Post by thread:Beginners problem

Hello everyone! I recieved my first 16F84 chip few days ago, and I made a simple testboard with RC oscillator and 8 LEDs connected to each pin of PORTB. Then I wrote a little program with PASM to flash leds. delay mov ax,#200 jump1 mov bx,#200 jump2 dec bx mov W,bx jnz jump2 dec ax mov W,ax jnz jump1 ret loop1 mov portb, cx add cx,cx call delay mov portb, #0 call delay jmp loop1 ret This should flash each led in PORTB, but it doesn't. When 'cx' reaches value 32 (led in pin 11 flashes), the program sets 'cx' again to value 1. So the program flashes only leds in pins 6-11. I'm not a big genious in ASM coding and I've no idea what I've done wrong. That quite terrible increment delay seems to be working fine. Help me please! -MParvikko

> Van: MadDog Parvikko <spam_OUTparvikkoTakeThisOuTSGIC.FI> > Aan: .....PICLISTKILLspam@spam@MITVMA.MIT.EDU > Onderwerp: Beginners problem > Datum: woensdag 8 april 1998 19:13 > > Hello everyone! > I recieved my first 16F84 chip few days ago, and I made a simple > testboard with RC oscillator and 8 LEDs connected to each pin of > PORTB. Then I wrote a little program with PASM to flash leds. > delay mov ax,#200 > jump1 mov bx,#200 > jump2 dec bx > mov W,bx > jnz jump2 > dec ax > mov W,ax > jnz jump1 > ret The combination : dec {reg} mov w,{reg} jnz *** could be written like : decfsz {reg} goto *** (that is, in standard Micro-Chip assembler - Freeware !) The shortest (memory usage :-) ) delay loop I know goes like this : clrf DelayH clrf DelayH Delay: decfsz DelayL goto Delay decfsz DelayH goto Delay return (Again, in standard Micro-Chip assembler) > loop1 mov portb, cx > add cx,cx > call delay > mov portb, #0 > call delay > jmp loop1 > ret Apart from the initialisation of Port B and register CX it looks fine to me. Did you define where you wanted to store your 'registers' (ax,bx,cx) ? They should be at 0x0C, 0x0D and 0x0E for your example. > This should flash each led in PORTB, but it doesn't. When 'cx' reaches > value 32 (led in pin 11 flashes), the program sets 'cx' again to value 1. > So the program flashes only leds in pins 6-11. I'm not a big genious > in ASM coding and I've no idea what I've done wrong. That quite terrible > increment delay seems to be working fine. Help me please! If you would send your Hex-code (the code generated as output by your assembler), I could debug that. If you do, send it _DIRECTLY_ to caissonKILLspamtelebyte.nl , so we don't clobber this mailing-list. > -MParvikko Greetz, Rudy wieser

Hi Caisson (Caisson), in <.....199804091053.MAA05694KILLspam.....degas.telebyte.nl> on Apr 9 you wrote: > The shortest (memory usage :-) ) delay loop I know goes like this : > clrf DelayH > clrf DelayH > Delay: > decfsz DelayL > goto Delay > decfsz DelayH > goto Delay > return You can save a register file: clrf DelayH clrw Delay: addlw 1 btfsc STATUS,Z decfsz DelayH,f goto Delay return :-) Isn't that cute? - only one goto statement

> Van: Marc Heuler <EraseMEmarcspam_OUTTakeThisOuTAARGH.MAYN.DE> > Aan: PICLISTspam_OUTMITVMA.MIT.EDU > Onderwerp: Re: Beginners problem > Datum: donderdag 9 april 1998 21:42 > > Hi Caisson (Caisson), in <@spam@199804091053.MAA05694KILLspamdegas.telebyte.nl> on Apr 9 you > wrote: [Cut] {Quote hidden}> You can save a register file: > > clrf DelayH > clrw > Delay: addlw 1 > btfsc STATUS,Z > decfsz DelayH,f > goto Delay > return > > :-) Isn't that cute? - only one goto statement Yeah !! That's why I like this 'discussion list' so much ! There is allways someone with a better/other solution & willing to share. Thanks Marc. It will be put into my 'snippets' directory. Greetz, Rudy Wieser