28BY J-48 bibolar stepper driver full wave at every 2ms

[stan cartwright]

Hi.I got several 28BY J-48 bibolar stepper motors cheap on ebay and they are popular cos they are cheap
but they need pulsing with 4 phases every 2ms to rotate at max torque.
So this is a mega328p UNO solution.
I got the 1ms timer 0 demo and the timer calculator and got the values for 2ms,easy.
It uses vars forward,stop,reverse to control the motors.
The demo shows the motors running while wait command.
It is just a handler for these cheap geared stepper motors.
https://www.youtube.com/watch?v=0eZFZsmpvR4&feature=youtu.be

;28BY J-48 bibolar stepper driver full wave at every 2ms
;this uses portD for 2 motors
#chip mega328p,16
#option Explicit

dim l_mot_pos,r_mot_pos as byte
dim l_mot_dir,r_mot_dir as byte

#define forward 1   ;|
#define reverse 255 ;|--motor direction
#define stop 0      ;|

l_mot_pos=1:r_mot_pos=1
l_mot_dir=forward:r_mot_dir=forward
;
;setup stepper motor interrupts step every 2ms
    On Interrupt Timer0Match1 Call motors
    Dim OCR0  AS byte alias OCR0A
    Dim TCCR0 AS  byte alias TCCR0B
    WGM01 = 1                'Timer in CTC mode - required
    'Timer0 Prescaler = 64
    OCR0 = 124 ;2ms
    TCCR0 = 0x28
    TCCR0 = TCCR0 or 0x04
;
do
l_mot_dir=forward:r_mot_dir=forward
wait 5 s
l_mot_dir=reverse:r_mot_dir=reverse
wait 5 s
l_mot_dir=reverse:r_mot_dir=forward
wait 5 s
l_mot_dir=forward:r_mot_dir=reverse
wait 5 s
loop

sub motors
  if l_mot_dir=stop then
    set portd.0 off:set portd.1 off:set portd.2 off:set portd.3 off
  else if l_mot_dir=forward then
    l_mot_pos++
    if l_mot_pos=5 then
      l_mot_pos=1
    end if
  else
    l_mot_pos---
    if l_mot_pos=0 then
      l_mot_pos=4
    end if
  end if
;
  select case l_mot_pos
    case 1
      set portd.0 on:set portd.1 on:set portd.2 off:set portd.3 off
    case 2
      set portd.0 off:set portd.1 on:set portd.2 on:set portd.3 off
    case 3
      set portd.0 off:set portd.1 off:set portd.2 on:set portd.3 on
    case 4
      set portd.0 on:set portd.1 off:set portd.2 off:set portd.3 on
  end select
;
  if r_mot_dir=stop then
    set portd.4 off:set portd.5 off:set portd.6 off:set portd.7 off
  else if r_mot_dir=forward then
    r_mot_pos++
    if r_mot_pos=5 then
      r_mot_pos=1
    end if
  else
    r_mot_pos---
    if r_mot_pos=0 then
      r_mot_pos=4
    end if
  end if
;
 select case r_mot_pos
  case 1
    set portd.4 on:set portd.5 off:set portd.6 off:set portd.7 on
  case 2
    set portd.4 off:set portd.5 off:set portd.6 on:set portd.7 on
  case 3
    set portd.4 off:set portd.5 on:set portd.6 on:set portd.7 off
  case 4
    set portd.4 on:set portd.5 on:set portd.6 off:set portd.7 off
 end select
end sub

[mmotte]

Hi Stan,
Here's mine.

'28BYJ_48_12F683_ver092.gcb
'2017/ 1/ 3
'A program to Run a 4096 step geared step motor 28BYJ-48
'actually this is doing full step mode in which 2 coils are active at a Time
' so it only has 2048 steps/turn (seems like a couple less)
'Another array could be built to do eight half steps
'The outputs run a ULN2003 like supplied by so many chinese suppliers
'The input Port GPIO.4 has a pushbutton
'Setup: routine allows the operator to align the shaft on start up
'MainLoop: routine rotates the motor one full turn
'If you change the MainLoop in line 44 to MainLoop2 then it
'will demo a 5 station/position pattern
'by Mike Otte
'2013

'Chip model
#chip 12F683, 8

  dim Full(5)
      Full(0) = b'00000110'
      Full(1) = b'00000011'
      Full(2) = b'00001001'
      Full(3) = b'00001100'

'Set the pin directions
dir GPIO.0 out  'These are  wired to the uln2003 inputs
dir GPIO.1 out
dir GPIO.2 out
dir GPIO.5 out

dir GPIO.4 IN   'pushbutton input

Dim position as Word  'Could be integer if we go below 0 position
position =0

'Initialize position routine
Setup:
  ' let motor turn until operator Pushes Button at home Position
  If GPIO.4 = 1 Then StepCW
  'wait for button push
  If GPIO.4 = 0 Then
    position =0
    wait 500 ms
    goto MainLoop2  ' to demo 5 position
  end if
  goto Setup

'One turn MainLoop ,get here from 3 lines above ,line44?
MainLoop:
  'wait for button push
  If GPIO.4 = 1 Then goto MainLoop

  StepTo(2040)  'one turn

  position =0   'resets position counter for next move
  wait 500 ms   'Gives time for button release if only a few steps

 goto MainLoop

' Example2: of going to 5 different positions and waiting for the button to be pushed
'Button is a pull down
MainLoop2:
  If GPIO.4 = 1 Then goto MainLoop2
  If GPIO.4 = 0 Then
    station++
    If station > 5 then station = 1

    wait 500 ms
    goto newstation
  end if
  goto MainLoop2
newstation:
  Select case station
    case 1
        StepTo(500) 'station position 1
        wait 500 ms   'Gives time for button release if only a few steps
    case 2
        StepTo(1500)  'station position 2
        wait 500 ms   'Gives time for button release if only a few steps
    case 3
        StepTo(2500)  'station position 3
        wait 500 ms   'Gives time for button release if only a few steps
    case 4
        StepTo(3000)  'station position 4
        wait 500 ms   'Gives time for button release if only a few steps
    case 5
        StepTo(3100)  'station position 5
        wait 500 ms   'Gives time for button release if only a few steps
    end Select
 goto MainLoop2

Sub StepTo(newpos as word)
    EnMotor
   Do until Position = newpos
    If newpos < position then StepCCW

    If newpos > position then StepCW

   loop
   DisEnMotor
end sub

Sub EnMotor
  dir GPIO.0 out
  dir GPIO.1 out
  dir GPIO.2 out
  dir GPIO.5 out
end sub

Sub DisEnMotor
  dir GPIO.0 in 'disables motor so it converves energy and don't heat up
  dir GPIO.1 in
  dir GPIO.2 in
  dir GPIO.5 in
end sub

Sub StepCW
    Position++
    myStep = position mod 4
    thisStep = Full(myStep)
    GPIO.0 = thisStep.0
    GPIO.1 = thisStep.1
    GPIO.2 = thisStep.2
    GPIO.5 = thisStep.3
    wait 2 ms
end sub

Sub StepCCW
    Position--
    myStep = position mod 4
    thisStep = Full(myStep)
    GPIO.0 = thisStep.0
    GPIO.1 = thisStep.1
    GPIO.2 = thisStep.2
    GPIO.5 = thisStep.3
    wait 2 ms
end sub

End

[stan cartwright]

Hi Mike. These geared steppers and drivers seem popular,loads of youtube and guides.
I posted code for running them before but used a i2c port expander. I think running that and a i2c rangefinder would do my head.
As before I used an interrupt so the motors run at a constant most efficient speed.
Seems they can be run with halfwave,fullwave or a combo of both. Fullwave is simple and faster. Before I used the combo mode which is 8 different phases, more steps so slower rotation.
2ms is optimum rotation time. Any faster and they don't turn.

[stan cartwright]

mike
I send off to each port

Sub DisEnMotor
  dir GPIO.0 in 'disables motor so it converves energy and don't heat up
  dir GPIO.1 in
  dir GPIO.2 in
  dir GPIO.5 in
end sub

does gcb have portx=255 so you can set all bit in one go?
I don't think so or it would be easy to control these motors by just rotating the phase pattern left/right.
only 4 bits so 1 byte does 2 motors ie the port.
it would be portd= left phase + right phase * 8
if using 4 bits for each motor,

[mmotte]

Hi Stan,
Here's another.
Astro photography require to move the camera as the Earth turns so you do not get "star trails". So a "Barn Door" tracker was built. Hinge on one end of two boards and a threaded rod turned by a motor on the other end. Mount the camera on the top board and screw the bottom board to a tripod. Then align the hinge pivot to the north star thus making a primative "equatorial mount". I did this with my Cannon 1000 and a 300 mm lens. Took some great pictures.

'A program to Run a 4096 step geared step motor on a 10-32 threaded rod 
' for a "barn Door" tracker to hold a camera and track the stars
'by Mike Otte
'2013

'Chip model
#chip 16F886, 8

  dim Full(5)
      Full(0) = b'00000110'
      Full(1) = b'00000011'
      Full(2) = b'00001001'
      Full(3) = b'00001100'

dim   RFull(5)
      RFull(3) = b'00000110'
      RFull(2) = b'00000011'
      RFull(1) = b'00001001'
      RFull(0) = b'00001100'

' momentary switches
#define Home PORTC.0
#define RAstop PORTC.1
#define RAplus PORTC.2
#define limit PORTC.3
'define PORTC upper 4 bits for adjusting the time in additional millisec / step

'Set the pin directions
dir PORTB out
dir PORTC IN
' i am not using interrupt because this steps fast 
'On Interrupt PORTBChange Call buttons


 wttm = 17    'wait time was 25 msec
 wtmodify= PORTC
 wtmodify = wtmodify AND 0xf0  ' mask off the upper four bits
  rotate wtmodify right simple  'shift them to the lower four bits
  rotate wtmodify right simple  ' i put pullups and board jumper pins to act as switches
  rotate wtmodify right simple
  rotate wtmodify right simple
  wttm = wttm + wtmodify        ' add or subtract for tuning delay from portc upper four bits
' wttm (wait time) now has the total value
   PortB = 0          'initialize
  myj=0
 wait 1 s
'Main routine

Start:
        myStep = myj mod 4
      thisStep = Full(myStep)

        PortB = thisStep 

        wait wttm ms
      myj++
        gosub  buttons

goto Start

sub buttons
  if RAplus = 0 then    ' these were going to make it go faster or slower 

    DO UNTIL RAplus = 1
    myStep = myj mod 4
      PortB =  Full(myStep)
      wait  7 ms
    myj++
    loop    
  end if

  if RAstop = 0 then   ' but i don't use these two switches

    DO UNTIL RAstop = 1
    myStep = myj mod 4
      PortB =  RFull(myStep)
      wait  7 ms
    myj++
    loop
  end if

   if home = 0 then     'I really only use these two switches
                '"home" switch sends the barn door towards home (closed limit)
    DO UNTIL limit = 0   ' the "limit"  stops it when it get home 
    myStep = myj mod 4   'and returns it to going forward again
       PortB =  RFull(myStep)
       wait  2 ms
    myj++
    loop
  end if


End Sub 

Pretty much only used the Battery switch, run switch and the limit switch.

[stan cartwright]

New to me. https://nyxtech.us/products/nyx-tracker

[mmotte]

That's it. mine is less refined and inexpensive.

[mmotte]

That's it. mine is less refined and inexpensive.