Hi,

I currently have a servo with rated specification 0.6ms to 2.2ms for 0 to 180 deg @ 20ms.

Now this is the PWM code (servopwm.txt) I wrote for a 45 degree angle; but the servo motor always goes to a random angle ~ 150 deg (and keeps vibrating there). I am using an AT89S52.

ORG 000H
START: SJMP START1
ORG 050H
START1:
BACK:  
        ACALL _45DEG          
        SJMP BACK             

_45DEG:  SETB P1.0
        MOV R2, #22             ;22 cycles for 1ms
_ABC1:  NOP                    
        NOP                   
        DJNZ R2, _ABC1        
        CLR P1.0
        ACALL DELAY_20MS       
        RET                    
DELAY_20MS: MOV R0,#4607     ;4607 cycles for 20 ms             
_ABCD:  NOP
        NOP
        DJNZ R0, _ABCD
        RET

 

Kindly let me know what the error could be.
I am using an external 4.91V power supply.
Also, how can I control multiple servos on Port 1? (I have to individually control 8 servos)

Thanks in advance