RC_Channel: added support for LimitValue settings

this allows you to set a channel failsafe or radio_out to a limit
value

libraries/RC_Channel/RC_Channel.cpp

@@ -127,10 +127,12 @@ RC_Channel::set_reverse(bool reverse)
 }
 
 bool
-RC_Channel::get_reverse(void)
+RC_Channel::get_reverse(void) const
 {
-    if (_reverse==-1) return 1;
-    else return 0;
+    if (_reverse == -1) {
+        return true;
+    }
+    return false;
 }
 
 void
@@ -453,3 +455,18 @@ RC_Channel *RC_Channel::rc_channel(uint8_t i)
     }
     return rc_ch[i];
 }
+
+// return a limit PWM value
+uint16_t RC_Channel::get_limit_pwm(LimitValue limit) const
+{
+    switch (limit) {
+    case RC_CHANNEL_LIMIT_TRIM:
+        return radio_trim;
+    case RC_CHANNEL_LIMIT_MAX:
+        return get_reverse() ? radio_min : radio_max;
+    case RC_CHANNEL_LIMIT_MIN:
+        return get_reverse() ? radio_max : radio_min;
+    }
+    // invalid limit value, return trim
+    return radio_trim;
+}

libraries/RC_Channel/RC_Channel.h

@@ -33,6 +33,13 @@ public:
         }
     }
 
+    // used to get min/max/trim limit value based on _reverse
+    enum LimitValue {
+        RC_CHANNEL_LIMIT_TRIM,
+        RC_CHANNEL_LIMIT_MIN,
+        RC_CHANNEL_LIMIT_MAX
+    };
+
     // setup min and max radio values in CLI
     void        update_min_max();
     void        zero_min_max();
@@ -48,14 +55,20 @@ public:
     void        set_range_out(int16_t low, int16_t high);
     void        set_angle(int16_t angle);
     void        set_reverse(bool reverse);
-    bool        get_reverse(void);
+    bool        get_reverse(void) const;
     void        set_default_dead_zone(int16_t dzone);
+    
+    // get the channel number
+    uint8_t     get_ch_out(void) const { return _ch_out; };
 
     // read input from APM_RC - create a control_in value
     void        set_pwm(int16_t pwm);
     static void set_pwm_all(void);
     void        set_pwm_no_deadzone(int16_t pwm);
 
+    // return a limit PWM value
+    uint16_t    get_limit_pwm(LimitValue limit) const;
+
     // pwm is stored here
     int16_t        radio_in;
 

libraries/RC_Channel/RC_Channel_aux.cpp

@@ -260,6 +260,42 @@ RC_Channel_aux::set_servo_out(RC_Channel_aux::Aux_servo_function_t function, int
     }
 }
 
+/*
+  setup failsafe value for an auxiliary function type to a LimitValue
+ */
+void
+RC_Channel_aux::set_servo_failsafe(RC_Channel_aux::Aux_servo_function_t function, RC_Channel::LimitValue limit)
+{
+    if (!function_assigned(function)) {
+        return;
+    }
+    for (uint8_t i = 0; i < RC_AUX_MAX_CHANNELS; i++) {
+        const RC_Channel_aux *ch = _aux_channels[i];
+        if (ch && ch->function.get() == function) {
+            uint16_t pwm = ch->get_limit_pwm(limit);
+            hal.rcout->set_failsafe_pwm(1U<<ch->get_ch_out(), pwm);
+        }
+    }
+}
+
+/*
+  set radio output value for an auxiliary function type to a LimitValue
+ */
+void
+RC_Channel_aux::set_servo_limit(RC_Channel_aux::Aux_servo_function_t function, RC_Channel::LimitValue limit)
+{
+    if (!function_assigned(function)) {
+        return;
+    }
+    for (uint8_t i = 0; i < RC_AUX_MAX_CHANNELS; i++) {
+        RC_Channel_aux *ch = _aux_channels[i];
+        if (ch && ch->function.get() == function) {
+            uint16_t pwm = ch->get_limit_pwm(limit);
+            ch->radio_out = pwm;
+        }
+    }
+}
+
 /*
   return true if a particular function is assigned to at least one RC channel
  */

libraries/RC_Channel/RC_Channel_aux.h

@@ -99,6 +99,12 @@ public:
 	// set servo_out
 	static void set_servo_out(Aux_servo_function_t function, int16_t value);
 
+	// setup failsafe for an auxillary channel function
+	static void set_servo_failsafe(Aux_servo_function_t function, RC_Channel::LimitValue limit);
+
+	// set servo to a LimitValue
+	static void set_servo_limit(Aux_servo_function_t function, RC_Channel::LimitValue limit);
+
 	// return true if a function is assigned to a channel
 	static bool function_assigned(Aux_servo_function_t function);