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 ISRStepper_LimitSwitch.ISRStepper_LimitSwitch@, 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)