In SX Microcontrollers, SX/B Compiler and SX-Key Tool, Peter Van der Zee wrote:

Hi Bebop;

You are wiggling the port bit by alternately making it an input and then an output. That is not the correct way to do things. Write your code to make port ra.1 an output only once, and the make that output alternately be high or low. There are many ways to accomplish that, one simple way (not the best way) is included.


SetDir  mov    m,#$0f                ;set mode to access tris direction registers
           mov    w,#%1111_1101  ;port bit 1
           mov    !ra,w                   ;make port ra.1 be an output, all others remain input

Waves  setb    ra.1                    ;set port a.1 high
            mov    w,#$10               ;delay value
            mov    Delay,w              ;load the delay counter
Delay1  decsz  Delay                 ;loop until
            jmp     Delay1               ;delay is done
            nop                              ;time adjust for end of cycle "jump"
            nop                              ;time adjust for end of cycle "jump"
            nop                              ;time adjust for end of cycle "jump"
            clrb     ra.1                    ;reset port a.1
            mov    w,#$10               ;delay value
            mov    Delay,w              ;load the delay counter; can be same variable as before because only one is running at a time
Delay2  decsz  Delay                 ;loop until
            jmp     Delay2               ;delay is done
            jmp     Waves                ;the jump consumes 3 instruction cycles


Hope this helps.

Cheers,

Peter (pjv)

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