oServoSP Object

An oServoSP Object is a Hardware Object that controls the direction and speed of a RC servo-motor that has been modified for continuous rotation.  It is capable of driving the Motor at multiple speeds, in forward or reverse plus free spinning.

The primary function of the oServoSP Object is to allow a stepper motor to be used with the URCP Speed values. 

The oServoSP Object uses a single digital I/O lines to communicate with the RC Servo which handles the voltage and current requirements of the Motor it contains.

How fast the servo motor turns and in which direction it turns is controlled by a single value with a range of  -128 to +127.  When this value is 0, the motor is at free-spinning rest (although turning it will require overcoming the gearing).  When the value is a positive number from 1 to 127, the motor turns forward at the speed indicated by the value.  The higher the value, the faster the motor turns.  When the value is a negative number from -1 to -128, the motor turns backwards at the speed indicated by the value.  The lower the number, the faster the motor turns in reverse.

The physical direction that the motor will turn can be configured to:  forward turns clockwise and reverse turns counter-clockwise  or  forward turns counter-clockwise and reverse turns clockwise.

The oServoSP and oServoSP2 Objects rotate a modified RC servo motor connected to the I/O Line specified by the IOLine property at a speed specified by the Speed and Invert properties.  This object is fairly identical to oServoX with the exception that a Speed of 0 causes the servo to go into a dormant state.  This is useful when using a hobby servo as a drive motor on a robot, there is no "drift" if you don't have the center set perfectly. The oServoSP2 is additionally different in that is uses a radically different control system than the oServoSP does.

The IOLine property specifies which one of the ooPIC's 31 digital I/O Lines is to be used. 
NOTE: The IOLine property MUST be set before the Operate property is set to 1.

When the Speed property is set to 0, the control signals that cause the servo to rotate are suppressed which results in the servo being at rest.  As the Speed property increases, the control signals are adjusted so that the servo will turn forward increasing in speed as the value approaches 127.  And as the Speed property decreases, the control signals are adjusted so that the servo will turn in reverse increasing in speed as the value approaches -128.

When the Operate property is set to 1, the control signals are continuously output to the I/O Line specified by the IOLine  property. This results in the modified RC servo rotating at the specified rate. When the Operate property is cleared to 0, the control signals are suppressed.  This results in the modified RC servo rotating freely.

The Invert property causes the servo to move in the opposite direction.

The oServoSP2 Object uses a different control signal.  Normally the servo control signal is composed of pulses that are sent to the servo at regular intervals and a change in the duration of each pulse controls the servo.  The oServoSP2 differs in that the pulse duration stays the same, but the intervals change to control the servo.  (See the oPWMS Help for more detail on how the control signals for servos work.)

When created, the oServoSP and oServoSP2 Objects also create an instance of the oPWMS object which is used to generate and output the signal that controls the servo.  Modifying any of the properties of the oPWMS instance will affect the oServo Object's operation.  See the oPWMS Help for more detail on how servos are controlled.

The following table lists the properties of the oServoSP Object:

Property	Description
Speed	A value that specifies the speed of the modified servo-motor Object Class:  oPower   Value Range:  -128 to 127 Data Type:  Numeric   Default Value:  0 When operating, a 0 in the Speed property will cause the motor to be at a full stop. When the Speed property is greater than 0, the motor will go forward at a speed specified by the magnitude of the Speed property. The higher the number (up to 127), the faster the motor will turn. If the Speed property is less than 0, then the motor to go backwards at a speed specified by the magnitude of the Speed property. The lower the number (down to negative 128), the faster the motor will turn in reverse. Speed Description -128 Full Reverse -96   -64 Half Reverse -32   0 Stopped 32   64 Half Forward 96   127 Full Forward The Speed property is an oPower object which has properties and methods such as SetFullForward and Stop that can also be used to control the speed of the motor.  Examples:  A.Speed =  64  A.Speed.SetFullForward A.Speed.Stop A.Speed++ A.Speed.Value.Dec
IOLine	A value that specifies which I/O Line is used to control the Servo. Object Class:  oIOLine   Value Range:  0 - 31 Data Type:  Numeric   Default Value:  0 Some I/O Lines have special purposes.  Be sure to see oIOLine help file for details.
Adjust	A value that specifies where the servo's mechanical center is. Object Class:  oAdjust127   Value Range:  0 - 127 Data Type:  Numeric   Default Value:  0
Invert	A value that selects if the physical direction the servo turns is inverted. Object Class:  oSelect0to1L   Value Range:  0 - 1 Data Type:  Numeric   Default Value:  0
Operate	A value that specifies whether or not the modified servo-motor is turning. Object Class:  oOperate   Value Range:  0 - 1 Data Type:  Numeric   Default Value:  0 Operate Constant Description 0 cvOff The servo is off. 1 cvOn The servo is on.
PWM	The I/O function object used to control the servo. Object Class:  oPWMS   Value Range:  0 - 63 Data Type:  Numeric   Default Value:  0
Address	Returns a pointer to the address of the oCounter Object instance. Object Class:  oAddress   Value Range:  0 - 127 Data Type: Pointer (Read Only)   Default Value:  Address of Object

'This program moves a servo. Dim S As New oServoSP Sub Main() S.IOLine = 1 S.Operate =cvTrue Do S = 0: ooPIC.Delay = 150 S = 31: ooPIC.Delay = 150 S = 0: ooPIC.Delay = 150 S = -31: ooPIC.Delay = 150 Loop End Sub

Bugs: Compiler version 5.0.1 did not allow the property Refresh in this object. Fixed in Ver 6.0 by allowing access to the oPWMS object.