The Stepper motor need to pulse low at the data pin (i used the stepper that used 4 pin data). and the Vcc have two pins. the procedure is like this...
1. to move right or left just follow the direction of the data pins
example :
to move right :
data1-----data2-----data3----data4
0 --------- 1 -------- 1 -------- 1----->(15 degree)
1 --------- 0 -------- 1 -------- 1----->(30 degree)
1 --------- 1 -------- 0 -------- 1----->(45 degree)
to move left:
data1-----data2-----data3----data4
1 --------- 1 --------- 1 ------- 0----->(15 degree)
1 --------- 1 --------- 0 ------- 1----->(30 degree)
1 --------- 0 --------- 1 ------- 1----->(45 degree)
and so on...
using assembly language, here some example
mov p1,#0ffh ; set the default value to 1
clr p1.0 ; 15 degree move to left
mov a, p1
rl a
mov p1,a ;move again 15 degree left
rl a
mov p1, a ; move again 15 degree left