ISRStepper

Interrupt driven stepper motor module. Uses Timer1 to generate interrupt at correct interval for motor speed. Each interrupt advances motor to next step.
Public flag "MovementComplete" indicates when commanded position or number of steps have been reached.

ISRStepper Motor Module

Motor may be connected to any four pins on one port.

Subs and Functions

(see code for parameters and other information)

Note: All angles are * 100 (i.e. 90 degrees in reality = 9000 in module)

Move - moves motor specified number of steps with given direction and speed.
MovementComplete = True when finished

MoveToPosition - moves motor as close as possible to specified degree position (0 - 359.99) with given direction and speed.
MovementComplete = True when finished

ShortestMoveToPosition - moves motor in the shortest direction as close as possible to specified degree position (0 - 359.99) with given speed.
MovementComplete = True when finished

MoveToLimit - moves motor in specified direction until a given PIC pin goes high. Can be used with a limit switch for calibrating the system to a known position. Optional StepTimeout sets number of steps after which movement stops regardless of limit switch state.
MovementComplete = True when finished. LimitSwitchReached = True if movement stopped because limit switch was triggered, False if StepTimeout reached.

ResetPosition - sets module's Position variable to specified value. Useful for setting zero point after MoveToLimit or other calibration.

Rotate - turns motor through a given number of complete revolutions plus a number of degrees (0 - 359.99).
MovementComplete = True when finished

PowerOff / PowerOn - stops / resumes output on stepper motor pins. PowerOff cancels any movement in progress.

Pause / Resume - Pauses / resumes current movement.

GetPosition - returns current degree position of motor (0 - 359.99)

GetStep - returns current step number (1 - 8)

Options

#option ISRStepper_Port = PORTB            'Which PORT stepper is connected to

#option ISRStepper_Pin1 = %00000001        '}
#option ISRStepper_Pin2 = %00000010        '}Which 4 pins the stepper motor is
#option ISRStepper_Pin3 = %00000100        '}connected to. (Pins 0-3 shown here)
#option ISRStepper_Pin4 = %00001000        '}

#option ISRStepper_FullStepSize = 750      'Degrees motor moves in one full step
#option ISRStepper_HalfStepMode = True     'Drive motor in half step mode?
#option ISRStepper_DefaultSpeed = 4        'Default delay in mS between steps

#option ISRStepper_Priority = ipHigh       'Stepper interrupt priority

#option ISRStepper_LimitSwitch = PORTB.4   'Pin which limit switch is connected
                                           'to.  Note: Active HIGH

Usage Example

#option ISRStepper_Port = PORTB            '}
#option ISRStepper_Pin1 = %00000001        '}Stepper connected to pins 0,2,3 & 5
#option ISRStepper_Pin2 = %00000100        '}of PORTB
#option ISRStepper_Pin3 = %00001000        '}
#option ISRStepper_Pin4 = %00100000        '}

#option ISRStepper_FullStepSize = 500      'Full step is 5 degrees
#option ISRStepper_HalfStepMode = True     'Drive stepper in half-step mode
#option ISRStepper_DefaultSpeed = 4        'Default 4mS between steps

#option ISRStepper_Priority = ipHigh       'Stepper interrupt has high priority

#option ISRStepper_LimitSwitch = PORTA.0   'Pin for limit switch


Include "ISRStepper.bas"

Const Clockwise = True
Const AntiClockwise = False

'Set PortA.0 to input (limit switch)
TRISA = %00000001


'Move motor 10 steps clockwise at default speed
ISRStepper.Move(Clockwise, 10)
Repeat

    'do useful things...

Until ISRStepper.MovementComplete = True


'Move motor to 120 degrees in shortest direction
ISRStepper.ShortestMoveToPosition(12000)
Repeat

    'do useful things...

Until ISRStepper.MovementComplete = True


'Move motor anti-clockwise at 8mS between steps until it reaches limit switch.
'If limit switch not reached after 100 steps then stop driving motor:
ISRStepper.MoveToLimit(AntiClockwise, 8, 100)

Repeat
Until ISRStepper.MovementComplete = True

If ISRStepper.LimitSwitchReached = True Then

    'Limit switch reached succesfully, set zero point     
    ISRStepper.ResetPosition(0)

Else

    'Limit switch not reached, must be a mechanical problem, turn off motor
    ISRStepper.PowerOff()

EndIf


'Rotate 3 1/4 times clockwise.  If PORTB.6 goes High then pause movement, resume
'movement when PORTB.6 goes low again:
ISRStepper.Rotate(3, 9000, Clockwise)

Repeat

    If PORTB.6 = 1 Then

        ISRStepper.Pause()

        Repeat
        Until PORTB.6 = 0

        ISRStepper.Resume()

    EndIf

Until ISRStepper.MovementComplete = True

Module Code

{
********************************************************************************
*  Name    : Interrupt Driven Stepper Motor Module                             *
*  Author  : AndyO                                                             *
*  Notice  : Copyright (c) 2008 AndyO                                          *
*          : All Rights Reserved                                               *
*  Date    : 20/03/2008                                                        *
*  Version : 1.0                                                               *
*  Notes   : Uses Timer1 and Compare module to trigger interrupt at correct    *
*          : interval for motor move speed                                     *
*          :                                                                   *
*          : For use with 4 phase unipolar stepper motor                       *
*          :                                                                   *
*          : All angles * 100 (i.e. 7.5deg in reality = 750 in module)         *
********************************************************************************
}

Module ISRStepper 


'===============================================================================
'User definable options
'-------------------------------------------------------------------------------

#option ISRStepper_Port = PORTB            'Which PORT stepper is connected to

#option ISRStepper_Pin1 = %00000001        '}
#option ISRStepper_Pin2 = %00000010        '}Which 4 pins the stepper motor is
#option ISRStepper_Pin3 = %00000100        '}connected to. (Pins 0-3 shown here)
#option ISRStepper_Pin4 = %00001000        '}

#option ISRStepper_FullStepSize = 750      'Degrees motor moves in one full step
#option ISRStepper_HalfStepMode = True     'Drive motor in half step mode?
#option ISRStepper_DefaultSpeed = 4        'Default delay in mS between steps

#option ISRStepper_Priority = ipHigh       'Stepper interrupt priority

#option ISRStepper_LimitSwitch = PORTB.4   'Pin which limit switch is connected
                                           'to.  Note: Active HIGH


#option ISRStepper_TRIS = getTRIS(ISRStepper_Port)


'===============================================================================
'Variable and Const Declarations
'-------------------------------------------------------------------------------

'---Bring options into module

Private Const
    #if ISRStepper_HalfStepMode Then

        StepJump = 1,
        StepSize = ISRStepper_FullStepSize / 2,

    #else

        StepJump = 2,
        StepSize = ISRStepper_FullStepSize,

    #endif

    Pin1 As Byte = ISRStepper_Pin1,
    Pin2 As Byte = ISRStepper_Pin2,
    Pin3 As Byte = ISRStepper_Pin3,
    Pin4 As Byte = ISRStepper_Pin4,

    'PortMask used to turn on/off only the pins the stepper is connnected to

    PortMask As Byte = Not(Pin1 Or Pin2 Or Pin3 Or Pin4),


    'Step masks used to turn on the correct pins for the current step.
    'Constant array loaded with half-step sequence    

    StepMask(8) As Byte = (Pin1,                                   'Step 1: 0001
                           Pin1 Or Pin2,                           'Step 2: 0011
                           Pin2,                                   'Step 3: 0010
                           Pin2 Or Pin3,                           'Step 4: 0110
                           Pin3,                                   'Step 5: 0100
                           Pin3 Or Pin4,                           'Step 6: 1100
                           Pin4,                                   'Step 7: 1000
                           Pin4 Or Pin1),                          'Step 8: 1001


    DefaultSpeed = ISRStepper_DefaultSpeed,
    StepperPriority = ISRStepper_Priority,
    Timer1mSCount = _clock * 250               'No. of ticks Timer1 makes in 1mS


Private Dim
    StepperPort As ISRStepper_Port,
    LimitSwitch As [email protected],
    StepperTRIS As ISRStepper_TRIS


'---Timer1 & CCP Module Registers

Private Dim
    Timer1Value As TMR1L.AsWord,
    Timer1On As T1CON.Booleans(0),

    CompareValue As CCPR1L.AsWord,
    CompareInterruptFlag As PIR1.Booleans(2),
    CompareInterruptEnable As PIE1.Booleans(2),
    CompareInterruptHighPriority As IPR1.Booleans(2),
    CompareUsingTimer3 As T3CON.Booleans(3)


'---Private Variables

Private Dim CurrentStep As Byte
Private Dim Position As Word
Private Dim RotateClockwise As Boolean

Private Dim StepCount As Word
Private Dim MoveToLimitMode As Boolean
Private Dim UseLimitTimeout As Boolean

Private Dim Distance As Word
Private Dim DistanceAntiClockwise As Word


'---Public Variables

Public Dim MovementComplete As Boolean
Public Dim LimitSwitchReached As Boolean


'===============================================================================
'Helper Subs and Functions (Private - can't be called from main program)
'-------------------------------------------------------------------------------

'~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
'Name:      SingleStep (Inline)
'Purpose:   Updates StepCount and Position Variables, set relevant pins high for
'           current step.  
'           
'Note:      Inline sub - doesn't save codespace but used to improve readability
'           of interrupt routine.
'~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Private Inline Sub SingleStep()

    'Adjust CurrentStep according to direction and update Position variable
    If RotateClockwise Then                            
        CurrentStep = CurrentStep + StepJump

        Position = Position + StepSize

        If Position > 35999 Then
            Position = Position - 36000

        EndIf

    Else                                                    
        CurrentStep = CurrentStep - StepJump

        'Going anti-clockwise so need to check for zero-cross
        If Position >= StepSize Then
            Position = Position - StepSize

        Else
            Position = (36000 + Position) - StepSize

        EndIf

    EndIf                                                   


    Select CurrentStep                                      

        Case >8                                              
            CurrentStep = StepJump                                 

        Case 0                                              
            CurrentStep = 8                                 

    EndSelect                                               


    'AND'ing Port with PortMask sets only stepper pins to '0' ignores others
    'OR'ing Port with StepMask for current step sets the relevant pins high
    StepperPort = (StepperPort And PortMask) Or StepMask(CurrentStep - 1)

End Sub



'~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
'Name:      BeginMove
'Purpose:   Enables interrupt, allowing motor movement to begin.
'           
'           Loads necessary values into Compare register and Timer1, starts 
'           Timer1 and enables interrupt
'~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Private Sub BeginMove(pSpeed As Byte)

    'Load compare module with appropriate value depending on speed
    CompareValue = pSpeed * Timer1mSCount - 1

    'Set Timer1 to just before compare value and turn it on
    Timer1Value = CompareValue - 1
    Timer1On = True

    'Turn on interrupt - interrupt triggered when Timer1 = compare value
    CompareInterruptEnable = True    

End Sub



'===============================================================================
'Interrupts
'-------------------------------------------------------------------------------

'~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
'Name:      OnTimer
'Purpose:   Interrupt triggered when Timer1 reaches CCPR1 register value
'           (CompareValue).
'
'           Occurs every x mS where x is the speed setting for the movement.
'
'           Movement finishes when number of steps have been taken or limit
'           switch reached (depending on what mode we're in).  Once movement is
'           complete, interrupt is un-enabled and MovementComplete flag = True.
'~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Interrupt OnTimer(StepperPriority)

    'Context save
    Save(0)

    If MoveToLimitMode = True Then

        If UseLimitTimeout = True Then
        'Timeout specified (StepCount holds StepTimeout)

            If LimitSwitch = 0 And StepCount > 0 Then

                SingleStep()
                Dec(StepCount)

            ElseIf LimitSwitch = 1 And StepCount > 0 Then
            'Limit switch was reached in time

                MovementComplete = True
                LimitSwitchReached = True
                Timer1On = False
                CompareInterruptEnable = False

            Else
            'Ran out of steps before the limit switch was reached

                MovementComplete = True
                LimitSwitchReached = False
                Timer1On = False
                CompareInterruptEnable = False

            EndIf


        Else
        'No timeout specified - just keep moving until the limit switch triggers

            If LimitSwitch = 0 Then

                SingleStep()

            Else
            'Limit switch reached

                MovementComplete = True
                LimitSwitchReached = True
                Timer1On = False
                CompareInterruptEnable = False

            EndIf


        EndIf

    Else
    'Not moving to the limit switch - instead move until StepCount = 0

        If StepCount > 0 Then

            SingleStep()
            Dec(StepCount)

        Else

            MovementComplete = True
            Timer1On = False
            CompareInterruptEnable = False

        EndIf 

    EndIf   

    'Context restore
    Restore

    CompareInterruptFlag = False

End Interrupt



'===============================================================================
'Public Subs and Functions
'-------------------------------------------------------------------------------

'~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
'Name:      Move
'Purpose:   Moves stepper with specified direction, number of steps and speed.
'
'           MovementComplete flag = True when move is finished.
'~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Public Sub Move(pRotateClockwise As Boolean = True, pNumberOfSteps As Word = 1, pSpeed As Byte = DefaultSpeed)

    MovementComplete = False

    MoveToLimitMode = False

    RotateClockwise = pRotateClockwise
    StepCount = pNumberOfSteps

    BeginMove(pSpeed)

End Sub



'~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
'Name:      MoveToLimit
'Purpose:   Moves stepper with specified direction and speed until limit switch
'           is triggered.  Optional pStepTimeout sets number of steps after 
'           which movement stops regardless of limit switch state.
'
'           Once movement complete (indicated by MovementComplete flag = True),
'           LimitSwitchReached flag = True if movement stopped because the limit
'           switch was triggered; flag = False if movement stopped because
'           StepTimeout was reached.
'~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Public Sub MoveToLimit(pRotateClockwise As Boolean = True, pSpeed As Byte = DefaultSpeed, pStepTimeout As Word = 0)

    MovementComplete = False
    LimitSwitchReached = False

    MoveToLimitMode = True


    If pStepTimeout > 0 Then
    'Timeout has been specified

        UseLimitTimeout = True
        StepCount = pStepTimeout                     

    Else
    'No timeout specified

        UseLimitTimeout = False

    EndIf

    RotateClockwise = pRotateClockwise

    BeginMove(pSpeed)

End Sub



'~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
'Name:      ResetPosition
'Purpose:   Sets Position variable to specified value.  Useful for setting zero
'           point after move to limit switch or other calibration.
'~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Public Sub ResetPosition(pPosition As Word = 0)

    Position = pPosition

End Sub    



'~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
'Name:      MoveToPosition
'Purpose:   Moves stepper as close as possible to desired position with
'           specified direction and speed.
'
'           MovementComplete flag = True when move is finished.
'
'Note:      All positions * 100 i.e. 90 deg = 9000
'
'           Final position of stepper may vary from desired position due to
'           resolution of step size.
'~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Public Sub MoveToPosition(pDesiredPosition As Word, pRotateClockwise As Boolean = True, pSpeed As Byte = DefaultSpeed)

    MovementComplete = False

    MoveToLimitMode = False

    RotateClockwise = pRotateClockwise

    'If desired position is 360deg or over then bring it into 0 - 35999 range
    If pDesiredPosition > 35999 Then

        pDesiredPosition = pDesiredPosition - 36000

    EndIf

    'Calculate distance (in degrees) motor needs to travel
    If pDesiredPosition > Position Then

        If pRotateClockwise Then
            Distance = pDesiredPosition - Position

        Else
            Distance = (36000 - pDesiredPosition) + Position

        EndIf

    Else

        If pRotateClockwise Then
            Distance = (36000 - Position) + pDesiredPosition

        Else
            Distance = Position - pDesiredPosition

        EndIf

    EndIf


    If Distance > StepSize / 2 And Distance < 36000 - (StepSize / 2) Then
    'Only move if desired position is more than 1/2 a step from current position

        'Convert degree distance to number of steps
        StepCount = Distance / StepSize

        'If motor will stop more than 1/2 a step before desired position then
        'better to overshoot by a step
        If Distance Mod StepSize > StepSize / 2 Then

            StepCount = StepCount + 1

        EndIf

        BeginMove(pSpeed)

    Else

        MovementComplete = true

    EndIf        

End Sub



'~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
'Name:      ShortestMoveToPosition
'Purpose:   Moves stepper as close as possible to desired position with
'           specified speed in the shortest direction.
'
'           MovementComplete flag = True when move is finished.
'
'Note:      All positions * 100 i.e. 90 deg = 9000
'
'           Final position of stepper may vary from desired position due to
'           resolution of step size.
'~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Public Sub ShortestMoveToPosition(pDesiredPosition As Word, pSpeed As Byte = DefaultSpeed)

    MovementComplete = False

    MoveToLimitMode = False

    'If desired position is 360deg or over then bring it into 0 - 35999 range
    If pDesiredPosition > 35999 Then

        pDesiredPosition = pDesiredPosition - 36000

    EndIf


    'Calculate distance between desired and actual position in each direction
    If pDesiredPosition > Position Then

        Distance = pDesiredPosition - Position
        DistanceAntiClockwise = (36000 - pDesiredPosition) + Position

    Else

        Distance = (36000 - Position) + pDesiredPosition
        DistanceAntiClockwise = Position - pDesiredPosition

    EndIf


    'Choose the shortest distance
    If Distance > DistanceAntiClockwise Then

        Distance = DistanceAntiClockwise
        RotateClockwise = False

    Else

        RotateClockwise = True

    EndIf


    'Convert degree distance to number of steps
    StepCount = Distance / StepSize

    'If motor will stop more than 1/2 a step before desired position then better
    'to overshoot by a step
    If Distance Mod StepSize > StepSize / 2 Then

        StepCount = StepCount + 1

    EndIf

    BeginMove(pSpeed)

End Sub



'~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
'Name:      Rotate
'Purpose:   Rotates stepper the specified number of complete revolutions plus
'           0-35999 additional degrees with specified direction and speed.
'
'           MovementComplete flag = True when move is finished.
'~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Public Sub Rotate(pNumberOfRotations As Byte = 1, pAdditionalDegrees As Word = 0, pRotateClockwise As Boolean = True, pSpeed As Byte = DefaultSpeed)

    MovementComplete = False

    MoveToLimitMode = False

    RotateClockwise = pRotateClockwise

    'If additional degrees is 360deg or over then bring it into 0 - 35999 range
    If pAdditionalDegrees > 35999 Then

        pAdditionalDegrees = pAdditionalDegrees - 36000

    EndIf 

    'Convert additional degree distance to number of steps
    StepCount = pAdditionalDegrees / StepSize

    'If motor will stop more than 1/2 a step before desired position then better
    'to overshoot by a step
    If pAdditionalDegrees Mod StepSize > StepSize / 2 Then

        StepCount = StepCount + 1

    EndIf    

    'Add correct number of steps for complete rotations
    StepCount = StepCount + (pNumberOfRotations * (36000 / StepSize))

    BeginMove(pSpeed)

End Sub



'~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
'Name:      PowerOff
'Purpose:   Stops output on stepper pins and cancels any movement in progress
'
'Note:      Stepper won't hold position
'~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Public Sub PowerOff()

    StepCount = 0
    StepperPort = StepperPort And PortMask

End Sub



'~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
'Name:      PowerOn
'Purpose:   Resumes output on stepper pins
'~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Public Sub PowerOn()

    StepperPort = (StepperPort And PortMask) Or StepMask(CurrentStep - 1)

End Sub



'~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
'Name:      Pause
'Purpose:   Pauses any motor movement in progress
'
'Note:      Continues to output current step on output pins
'~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Public Sub Pause()

    Timer1On = False

End Sub



'~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
'Name:      Resume
'Purpose:   Resumes movment after pause
'~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Public Sub Resume()

    Timer1On = True

End Sub



'~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
'Name:      GetStep  
'Returns:   Number of current step (1 - 8)
'~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Public Function GetStep() As Byte

    result = CurrentStep

End Function



'~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
'Name:      GetPosition
'Returns:   Current stepper position (0 - 35,999)
'
'Note:      All positions * 100 i.e. 90 deg = 9000
'~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Public Function GetPosition() As Word

    result = Position

End Function



'===============================================================================
'Module Initialisation
'-------------------------------------------------------------------------------

'Initialise vars
CurrentStep = StepJump
Position = 0
StepCount = 0
MovementComplete = True
MoveToLimitMode = False
LimitSwitchReached = False

'Set TRIS without changing non-stepper pins
StepperTRIS = StepperTRIS And PortMask


'Initialise CCP and Timer1 modules:
CompareUsingTimer3 = False                      'Compare module use timer1

#if ISRStepper_Priority = ipHigh Then           '}
    CompareInterruptHighPriority = True         '}
#else                                           '}Set interrupt priority
    CompareInterruptHighPriority = False        '}
#endif                                          '}

T1CON = %00000000                               'No pre-scaler, timer 1 off

CCP1CON = %00001011                             'Set special event trigger
                                                '(Resets Timer1 and triggers
                                                'interrupt when Timer1 value
                                                'reaches CCPR1 register value)

Enable(OnTimer)