In SX Microcontrollers, SX/B Compiler and SX-Key Tool, Staryi wrote:

This show the bug without debugger. RA.0 stay high when debug is detected. Used internal RC-oscillator at 32 kHz
[code]
; Demonstrate the inc/dec bug without debugger
; Need one LED connected from RA.0 to GND 
; (whis current limiter resistor, of course)
; When right work, must be one short LED flash after reset
; When this bug occur, the LED stay light.
; Use internal clock oscillator at 32 kHz. 

  

DEVICE  SX48,OSC32KHZ
IRC_CAL IRC_SLOW 

  

RESET start
 

  

        org 0x0a
R0      ds 1 ; checked counter
R1      ds 1 ; cycle counter 


  

        org 0
; Interrupt service routine (dummy)
        nop
        nop
        reti 

  

start   page main
        jmp main 


  

  

main
        mov W,#0x1f  ; DDIR_W mode
        mov M,W  ;
        Mov !RA,#11111110b ; RA.0 for output
        Mov RA,#1  ; The LED is light
        Mov RTCC,#19
        Mov !option,#10001000b ; RTCC start
        jmp @Work 

  

        org 0x800
; The critically routine
Work
        nop
        clr R0
        Mov R1,#200
:loop   nop
        nop
        inc R0
        djnz R1,:loop
        mov W,#200  ; Check R0 value (here must be 200)
        xor W,R0  ; Is equal?
        snz   ; Skip if not equal
         clrb RA.0  ; Switch off LED, if equal (bug not detected)
; If not equal, the LED stay light (bug detected)
:q      nop
        jmp :q  ; The end (empty unlimited loop) 

 end
 
[/code]

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