actuator_out[3], _servo4));
-            rc_write(AP_MOTORS_MOT_5, constrain_int16(_throttle_radio_min + _throttle_low_end_pct * _min_throttle, _throttle_radio_min, _throttle_radio_min + _min_throttle));
+            rc_write(AP_MOTORS_MOT_5, constrain_int16(get_pwm_min() + _throttle_low_end_pct * _min_throttle, get_pwm_min(), get_pwm_min() + _min_throttle));
-            rc_write(AP_MOTORS_MOT_6, constrain_int16(_throttle_radio_min + _throttle_low_end_pct * _min_throttle, _throttle_radio_min, _throttle_radio_min + _min_throttle));
+            rc_write(AP_MOTORS_MOT_6, constrain_int16(get_pwm_min() + _throttle_low_end_pct * _min_throttle, get_pwm_min(), get_pwm_min() + _min_throttle));
             hal.rcout->push();
             break;
         case SPOOL_UP:

libraries/AP_Motors/AP_MotorsMatrix.cpp

@@ -94,7 +94,7 @@ void AP_MotorsMatrix::output_to_motors()
             // set motor output based on thrust requests
             for (i=0; i<AP_MOTORS_MAX_NUM_MOTORS; i++) {
                 if (motor_enabled[i]) {
-                    motor_out[i] = _throttle_radio_min;
+                    motor_out[i] = get_pwm_min();
                 }
             }
             break;
@@ -102,7 +102,7 @@ void AP_MotorsMatrix::output_to_motors()
             // sends output to motors when armed but not flying
             for (i=0; i<AP_MOTORS_MAX_NUM_MOTORS; i++) {
                 if (motor_enabled[i]) {
-                    motor_out[i] = constrain_int16(_throttle_radio_min + _throttle_low_end_pct * _min_throttle, _throttle_radio_min, _throttle_radio_min + _min_throttle);
+                    motor_out[i] = constrain_int16(get_pwm_min() + _throttle_low_end_pct * _min_throttle, get_pwm_min(), get_pwm_min() + _min_throttle);
                 }
             }
             break;

libraries/AP_Motors/AP_MotorsMulticopter.cpp

@@ -105,7 +105,21 @@ const AP_Param::GroupInfo AP_MotorsMulticopter::var_info[] = {
     // @Values: 0:Normal,1:OneShot,2:OneShot125
     // @User: Advanced
     AP_GROUPINFO("PWM_TYPE", 15, AP_MotorsMulticopter, _pwm_type, PWM_TYPE_NORMAL),
-    
+
+    // @Param: PWM_MIN
+    // @DisplayName: PWM output miniumum
+    // @Description: This sets the min PWM output value that will ever be output to the motors, 0 = use input RC3_MIN
+    // @Range: 0 2000
+    // @User: Advanced
+    AP_GROUPINFO("PWM_MIN", 16, AP_MotorsMulticopter, _pwm_min, 0),
+
+    // @Param: PWM_MAX
+    // @DisplayName: PWM output maximum
+    // @Description: This sets the max PWM value that will ever be output to the motors, 0 = use input RC3_MAX
+    // @Range: 0 2000
+    // @User: Advanced
+    AP_GROUPINFO("PWM_MAX", 17, AP_MotorsMulticopter, _pwm_max, 0),
+
     AP_GROUPEND
 };
 
@@ -114,10 +128,7 @@ AP_MotorsMulticopter::AP_MotorsMulticopter(uint16_t loop_rate, uint16_t speed_hz
     AP_Motors(loop_rate, speed_hz),
     _throttle_rpy_mix_desired(AP_MOTORS_THR_LOW_CMP_DEFAULT),
     _throttle_rpy_mix(AP_MOTORS_THR_LOW_CMP_DEFAULT),
-    _min_throttle(AP_MOTORS_DEFAULT_MIN_THROTTLE),
     _hover_out(AP_MOTORS_DEFAULT_MID_THROTTLE),
-    _throttle_radio_min(1100),
-    _throttle_radio_max(1900),
     _batt_voltage_resting(0.0f),
     _batt_current_resting(0.0f),
     _batt_resistance(0.0f),
@@ -133,6 +144,9 @@ AP_MotorsMulticopter::AP_MotorsMulticopter(uint16_t loop_rate, uint16_t speed_hz
     // setup battery voltage filtering
     _batt_voltage_filt.set_cutoff_frequency(AP_MOTORS_BATT_VOLT_FILT_HZ);
     _batt_voltage_filt.reset(1.0f);
+
+    // default throttle ranges (i.e. _min_throttle, _throttle_radio_min, _throttle_radio_max)
+    set_throttle_range(130, 1100, 1900);
 };
 
 // output - sends commands to the motors
@@ -314,17 +328,41 @@ float AP_MotorsMulticopter::get_compensation_gain() const
 
 int16_t AP_MotorsMulticopter::calc_thrust_to_pwm(float thrust_in) const
 {
-    return constrain_int16((_throttle_radio_min + _min_throttle + apply_thrust_curve_and_volt_scaling(thrust_in) *
+    return constrain_int16((get_pwm_min() + _min_throttle + apply_thrust_curve_and_volt_scaling(thrust_in) *
-            ( _throttle_radio_max - (_throttle_radio_min + _min_throttle))), _throttle_radio_min + _min_throttle, _throttle_radio_max);
+            ( get_pwm_max() - (get_pwm_min() + _min_throttle))), get_pwm_min() + _min_throttle, get_pwm_max());
+}
+
+// get minimum or maximum pwm value that can be output to motors
+int16_t AP_MotorsMulticopter::get_pwm_min() const
+{
+    // return _pwm_min if both PWM_MIN and PWM_MAX parmeters are defined and valid
+    if ((_pwm_min > 0) && (_pwm_max > 0) && (_pwm_max > _pwm_min)) {
+        return _pwm_min;
+    }
+    return _throttle_radio_min;
+}
+
+// get maximum pwm value that can be output to motors
+int16_t AP_MotorsMulticopter::get_pwm_max() const
+{
+    // return _pwm_max if both PWM_MIN and PWM_MAX parmeters are defined and valid
+    if ((_pwm_min > 0) && (_pwm_max > 0) && (_pwm_max > _pwm_min)) {
+        return _pwm_max;
+    }
+    return _throttle_radio_max;
 }
 
 // set_throttle_range - sets the minimum throttle that will be sent to the engines when they're not off (i.e. to prevents issues with some motors spinning and some not at very low throttle)
 // also sets throttle channel minimum and maximum pwm
 void AP_MotorsMulticopter::set_throttle_range(uint16_t min_throttle, int16_t radio_min, int16_t radio_max)
 {
-    _throttle_radio_min = radio_min;
+    // sanity check
-    _throttle_radio_max = radio_max;
+    if ((radio_max > radio_min) && (min_throttle < (radio_max - radio_min))) {
-    _min_throttle = (float)min_throttle * ((_throttle_radio_max - _throttle_radio_min) / 1000.0f);
+        _throttle_radio_min = radio_min;
+        _throttle_radio_max = radio_max;
+    }
+    // update _min_throttle
+    _min_throttle = (float)min_throttle * ((get_pwm_max() - get_pwm_min()) / 1000.0f);
 }
 
 void AP_MotorsMulticopter::output_logic()
@@ -488,16 +526,17 @@ void AP_MotorsMulticopter::output_logic()
     }
 }
 
-// throttle_pass_through - passes provided pwm directly to all motors - dangerous but used for initialising ESCs
+// passes throttle directly to all motors for ESC calibration.
-//  pwm value is an actual pwm value that will be output, normally in the range of 1000 ~ 2000
+//   throttle_input is in the range of 0 ~ 1 where 0 will send get_pwm_min() and 1 will send get_pwm_max()
-void AP_MotorsMulticopter::throttle_pass_through(int16_t pwm)
+void AP_MotorsMulticopter::set_throttle_passthrough_for_esc_calibration(float throttle_input)
 {
     if (armed()) {
+        uint16_t pwm_out = get_pwm_min() + constrain_float(throttle_input, 0.0f, 1.0f) * (get_pwm_max() - get_pwm_min());
         // send the pilot's input directly to each enabled motor
         hal.rcout->cork();
         for (uint16_t i=0; i < AP_MOTORS_MAX_NUM_MOTORS; i++) {
             if (motor_enabled[i]) {
-                rc_write(i, pwm);
+                rc_write(i, pwm_out);
             }
         }
         hal.rcout->push();
@@ -516,7 +555,7 @@ void AP_MotorsMulticopter::output_motor_mask(float thrust, uint8_t mask)
             if (mask & (1U<<i)) {
                 motor_out = calc_thrust_to_pwm(thrust);
             } else {
-                motor_out = _throttle_radio_min;
+                motor_out = get_pwm_min();
             }
             rc_write(i, motor_out);
         }

libraries/AP_Motors/AP_MotorsMulticopter.h

@@ -10,7 +10,6 @@
 #define AP_MOTORS_DENSITY_COMP 1
 #endif
 
-#define AP_MOTORS_DEFAULT_MIN_THROTTLE  130
 #define AP_MOTORS_DEFAULT_MID_THROTTLE  500
 
 #define AP_MOTORS_SPIN_WHEN_ARMED       70      // spin motors at this PWM value when armed
@@ -78,9 +77,9 @@ public:
 
     void                output_logic();
 
-    // throttle_pass_through - passes provided pwm directly to all motors - dangerous but used for initialising ESCs
+    // passes throttle directly to all motors for ESC calibration.
-    //  pwm value is an actual pwm value that will be output, normally in the range of 1000 ~ 2000
+    //   throttle_input is in the range of 0 ~ 1 where 0 will send get_pwm_min() and 1 will send get_pwm_max()
-    void                throttle_pass_through(int16_t pwm);
+    void                set_throttle_passthrough_for_esc_calibration(float throttle_input);
 
     // get_lift_max - get maximum lift ratio - for logging purposes only
     float               get_lift_max() { return _lift_max; }
@@ -143,6 +142,10 @@ protected:
     // convert thrust (0~1) range back to pwm range
     int16_t             calc_thrust_to_pwm(float thrust_in) const;
 
+    // get minimum or maximum pwm value that can be output to motors
+    int16_t             get_pwm_min() const;
+    int16_t             get_pwm_max() const;
+
     // apply any thrust compensation for the frame
     virtual void        thrust_compensation(void) {}
     
@@ -162,6 +165,8 @@ protected:
     AP_Float            _batt_current_max;      // current over which maximum throttle is limited
     AP_Float            _thr_mix_min;           // throttle vs attitude control prioritisation used when landing (higher values mean we prioritise attitude control over throttle)
     AP_Float            _thr_mix_max;           // throttle vs attitude control prioritisation used during active flight (higher values mean we prioritise attitude control over throttle)
+    AP_Int16            _pwm_min;               // minimum PWM value that will ever be output to the motors (if 0, vehicle's throttle input channel's min pwm used)
+    AP_Int16            _pwm_max;               // maximum PWM value that will ever be output to the motors (if 0, vehicle's throttle input channel's max pwm used)
 
     // internal variables
     bool                motor_enabled[AP_MOTORS_MAX_NUM_MOTORS];    // true if motor is enabled

libraries/AP_Motors/AP_MotorsSingle.cpp

@@ -125,8 +125,8 @@ void AP_MotorsSingle::output_to_motors()
             rc_write(AP_MOTORS_MOT_2, calc_pwm_output_1to1(_pitch_radio_passthrough+_yaw_radio_passthrough, _servo2));
             rc_write(AP_MOTORS_MOT_3, calc_pwm_output_1to1(-_roll_radio_passthrough+_yaw_radio_passthrough, _servo3));
             rc_write(AP_MOTORS_MOT_4, calc_pwm_output_1to1(-_pitch_radio_passthrough+_yaw_radio_passthrough, _servo4));
-            rc_write(AP_MOTORS_MOT_5, _throttle_radio_min);
+            rc_write(AP_MOTORS_MOT_5, get_pwm_min());
-            rc_write(AP_MOTORS_MOT_6, _throttle_radio_min);
+            rc_write(AP_MOTORS_MOT_6, get_pwm_min());
             hal.rcout->push();
             break;
         case SPIN_WHEN_ARMED:
@@ -136,8 +136,8 @@ void AP_MotorsSingle::output_to_motors()
             rc_write(AP_MOTORS_MOT_2, calc_pwm_output_1to1(_throttle_low_end_pct * _actuator_out[1], _servo2));
             rc_write(AP_MOTORS_MOT_3, calc_pwm_output_1to1(_throttle_low_end_pct * _actuator_out[2], _servo3));
             rc_write(AP_MOTORS_MOT_4, calc_pwm_output_1to1(_throttle_low_end_pct * _actuator_out[3], _servo4));
-            rc_write(AP_MOTORS_MOT_5, constrain_int16(_throttle_radio_min + _throttle_low_end_pct * _min_throttle, _throttle_radio_min, _throttle_radio_min + _min_throttle));
+            rc_write(AP_MOTORS_MOT_5, constrain_int16(get_pwm_min() + _throttle_low_end_pct * _min_throttle, get_pwm_min(), get_pwm_min() + _min_throttle));
-            rc_write(AP_MOTORS_MOT_6, constrain_int16(_throttle_radio_min + _throttle_low_end_pct * _min_throttle, _throttle_radio_min, _throttle_radio_min + _min_throttle));
+            rc_write(AP_MOTORS_MOT_6, constrain_int16(get_pwm_min() + _throttle_low_end_pct * _min_throttle, get_pwm_min(), get_pwm_min() + _min_throttle));
             hal.rcout->push();
             break;
         case SPOOL_UP:

libraries/AP_Motors/AP_MotorsTri.cpp

@@ -128,18 +128,18 @@ void AP_MotorsTri::output_to_motors()
         case SHUT_DOWN:
             // sends minimum values out to the motors
             hal.rcout->cork();
-            rc_write(AP_MOTORS_MOT_1, _throttle_radio_min);
+            rc_write(AP_MOTORS_MOT_1, get_pwm_min());
-            rc_write(AP_MOTORS_MOT_2, _throttle_radio_min);
+            rc_write(AP_MOTORS_MOT_2, get_pwm_min());
-            rc_write(AP_MOTORS_MOT_4, _throttle_radio_min);
+            rc_write(AP_MOTORS_MOT_4, get_pwm_min());
             rc_write(AP_MOTORS_CH_TRI_YAW, _yaw_servo_trim);
             hal.rcout->push();
             break;
         case SPIN_WHEN_ARMED:
             // sends output to motors when armed but not flying
             hal.rcout->cork();
-            rc_write(AP_MOTORS_MOT_1, constrain_int16(_throttle_radio_min + _throttle_low_end_pct * _min_throttle, _throttle_radio_min, _throttle_radio_min + _min_throttle));
+            rc_write(AP_MOTORS_MOT_1, constrain_int16(get_pwm_min() + _throttle_low_end_pct * _min_throttle, get_pwm_min(), get_pwm_min() + _min_throttle));
-            rc_write(AP_MOTORS_MOT_2, constrain_int16(_throttle_radio_min + _throttle_low_end_pct * _min_throttle, _throttle_radio_min, _throttle_radio_min + _min_throttle));
+            rc_write(AP_MOTORS_MOT_2, constrain_int16(get_pwm_min() + _throttle_low_end_pct * _min_throttle, get_pwm_min(), get_pwm_min() + _min_throttle));
-            rc_write(AP_MOTORS_MOT_4, constrain_int16(_throttle_radio_min + _throttle_low_end_pct * _min_throttle, _throttle_radio_min, _throttle_radio_min + _min_throttle));
+            rc_write(AP_MOTORS_MOT_4, constrain_int16(get_pwm_min() + _throttle_low_end_pct * _min_throttle, get_pwm_min(), get_pwm_min() + _min_throttle));
             rc_write(AP_MOTORS_CH_TRI_YAW, _yaw_servo_trim);
             hal.rcout->push();
             break;