Netduino - Class Servo - 4.3.1

Question

I'm using the new version of the class of Chris:

/*
 * Servo NETMF Driver
 *      Coded by Chris Seto August 2010
 *      <chris@chrisseto.com> 
 *      
 * Use this code for whatveer you want. Modify it, redistribute it, I don't care.
 * I do ask that you please keep this header intact, however.
 * If you modfy the driver, please include your contribution below:
 * 
 * Chris Seto: Inital release (1.0)
 * Chris Seto: Netduino port (1.0 -> Netduino branch)
 * Chris Seto: bool pin state fix (1.1 -> Netduino branch)
 * 
 * 
 * */
using System;
using Microsoft.SPOT;
using Microsoft.SPOT.Hardware;
using SecretLabs.NETMF.Hardware;
using SecretLabs.NETMF.Hardware.Netduino;

namespace Servo_API
{
    public class Servo : IDisposable
    {
        /// <summary>
        /// PWM handle
        /// </summary>
        private PWM servo;

        /// <summary>
        /// Timings range
        /// </summary>
        private int[] range = new int[2];

        /// <summary>
        /// Set servo inversion
        /// </summary>
        public bool inverted = false;

        /// <summary>
        /// Create the PWM Channel, set it low and configure timings
        /// </summary>
        /// <param name="pin"></param>
        public Servo(Cpu.PWMChannel channelPin)
        {
            // Init the PWM pin
            servo = new PWM((Cpu.PWMChannel)channelPin, 20000, 1500, PWM.ScaleFactor.Microseconds, false);

            servo.DutyCycle = 0;
            // Typical settings
            range[0] = 1000;
            range[1] = 2000;
        }

        public void Dispose()
        {
            disengage();
            servo.Dispose();
        }

        /// <summary>
        /// Allow the user to set cutom timings
        /// </summary>
        /// <param name="fullLeft"></param>
        /// <param name="fullRight"></param>
        public void setRange(int fullLeft, int fullRight)
        {
            range[1] = fullLeft;
            range[0] = fullRight;
        }

        /// <summary>
        /// Disengage the servo. 
        /// The servo motor will stop trying to maintain an angle
        /// </summary>
        public void disengage()
        {
            // See what the Netduino team say about this... 
            servo.DutyCycle = 0; //SetDutyCycle(0);
        }

        /// <summary>
        /// Set the servo degree
        /// </summary>
        public double Degree
        {
            set
            {
                /// Range checks
                if (value > 180)
                    value = 180;

                if (value < 0)
                    value = 0;

                // Are we inverted?
                if (inverted)
                    value = 180 - value;

                // Set the pulse
                //servo.SetPulse(20000, (uint)map((long)value, 0, 180, range[0], range[1]));
                servo.Duration = (uint)map((long)value, 0, 180, range[0], range[1]);
            }
        }

        /// <summary>
        /// Used internally to map a value of one scale to another
        /// </summary>
        /// <param name="x"></param>
        /// <param name="in_min"></param>
        /// <param name="in_max"></param>
        /// <param name="out_min"></param>
        /// <param name="out_max"></param>
        /// <returns></returns>
        private long map(long x, long in_min, long in_max, long out_min, long out_max)
        {
            return (x - in_min) * (out_max - out_min) / (in_max - in_min) + out_min;
        }
    }
}

---

Servo servo = new Servo(PWMChannels.PWM_PIN_D5);
servo.Degree = 30; // Change 'While' to 'For' to limit how many time it repeats
         for (int j = 0; j < 3; j++)
         {
             for (int i = 0; i <= 180; i++)
             {
                 servo.Degree = i;
                 Thread.Sleep(10);
             }


             for (int i = 180; i >= 0; i--)
             {
                 servo.Degree = i;
                 Thread.Sleep(10);
             }
         }

I connecting servo in 3.3v gnd port 5 digital in Netduino

my servo is: http://www.hobbyking.com/hobbyking/store/_14458_hobbyking_939mg_metal_gear_servo_2_5kg_12_5g_0_14sec.html

not working! why? someone has already done something that works?

Answer 1

Missed .start()

My Class, working 100% Netduino - servo class, .NET 4.3.1

using System;
using Microsoft.SPOT;
using Microsoft.SPOT.Hardware;
using SecretLabs.NETMF.Hardware;
using SecretLabs.NETMF.Hardware.Netduino;

namespace Servo_API
{
    public class Servo : IDisposable
    {
        /// <summary>
        /// PWM handle
        /// </summary>
        private PWM servo;

        /// <summary>
        /// Timings range
        /// </summary>
        private int[] range = new int[2];

        /// <summary>
        /// Set servo inversion
        /// </summary>
        public bool inverted = false;

        /// <summary>
        /// Create the PWM Channel, set it low and configure timings
        /// </summary>
        /// <param name="pin"></param>
        public Servo(Cpu.PWMChannel channelPin)
        {
            // Init the PWM pin
           // servo = new PWM((Cpu.PWMChannel)channelPin, 20000, 1500, PWM.ScaleFactor.Microseconds, false);
            servo = new PWM(PWMChannels.PWM_PIN_D5, 20000, 1500, Microsoft.SPOT.Hardware.PWM.ScaleFactor.Microseconds, false);
            servo.Period = 20000;

            // Typical settings
            range[0] = 1000;
            range[1] = 2000;
        }

        public void Dispose()
        {
            disengage();
            servo.Dispose();
        }

        /// <summary>
        /// Allow the user to set cutom timings
        /// </summary>
        /// <param name="fullLeft"></param>
        /// <param name="fullRight"></param>
        public void setRange(int fullLeft, int fullRight)
        {
            range[1] = fullLeft;
            range[0] = fullRight;
        }

        /// <summary>
        /// Disengage the servo. 
        /// The servo motor will stop trying to maintain an angle
        /// </summary>
        public void disengage()
        {
            // See what the Netduino team say about this... 
            servo.DutyCycle = 0; //SetDutyCycle(0);
        }

        /// <summary>
        /// Set the servo degree
        /// </summary>
        public double Degree
        {
            set
            {
                /// Range checks
                if (value > 180)
                    value = 180;

                if (value < 0)
                    value = 0;

                // Are we inverted?
                if (inverted)
                    value = 180 - value;

                // Set the pulse
                //servo.SetPulse(20000, (uint)map((long)value, 0, 180, range[0], range[1]));
                servo.Duration = (uint)map((long)value, 0, 180, range[0], range[1]);
                servo.Start();
            }
        }


        private long map(long x, long in_min, long in_max, long out_min, long out_max)
        {
            return (x - in_min) * (out_max - out_min) / (in_max - in_min) + out_min;
        }
    }
}

and I call this:

   Servo tt = new Servo(Cpu.PWMChannel.PWM_5);
            tt.Degree = 30;
            tt.setRange(1000, 2000);
            tt.Dispose();
        }

Answer 2

I haven't used that lib but the servo should not be powered by 3.3v, you should connect it separately to the 5v pin.

Another thing you can try is to create a new PWM:

PWM servo = new PWM(Pins.GPIO_PIN_D9);

Also, so we can help, you should describe its behavior... if it twitches, moves slowly, something... plus the way you've connected it (diagram, photo).