Sending again...

I will have a go ...

I am guessing from all I have read on the list that servo's are Pulse Width
Modulated.

You initially set the counter to zero, then turn portA.0 on.  The delay is
called and decs counter by 1 so result is 255.  So it continues to count
down to 0 and that's when it will return. (This may or may not be 1ms)

On returning you set the counter to 90 and call the delay.  (This delay
being 90/256  of the first delay) but the code does NOT turn off PortA.0
i.e. BCF Servo1 after the first Delay Call.  I think this is the problem for
Servo1.

To control Servo2 you will need to define as you have for Servo1 and then
add the instructions BSF Servo2 and BCF Servo2 in the right places.

To control them independently, well that's a little more involved.  You
could use inputs that when active you change the values that you put into
counter for the delays.  i.e. increment or decrement counter values as
required.

I hope this helps, I am reasonably new to this myself so I may be leading
you astray.

Justin

-----Original Message-----
From: Prince Anamalech [mailto:anamalech@HOTMAIL.COM]
Sent: Friday, 4 January 2002 15:06
To: PICLIST@MITVMA.MIT.EDU
Subject: [PIC]: My Servo code that i need help on plz?



Here is my servo code?

i am not sure how good it all is ? as i am new to mplab and assembly
language!

but i think i may have gone wrong with the servo updates somewhere? ??? :)

each servo is on porta.0 and port a.1 of my 16f84? but i have only written
some code for one servo? how do i implement two and get the code to work for
me? eg. backwards,forwards?

Below is the code!

Thankyou all in advance

anamalech

;"SmartBot Servo Test Program - Written By Anamalech"
INCLUDE "P16F84.INC"

BSF     STATUS,RP0         ;Set register bank 1
        CLRF    TRISA     ;Set All PORTA Pins to outputs

Counter         EQU     0Ch             ;Servo delay counter register
Position        EQU     0Dh             ;Servo Position register

#DEFINE  Servo1  PORTA,0  ;Defines Servo (A.0) I/O Pin on PIC16F84


Servo           MOVLW   0               ;Load Counter with # of cycles for
                MOVWF   Counter         ;1 ms Servo Delay
                BSF     Servo1          ;Activate the Servo output
                CALL    Delay           ;Wait for 1ms to pass
                MOVF    90,0         &nb! ! ! sp;  ;Load W with servo posi
tion
                                        ;00 & FF=extremes, 128=centre
                MOVWF   Counter         ;and store in Counter for next delay
                CALL    Delay           ;Keep servo active for position
delay
                GOTO Servo

Delay           ;Servo time delay
                NOP                     ;Pad the loop with one cycle
                DECFSZ  Counter         ;Counter=Counter-1
                GOTO    Delay           ;If Counter is not 0, repeat
                RETURN                  ;If 0, return

END














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