lejos.nxt.addon.tetrix
Class TetrixServo

java.lang.Object
  lejos.nxt.addon.tetrix.TetrixServo

All Implemented Interfaces:

Servo

public class TetrixServo
extends Object
implements Servo

Basic servo motor abstraction. Servos are driven by a PWM signal from the controller with varying pulse widths controlling the rotational position of the servo actuator shaft.

The HiTechnic Servo Controller allows setting of the PWM output from 0.75 - 2.25ms. Note that some servos may hit their internal mechanical limits at each end of this range causing them to consume excessive current and potentially be damaged.

Author:

Kirk P. Thompson

Method Summary

float	getAngle() Returns the current servo angle as reverse calculated by the last call to setAngle().
int	getpulseWidth() Get the current PWM pulse width for the servo.
void	setAngle(float angle) Sets the angle target of the servo.
void	setpulseWidth(int microSeconds) Set the PWM pulse width for the servo.
void	setRange(int microsecLOW, int microsecHIGH, int travelRange) Set the allowable pulse width operating range of this servo in microseconds and the total travel range.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Detail

setRange

public void setRange(int microsecLOW,
                     int microsecHIGH,
                     int travelRange)
              throws IllegalArgumentException

Set the allowable pulse width operating range of this servo in microseconds and the total travel range. Default for pulse width at instantiation is 750 & 2250 microseconds. Default for travel is 200 degrees.

The midpoint of the pulse width operating range should normally be 1500 microseconds so the range extents should reflect this.

This information must reflect the appropriate specifications and/or empirical characterization data of the specific servo used for the setAngle() method to be able to position the servo accurately.

Specified by:

setRange in interface Servo

Parameters:

microsecLOW - The low end of the servos response/operating range in microseconds

microsecHIGH - The high end of the servos response/operating range in microseconds

travelRange - The total mechanical travel range of the servo in degrees

Throws:

IllegalArgumentException - if the range isn't within 750 and 2250

See Also:

setAngle(float)

setAngle

public void setAngle(float angle)

Sets the angle target of the servo. The positional accuracy of this method requires that setRange() be called with the correct parameters to establish proper ranging conversion to internal controller representation of servo position.

Specified by:

setAngle in interface Servo

Parameters:

angle - Set servo angle in degrees.

See Also:

setRange(int, int, int), getAngle()

getAngle

public float getAngle()

Returns the current servo angle as reverse calculated by the last call to setAngle(). This is calculated from the internal byte representation used (calculated by setAngle()) to control the servo so the resolution will be affected by ranging factors set with setRange()

The actual physical servo position may or may not be at the reported angle if mechanical limits have been reached.

Specified by:

getAngle in interface Servo

Returns:

Current servo angle

See Also:

setRange(int, int, int), setAngle(float)

setpulseWidth

public void setpulseWidth(int microSeconds)
                   throws IllegalArgumentException

Set the PWM pulse width for the servo. This must be in the range defined for the servo. This method allows manipulation of the servo position based on absolute pulse widths in microseconds.

A servo pulse of 1500 microseconds (1.5 ms) width will typically set the servo to its "neutral" position. This is the "standard pulse servo mode" used by all hobby analog servos.

The HiTechic Servo Controller allows setting of the PWM output from 750 to 2250 microseconds with a step resolution of 5.88 microseconds (1 byte is used to control the pulse width output) and this method will calculate and use the stepped value closest to value passed in microSeconds.

Note that some servos may hit their internal mechanical limits at each end of this range causing them to consume excessive current and potentially be damaged.

Specified by:

setpulseWidth in interface Servo

Parameters:

microSeconds - The pulse width time in microseconds

Throws:

IllegalArgumentException - if the range isn't within 750 and 2250

See Also:

setRange(int, int, int)

getpulseWidth

public int getpulseWidth()

Description copied from interface: Servo

Get the current PWM pulse width for the servo.

Specified by:

getpulseWidth in interface Servo

Returns:

The pulse width time in microseconds