Stepper motor help

grasshopper

Would some one be kind enough to explain briefly how I can use a stepper motor with my propeller. I am having a hard time understanding a way to code it. I am using an Allegero A2919SB IC. Here is my schematic.

Joerg

After a short view to the data sheet, here a short comment:

P1 is turning ON/OFF the current of PHASE2 (0=ON, 1=OFF)
P2 steers the direction of the current for PHASE2 (0=positive, 1=negative)

P3 same as P1 but for PHASE1
P4 same as P2 but for PHASE1

P5 lowers the output current.

You have to do the timing like the diagram in the attachment shows. It depends how you will drive the motor:

- Halfstep (save method with no risk of oscillations)
- Fullstep
- 1 phase mode
- 2 phase mode

I hope this helps a bit

Saluti Joerg

grasshopper

Yes this helps a lot but i need some code to go off of as well.

Clemens

Check this out:
http://www.parallax.com/Resources/NutsVoltsColumns/NutsVoltsVolume7/tabid/450/Default.aspx
"Column #136: Stepping Out with Spin" is what you're looking for.

grasshopper

YES, that is what i was looking for. Nice write up Thanks

Joerg

OK here some code!

connect P1 to P0, P2 to P1, P3 to P2 and P3 to P2 (first p is your controller, the second your Propeller chip!)

connect P5 to GND (VSS) or open (the propeller chip is a 3.3V chip!!)

'stepper_A2919
{{MotStat
  Bit   7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |    State:  0         |  1   
        I   I   I   I   I   I   I   I------->      Stop      |  Run           
        I   I   I   I   I   I   I----------->      Forward   |  Backward
        I   I   I   I   I   I--------------->      Halfstep  |  Fullstep     not implemented yet
        I   I   I   I   I------------------->      SPhase    |  TPhase       not implemented yet
        I   I   I   I----------------------->      Continous |  Controled    not implemented yet
        I   I   I--------------------------->                NU
        I   I------------------------------->                NU
        I----------------------------------->                NU

Pin0   = P1
Pin0+1 = P2
Pin0+2 = P3
Pin0+3 = P4

P5 = VSS!!! (GND)

}}

VAR
  long  Stack[noparse][[/noparse]14]                     'Stack space for new cog
  byte  Cog                           'Hold ID of cog in use, if any
  byte  StepNr                        'the actual step number
  long  MCounter                      'counter to hold the waitcycles

CON
  Run = 1                             
  Backward = 2
  FullStep = 4
  TPhase = 8
  Synch = 128                   

PUB Start(Pin0,AdrMotStat, AdrStepTime): Success

  Stop
  Success := (Cog := cognew(ManageMotor(Pin0,AdrMotStat, AdrStepTime), @Stack) + 1)

PUB Stop
{{Stop toggling process, if any.}}

  if Cog
    cogstop(Cog~ - 1)

PUB ManageMotor(Pin0, AdrMotStat, AdrStepTime)

  StepNr~                                               'clear the StepNr counter
  dira[noparse][[/noparse]Pin0+7 .. Pin0]~~                                'sets the needed pins as output

  dira[noparse][[/noparse]16..23]~~
  
  repeat
    repeat until byte[noparse][[/noparse]AdrMotStat] & Run                 'wait until motor has to run!

    if byte[noparse][[/noparse]AdrMotStat] & Backward

      --StepNr                                          'backward
      if StepNr == 255
        StepNr := 7
   
    else
      ++StepNr                                          'foreward
      if StepNr > 7
        StepNr := 0    


    outa[noparse][[/noparse]Pin0+3 .. Pin0] := STEPTBL[noparse][[/noparse]StepNr]                  'set the outputs depending on the StepNr
    waitcnt(clkfreq / 1_000_000 * long[noparse][[/noparse]AdrStepTime]  + cnt)  'Wait for steptime cycles

     
      
DAT

STEPTBL       byte    4, 0, 1, 2, 6, 10, 9, 8       'table for controling the motor (halfsteps)

and a little program for testing your hardware:

{{MotionController2.spin}}

VAR
    long StepTime
    long ActPos
    long RefPos
    byte MotStat
    byte SynchControl

    byte Pin0

OBJ
  Motion : "Stepper_A2919"


PUB Main

  StepTime := 100_000
  MotStat := 0
  Pin0 := 0
''  dira[noparse][[/noparse]16..19]~~

  Motion.Start(Pin0,@MotStat,@StepTime)

  repeat
    if ina[noparse][[/noparse]11..8] == 14
      MotStat := 1
    elseif ina[noparse][[/noparse]11..8] == 12
      MotStat := 3  
    else
      MotStat := 0

I hope it works

Saluti Joerg

grasshopper

Thanks for the code example. I almost have it working now.