2 Modules for controlling unipolar stepper motors. The first - listed below - is simple but occupies the PIC 100% whilst the motor is moving. The 2nd - listed here - is interrupt driven so the main program can get on with other things whilst the motor is moving to its new position.
Motor may be connected to any four pins on one port.
(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.
MoveToPosition - moves motor as close as possible to specified degree position (0 - 359.99) with given direction and speed.
ShortestMoveToPosition - moves motor in the shortest direction as close as possible to specified degree position (0 - 359.99) with given speed.
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.
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.
PowerOff / PowerOn - stops / resumes output on stepper motor pins.
GetPosition - returns current degree position of motor (0 - 359.99)
GetStep - returns current step number (1 - 8)
#option Stepper_Port = PORTB 'Which PORT stepper is connected to #option Stepper_Pin1 = %00000001 '} #option Stepper_Pin2 = %00000010 '}Which 4 pins the stepper motor is #option Stepper_Pin3 = %00000100 '}connected to. (Pins 0-3 shown here) #option Stepper_Pin4 = %00001000 '} #option Stepper_FullStepSize = 750 'Degrees motor moves in one full step #option Stepper_HalfStepMode = True 'Drive motor in half step mode? #option Stepper_DefaultSpeed = 4 'Default delay in mS between steps #option Stepper_LimitSwitch = PORTB.4 'Pin which limit switch is connected to. 'Note: Active HIGH
#option Stepper_Port = PORTB '} #option Stepper_Pin1 = %00000001 '}Stepper connected to pins 0,2,3 & 5 #option Stepper_Pin2 = %00000100 '}of PORTB #option Stepper_Pin3 = %00001000 '} #option Stepper_Pin4 = %00100000 '} #option Stepper_FullStepSize = 500 'Full step is 5 degrees #option Stepper_HalfStepMode = True 'Drive stepper in half-step mode #option Stepper_DefaultSpeed = 4 'Default 4mS between steps #option Stepper_LimitSwitch = PORTA.0 'Pin for limit switch Include "Stepper.bas" Dim MotorPosition As Word Const Clockwise = True Const AntiClockwise = False 'Set PortA.0 to input (limit switch) TRISA = %00000001 'Move motor 10 steps clockwise at default speed Stepper.Move(Clockwise, 10) '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. If Stepper.MoveToLimit(AntiClockwise, 8, 100) Then 'Limit switch reached succesfully, set zero point Stepper.ResetPosition(0) Else 'Limit switch not reached, must be a mechanical problem, turn off motor Stepper.PowerOff() EndIf 'Move motor to 120 degrees in shortest direction, store new position in variable MotorPosition = Stepper.ShortestMoveToPosition(12000) 'Rotate 3 1/2 times clockwise: 'First do three complete revolutions Stepper.Rotate(3, Clockwise) 'Then move to a position 180 degrees from the current position Stepper.MoveToPosition(Stepper.GetPosition() + 18000, Clockwise)
{ ******************************************************************************** * Name : Stepper Motor Module * * Author : AndyO * * Notice : Copyright (c) 2008 AndyO * * : All Rights Reserved * * Date : 01/03/2008 * * Version : 1.0 * * Notes : For use with 4 phase unipolar stepper motor * * : * * : All angles * 100 (i.e. 7.5deg in reality = 750 in module) * ******************************************************************************** } Module Stepper Include "Math.bas" '=============================================================================== 'User definable options '------------------------------------------------------------------------------- #option Stepper_Port = PORTB 'Which PORT stepper is connected to #option Stepper_Pin1 = %00000001 '} #option Stepper_Pin2 = %00000010 '}Which 4 pins the stepper motor is #option Stepper_Pin3 = %00000100 '}connected to. (Pins 0-3 shown here) #option Stepper_Pin4 = %00001000 '} #option Stepper_FullStepSize = 750 'Degrees motor moves in one full step #option Stepper_HalfStepMode = True 'Drive motor in half step mode? #option Stepper_DefaultSpeed = 4 'Default delay in mS between steps #option Stepper_LimitSwitch = PORTB.4 'Pin which limit switch is connected 'to. Note: Active HIGH #option Stepper_TRIS = getTRIS(Stepper_Port) '=============================================================================== 'Variable and Const Declarations '------------------------------------------------------------------------------- '---Bring options into module Private Const #if Stepper_HalfStepMode Then StepJump = 1, StepSize = Stepper_FullStepSize / 2, #else StepJump = 2, StepSize = Stepper_FullStepSize, #endif Pin1 As Byte = Stepper_Pin1, Pin2 As Byte = Stepper_Pin2, Pin3 As Byte = Stepper_Pin3, Pin4 As Byte = Stepper_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 = Stepper_DefaultSpeed Private Dim StepperPort As Stepper_Port, LimitSwitch As Stepper_LimitSwitch.Stepper_LimitSwitch@, StepperTRIS As Stepper_TRIS '---Other Dims Private Dim CurrentStep As Byte Private Dim Position As Word Private Dim DistanceClockwise As Word Private Dim DistanceAntiClockwise As Word Private Dim StartingPosition As Word '=============================================================================== 'Helper Subs and Functions (Private - can't be called from main program) '------------------------------------------------------------------------------- Private Sub SingleStep(pRotateClockwise As Boolean) If pRotateClockwise Then CurrentStep = CurrentStep + StepJump Position = Position + StepSize If Position > 35999 Then Position = Position - 36000 EndIf Else CurrentStep = CurrentStep - StepJump 'Check for zero cross and update Position variable accordingly 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 '=============================================================================== 'Public Subs and Functions '------------------------------------------------------------------------------- '~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 'Name: Move 'Purpose: Moves stepper with specified direction, number of steps and speed '~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Public Sub Move(pRotateClockwise As Boolean = True, pNumberOfSteps As Word = 1, pSpeed As Byte = DefaultSpeed) While pNumberOfSteps > 0 SingleStep(pRotateClockwise) DelayMS(pSpeed) Dec(pNumberOfSteps) Wend 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. ' 'Returns: True if limit switch reached before pStepTimeout, ' False otherwise '~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Public Function MoveToLimit(pRotateClockwise As Boolean = True, pSpeed As Byte = DefaultSpeed, pStepTimeout As Word = 0) As Boolean If pStepTimeout > 0 Then 'Timeout has been specified While LimitSwitch = 0 And pStepTimeout > 0 SingleStep(pRotateClockwise) DelayMS(pSpeed) Dec(pStepTimeout) Wend If pStepTimeout = 0 Then result = False Else result = True EndIf Else 'No timeout specified While LimitSwitch = 0 SingleStep(pRotateClockwise) DelayMS(pSpeed) Wend result = True EndIf End Function '~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ '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. ' ' Note: All positions * 100 i.e. 90 deg = 9000 ' 'Returns: Actual final position of stepper. May vary from desired position ' due to resolution of step size. '~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Public Function MoveToPosition(pDesiredPosition As Word, pRotateClockwise As Boolean = True, pSpeed As Byte = DefaultSpeed) As Word 'If desired position is 360deg or over then bring it into 0 - 35999 range If pDesiredPosition > 35999 Then pDesiredPosition = pDesiredPosition - 36000 EndIf 'Keep making steps until the actual position is within 1/2 a step of the 'desired position (closest we can get). '2nd condition prevents problems caused around 360 / 0 degrees. 'i.e. without it then if desired position is 35999 and actual position is 0 'then the code will loop forever as Desired - Actual = 35999 While Math.abs(pDesiredPosition - Position) > StepSize / 2 And Math.abs(pDesiredPosition - Position) < 36000 - (StepSize / 2) SingleStep(pRotateClockwise) DelayMS(pSpeed) Wend result = Position End Function '~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 'Name: ShortestMoveToPosition 'Purpose: Moves stepper as close as possible to desired position with ' specified speed in the shortest direction. ' ' Note: All positions * 100 i.e. 90 deg = 9000 ' 'Returns: Actual final position of stepper. May vary from desired position ' due to resolution of step size. '~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Public Function ShortestMoveToPosition(pDesiredPosition As Word, pSpeed As Byte = DefaultSpeed) As Word '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 DistanceClockwise = pDesiredPosition - Position DistanceAntiClockwise = (36000 - pDesiredPosition) + Position Else DistanceClockwise = (36000 - Position) + pDesiredPosition DistanceAntiClockwise = Position - pDesiredPosition EndIf 'Call MoveToPosition function. Rotation direction determined by whether 'distance in clockwise direction is smaller than distance anticlockwise result = MoveToPosition(pDesiredPosition, DistanceClockwise < DistanceAntiClockwise, pSpeed) End Function '~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 'Name: Rotate 'Purpose: Rotates stepper the specified number of complete revolutions with ' specified direction and speed. '~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Public Sub Rotate(pNumberOfRotations As Byte = 1, pRotateClockwise As Boolean = True, pSpeed As Byte = DefaultSpeed) While pNumberOfRotations > 0 StartingPosition = Position SingleStep(pRotateClockwise) DelayMS(pSpeed) While Position <> StartingPosition SingleStep(pRotateClockwise) DelayMS(pSpeed) Wend Dec(pNumberofRotations) Wend End Sub '~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 'Name: PowerOff 'Purpose: Stops all output on stepper pins ' ' Note: Stepper won't hold position '~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Public Sub PowerOff() 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: 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 'Set TRIS without changing non-stepper pins StepperTRIS = StepperTRIS And PortMask