TradHeli: add support for drive tail rotors

Repurposed external gyro and made it multi-funcitonal.
required PWM on Ch8 to start the motor in RSC Mode moved up from 100 to 400. This is to facilitate two-stage switching of the motors with PWM>100 starting the tail motor, and PWM>400 starting the main motor.
Additional amendments by Randy

ArduCopter/ArduCopter.pde

@@ -2232,7 +2232,7 @@ static void tuning(){
 
 #if FRAME_CONFIG == HELI_FRAME
     case CH6_HELI_EXTERNAL_GYRO:
-        motors.ext_gyro_gain(tuning_value);
+        motors.ch7_pwm_setpoint(tuning_value);
         break;
 #endif
 

ArduCopter/Attitude.pde

@@ -83,7 +83,7 @@ get_stabilize_yaw(int32_t target_angle)
 
     // do not use rate controllers for helicotpers with external gyros
 #if FRAME_CONFIG == HELI_FRAME
-    if(motors.ext_gyro_enabled()) {
+    if(motors.tail_type() == AP_MOTORS_HELI_TAILTYPE_SERVO_EXTGYRO) {
         g.rc_4.servo_out = constrain_int32(target_rate, -4500, 4500);
     }
 #endif
@@ -446,7 +446,7 @@ run_rate_controllers()
     // convert desired roll and pitch rate to roll and pitch swash angles
     heli_integrated_swash_controller(roll_rate_target_bf, pitch_rate_target_bf);
     // helicopters only use rate controllers for yaw and only when not using an external gyro
-    if(!motors.ext_gyro_enabled()) {
+    if(motors.tail_type() != AP_MOTORS_HELI_TAILTYPE_SERVO_EXTGYRO) {
         g.rc_4.servo_out = get_heli_rate_yaw(yaw_rate_target_bf);
     }else{
         // do not use rate controllers for helicotpers with external gyros

ArduCopter/Log.pde

@@ -239,7 +239,7 @@ struct PACKED log_Motors {
     int16_t motor_out[6];
 #elif FRAME_CONFIG == HELI_FRAME
     int16_t motor_out[4];
-    int16_t ext_gyro_gain;
+    int16_t ch7_pwm_setpoint;
 #else        // quads & TRI_FRAME
     int16_t motor_out[4];
 #endif
@@ -271,7 +271,7 @@ static void Log_Write_Motors()
                          motors.motor_out[AP_MOTORS_MOT_2],
                          motors.motor_out[AP_MOTORS_MOT_3],
                          motors.motor_out[AP_MOTORS_MOT_4]},
-        ext_gyro_gain   : motors.ext_gyro_gain()
+        ch7_pwm_setpoint:motors.ch7_pwm_setpoint()
 #elif FRAME_CONFIG == TRI_FRAME
         motor_out   :   {motors.motor_out[AP_MOTORS_MOT_1],
                          motors.motor_out[AP_MOTORS_MOT_2],

libraries/AP_Motors/AP_MotorsHeli.cpp

@@ -100,12 +100,12 @@ const AP_Param::GroupInfo AP_MotorsHeli::var_info[] PROGMEM = {
     // @User: Standard
     AP_GROUPINFO("COL_MID", 8,      AP_MotorsHeli,  _collective_mid, AP_MOTORS_HELI_COLLECTIVE_MID),
 
-    // @Param: GYR_ENABLE
-    // @DisplayName: External Gyro Enabled
-    // @Description: Enabled/Disable an external rudder gyro connected to channel 7.  With no external gyro a more complex yaw controller is used
-    // @Values: 0:Disabled,1:Enabled
+    // @Param: TAIL_TYPE
+    // @DisplayName: Tail Type
+    // @Description: Tail type selection.  Simpler yaw controller used if external gyro is selected
+    // @Values: 0:Servo only,1:Servo w/ ExtGyro,2:DirectDrive VarPitch,3:DirectDrive FixedPitch
     // @User: Standard
-    AP_GROUPINFO("GYR_ENABLE",9,    AP_MotorsHeli,  _ext_gyro_enabled, 0),
+    AP_GROUPINFO("TAIL_TYPE",9,     AP_MotorsHeli,  _tail_type, AP_MOTORS_HELI_TAILTYPE_SERVO),
 
     // @Param: SWASH_TYPE
     // @DisplayName: Swash Type
@@ -114,14 +114,14 @@ const AP_Param::GroupInfo AP_MotorsHeli::var_info[] PROGMEM = {
     // @User: Standard
     AP_GROUPINFO("SWASH_TYPE",10,   AP_MotorsHeli,  _swash_type, AP_MOTORS_HELI_SWASH_CCPM),
 
-    // @Param: GYR_GAIN
-    // @DisplayName: External Gyro Gain
-    // @Description: PWM sent to the external gyro on Ch7
+    // @Param: CH7_SETPOINT
+    // @DisplayName: Ch7 PWM Setpoint
+    // @Description: PWM output on Ch7 for External Gyro gain or Variable Pitch Direct Drive speed
     // @Range: 1000 2000
     // @Units: PWM
     // @Increment: 10
     // @User: Standard
-    AP_GROUPINFO("GYR_GAIN",11,     AP_MotorsHeli,  _ext_gyro_gain, AP_MOTORS_HELI_EXT_GYRO_GAIN),
+    AP_GROUPINFO("CH7_SETPOINT",    11,     AP_MotorsHeli,  _ch7_pwm_setpoint, 1000),
 
     // @Param: SV_MAN
     // @DisplayName: Manual Servo Mode
@@ -242,12 +242,12 @@ void AP_MotorsHeli::set_update_rate( uint16_t speed_hz )
 void AP_MotorsHeli::enable()
 {
     // enable output channels
-    hal.rcout->enable_ch(_motor_to_channel_map[AP_MOTORS_MOT_1]);            // swash servo 1
-    hal.rcout->enable_ch(_motor_to_channel_map[AP_MOTORS_MOT_2]);            // swash servo 2
-    hal.rcout->enable_ch(_motor_to_channel_map[AP_MOTORS_MOT_3]);            // swash servo 3
-    hal.rcout->enable_ch(_motor_to_channel_map[AP_MOTORS_MOT_4]);            // yaw
-    hal.rcout->enable_ch(AP_MOTORS_HELI_EXT_GYRO);           // for external gyro
-    hal.rcout->enable_ch(AP_MOTORS_HELI_EXT_RSC);            // for external RSC
+    hal.rcout->enable_ch(_motor_to_channel_map[AP_MOTORS_MOT_1]);           // swash servo 1
+    hal.rcout->enable_ch(_motor_to_channel_map[AP_MOTORS_MOT_2]);           // swash servo 2
+    hal.rcout->enable_ch(_motor_to_channel_map[AP_MOTORS_MOT_3]);           // swash servo 3
+    hal.rcout->enable_ch(_motor_to_channel_map[AP_MOTORS_MOT_4]);           // yaw
+    hal.rcout->enable_ch(AP_MOTORS_HELI_AUX);                               // output for gyro gain or direct drive variable pitch tail motor
+    hal.rcout->enable_ch(AP_MOTORS_HELI_RSC);                               // output for main rotor esc
 }
 
 // output_min - sends minimum values out to the motors
@@ -302,8 +302,8 @@ void AP_MotorsHeli::output_test()
     }
 
     // external gyro
-    if (_ext_gyro_enabled) {
-        hal.rcout->write(AP_MOTORS_HELI_EXT_GYRO, _ext_gyro_gain);
+    if (_tail_type == AP_MOTORS_HELI_TAILTYPE_SERVO_EXTGYRO) {
+        hal.rcout->write(AP_MOTORS_HELI_AUX, _ch7_pwm_setpoint);
     }
 
     // servo 4
@@ -578,7 +578,7 @@ void AP_MotorsHeli::move_swash(int16_t roll_out, int16_t pitch_out, int16_t coll
         coll_out_scaled = _collective_out * _collective_scalar + _collective_min - 1000;
 	
         // rudder feed forward based on collective
-        if (!_ext_gyro_enabled) {
+        if (_tail_type != AP_MOTORS_HELI_TAILTYPE_SERVO_EXTGYRO) {
             yaw_offset = _collective_yaw_effect * abs(coll_out_scaled - _collective_mid_pwm);
         }
     }
@@ -621,9 +621,33 @@ void AP_MotorsHeli::move_swash(int16_t roll_out, int16_t pitch_out, int16_t coll
     motor_out[AP_MOTORS_MOT_3] = _servo_3->radio_out;
     motor_out[AP_MOTORS_MOT_4] = _servo_4->radio_out;
 
-    // output gyro value
-    if (_ext_gyro_enabled) {
-        hal.rcout->write(AP_MOTORS_HELI_EXT_GYRO, _ext_gyro_gain);
+    switch (_tail_type) {
+        case AP_MOTORS_HELI_TAILTYPE_SERVO:
+            // do nothing
+            break;
+
+        case AP_MOTORS_HELI_TAILTYPE_SERVO_EXTGYRO:
+            // output gyro value
+            hal.rcout->write(AP_MOTORS_HELI_AUX, _ch7_pwm_setpoint);
+            break;
+
+        case AP_MOTORS_HELI_TAILTYPE_DIRECTDRIVE_VARPITCH:
+            // switch on the motor if Ch8 is not low
+            if (armed() && _rc_8->control_in > 100) {
+                hal.rcout->write(AP_MOTORS_HELI_AUX, _ch7_pwm_setpoint);
+            } else {
+                hal.rcout->write(AP_MOTORS_HELI_AUX, AP_MOTOR_HELI_TAIL_TYPE_DIRECTDRIVE_PWM_MIN);
+            }
+            break;
+
+        case AP_MOTORS_HELI_TAILTYPE_DIRECTDRIVE_FIXEDPITCH:
+            // output fixed-pitch speed control if Ch8 is high
+            if (armed() && _rc_8->control_in > 100) {
+                hal.rcout->write(AP_MOTORS_HELI_AUX, _servo_4->radio_out);
+            } else {
+                hal.rcout->write(AP_MOTORS_HELI_AUX, AP_MOTOR_HELI_TAIL_TYPE_DIRECTDRIVE_PWM_MIN);
+            }
+            break;
     }
 }
 
@@ -668,7 +692,7 @@ void AP_MotorsHeli::rsc_control()
 
     case AP_MOTORS_HELI_RSC_MODE_EXT_GOVERNOR:
 
-        if (armed() && _rc_8->control_in > 100) {
+        if (armed() && _rc_8->control_in > 400) {
             if (_rsc_ramp < _rsc_ramp_up_rate) {
                 _rsc_ramp++;
                 _rsc_output = map(_rsc_ramp, 0, _rsc_ramp_up_rate, 1000, _ext_gov_setpoint);

libraries/AP_Motors/AP_MotorsHeli.h

@@ -24,6 +24,10 @@
 #define AP_MOTORS_HELI_SPEED_DIGITAL_SERVOS     125     // update rate for digital servos
 #define AP_MOTORS_HELI_SPEED_ANALOG_SERVOS      125     // update rate for analog servos
 
+// TradHeli Aux Function Output Channels
+#define AP_MOTORS_HELI_AUX                      CH_7
+#define AP_MOTORS_HELI_RSC                      CH_8
+
 // servo position defaults
 #define AP_MOTORS_HELI_SERVO1_POS               -60
 #define AP_MOTORS_HELI_SERVO2_POS                60
@@ -47,8 +51,18 @@
 // swash min while landed or landing (as a number from 0 ~ 1000
 #define AP_MOTORS_HELI_LAND_COLLECTIVE_MIN      0
 
+// tail types
+#define AP_MOTORS_HELI_TAILTYPE_SERVO                   0
+#define AP_MOTORS_HELI_TAILTYPE_SERVO_EXTGYRO           1
+#define AP_MOTORS_HELI_TAILTYPE_DIRECTDRIVE_VARPITCH    2
+#define AP_MOTORS_HELI_TAILTYPE_DIRECTDRIVE_FIXEDPITCH  3
+
 // default external gyro gain (ch7 out)
-#define AP_MOTORS_HELI_EXT_GYRO_GAIN            1350
+#define AP_MOTORS_HELI_CH7_PWM_SETPOINT                 1350
+
+// minimum outputs for direct drive motors
+#define AP_MOTOR_HELI_TAIL_TYPE_DIRECTDRIVE_PWM_MIN     1000
+
 
 // main rotor speed control types (ch8 out)
 #define AP_MOTORS_HELI_RSC_MODE_NONE            0       // main rotor ESC is directly connected to receiver
@@ -131,12 +145,12 @@ public:
     // allow_arming - returns true if main rotor is spinning and it is ok to arm
     bool allow_arming();
 
-    // ext_gyro_enabled - returns true if we have an external gyro for yaw control
-    bool ext_gyro_enabled() { return _ext_gyro_enabled; }
+    // _tail_type - returns the tail type (servo, servo with ext gyro, direct drive var pitch, direct drive fixed pitch)
+    int16_t tail_type() { return _tail_type; }
 
-    // ext_gyro_gain - gets and sets external gyro gain output on ch7
-    int16_t ext_gyro_gain() { return _ext_gyro_gain; }
-    void ext_gyro_gain(int16_t gain) { _ext_gyro_gain = gain; }
+    // ch7_pwm_setpoint - gets and sets pwm output on ch7 (for gyro gain or direct drive tail motors)
+    int16_t ch7_pwm_setpoint() { return _ch7_pwm_setpoint; }
+    void ch7_pwm_setpoint(int16_t pwm) { _ch7_pwm_setpoint = pwm; }
 
     // has_flybar - returns true if we have a mechical flybar
     bool has_flybar() { return _flybar_mode; }
@@ -209,9 +223,9 @@ private:
     AP_Int16        _collective_min;            // Lowest possible servo position for the swashplate
     AP_Int16        _collective_max;            // Highest possible servo position for the swashplate
     AP_Int16        _collective_mid;            // Swash servo position corresponding to zero collective pitch (or zero lift for Assymetrical blades)
-    AP_Int16        _ext_gyro_enabled;          // Enabled/Disable an external rudder gyro connected to channel 7.  With no external gyro a more complex yaw controller is used
+    AP_Int16        _tail_type;                 // Tail type used: Servo, Servo with external gyro, direct drive variable pitch or direct drive fixed pitch
     AP_Int8         _swash_type;                // Swash Type Setting - either 3-servo CCPM or H1 Mechanical Mixing
-    AP_Int16        _ext_gyro_gain;             // PWM sent to the external gyro on Ch7
+    AP_Int16        _ch7_pwm_setpoint;          // PWM sent to Ch7 for ext gyro gain or direct drive variable pitch motor
     AP_Int8         _servo_manual;              // Pass radio inputs directly to servos during set-up through mission planner
     AP_Int16        _phase_angle;               // Phase angle correction for rotor head.  If pitching the swash forward induces a roll, this can be correct the problem
     AP_Int16        _collective_yaw_effect;     // Feed-forward compensation to automatically add rudder input when collective pitch is increased. Can be positive or negative depending on mechanics.