SRV_Channel: add set_output_norm

libraries/SRV_Channel/SRV_Channel.cpp

@@ -137,6 +137,17 @@ void SRV_Channel::set_output_pwm(uint16_t pwm, bool force)
     }
 }
 
+// set normalised output from -1 to 1, assuming 0 at mid point of servo_min/servo_max
+void SRV_Channel::set_output_norm(float value)
+{
+    // convert normalised value to pwm
+    if (type_angle) {
+        set_output_pwm(pwm_from_angle(value * high_out));
+    } else {
+        set_output_pwm(pwm_from_range(value * high_out));
+    }
+}
+
 // set angular range of scaled output
 void SRV_Channel::set_angle(int16_t angle)
 {

libraries/SRV_Channel/SRV_Channel.h

@@ -174,6 +174,9 @@ public:
     // get the output value as a pwm value
     uint16_t get_output_pwm(void) const { return output_pwm; }
 
+    // set normalised output from -1 to 1, assuming 0 at mid point of servo_min/servo_max
+    void set_output_norm(float value);
+
     // set angular range of scaled output
     void set_angle(int16_t angle);
 
@@ -341,6 +344,9 @@ public:
     // Value is taken from pwm value.  Returns zero on error.
     static float get_output_norm(SRV_Channel::Aux_servo_function_t function);
 
+    // set normalised output (-1 to 1 with 0 at mid point of servo_min/servo_max) for the given function
+    static void set_output_norm(SRV_Channel::Aux_servo_function_t function, float value);
+
     // get output channel mask for a function
     static uint16_t get_output_channel_mask(SRV_Channel::Aux_servo_function_t function);
     

libraries/SRV_Channel/SRV_Channel_aux.cpp

@@ -641,6 +641,20 @@ float SRV_Channels::get_output_norm(SRV_Channel::Aux_servo_function_t function)
     return channels[chan].get_output_norm();
 }
 
+// set normalised output (-1 to 1 with 0 at mid point of servo_min/servo_max) for the given function
+void SRV_Channels::set_output_norm(SRV_Channel::Aux_servo_function_t function, float value)
+{
+    if (!function_assigned(function)) {
+        return;
+    }
+    for (uint8_t i=0; i<NUM_SERVO_CHANNELS; i++) {
+        SRV_Channel &c = channels[i];
+        if (c.function == function) {
+            c.set_output_norm(value);
+        }
+    }
+}
+
 /*
   limit slew rate for an output function to given rate in percent per
   second. This assumes output has not yet done to the hal