Step motor control

[dragan77]

HI,
do you now what is hapend,
when I write this code:

Delay VAR BYTE
i VAR WORD

TRISB = 0 ' All outputs.

Delay = 10 ' ~100steps / second

For i = 1 to 512
PORTB = %00000001
Pause Delay
PORTB = %00000010
Pause Delay
PORTB = %00000100
Pause Delay
PORTB = %00001000
Pause Delay

NEXT

Pause 1500

For i = 1 to 512
PORTB = %00001000
Pause Delay
PORTB = %00000100
Pause Delay
PORTB = %00000010
Pause Delay
PORTB = %00000001
Pause Delay
NEXT

My motor turn round 360 degrees, and back - 360 degrees ,1 time!!!

and when I write this code:

Delay VAR BYTE
i VAR WORD

TRISB = 0 ' All outputs.

Delay = 10 ' ~100steps / second

For i = 1 to 4096
PORTB = %00000001
Pause Delay
PORTB = %00000010
Pause Delay
PORTB = %00000100
Pause Delay
PORTB = %00001000
Pause Delay

NEXT

Pause 1500

For i = 1 to 4096
PORTB = %00001000
Pause Delay
PORTB = %00000100
Pause Delay
PORTB = %00000010
Pause Delay
PORTB = %00000001
Pause Delay
NEXT

my motor turn round 360 degrees,and back - 360 degrees, 4 time is correct?

[dragan77]

this is schema:

[HenrikOlsson]

Hi,
Yes, if the motor/gearbox requires 4096 steps to turn one revolution the first piece of code will move 360 degrees forward and then 360 degrees back. There are 4 "steps" each time thru the FOR-NEXT loop so 512*4=4096.

In the second piece of code it'll move 1440 degrees forward and then 1440 degrees back.

[dragan77]

thks,but sorry I don't understood,is not problem to write code to I tested,pls.

[dragan77]

Can you looking this page,
my motor is ST-28.MAYBE YOU FIND ANSWER!
http://www.khwelling.nl/cnc/hardware/motor_test.html

[aratti]

You can improve your motor performance in two ways:

1) Use half step sequence ( here a sample code)

HStep           var byte    [8]     ' Half step sequence array
B0              var byte
C0              var byte
P0              var byte
W0              var word

TRISB = 0


P0 = 50   ' incrementing the delay will reduce the motor speed  (max 255)
C0 = 0
B0 = 0

HalfMode:                      
If C0 = 0 then gosub CW
C0 = C0 + 1
if C0 = 2 then C0 = 0
If C0 = 0 then gosub CW
If C0 = 1 then gosub CCW

for W0 = 0 to 8192   ' one turn of the gear shaft ( 64 motor turns)
PortB = HStep[B0]
B0 = B0+1   
if B0 = 8 then B0=0
pause P0
next W0

Goto HalfMode

CW:        ' half step sequence (clockwise)
HStep[0] = 1
HStep[1] = 3
HStep[2] = 2
HStep[3] = 6
HStep[4] = 4
HStep[5] = 12
HStep[6] = 8
HStep[7] = 9
return

CCW:       ' half step sequence (counter clockwise)
HStep[0] = 9
HStep[1] = 8
HStep[2] = 12
HStep[3] = 4
HStep[4] = 6
HStep[5] = 2
HStep[6] = 3
HStep[7] = 1
return

end

2) Use a constant current setup to your motor. The simple way is to use a LM317 configured as costant current supply. See the attached schematic (Resistor 33 Ohms 1 watt. Use 24 V dc as an input to the LM317)

cheers

Al.

[dragan77]

Thks,all for help!!!
I tired testing all code,I hope I do something!
Just one question,
Is possible make some code in picbasic,

When I start step motor,to start every time to one position,
example:

If step motor work some,go to left,go to right,.......
and I stop power,and turn again,is possible,motor back in some start position,and continue work some function!