incrementing up to ... then reset - Electronic Circuits Projects Diagrams Free

johnl69 · 13th November 2008, 07:46 PM

Hi

I cant seem to work out how to increment a registry value from 0 to 24 and then have this registry reset to 0 and to display this on a lcd screen.

What im trying to do is to enter a time into a pic to be compared for an alarm, the problem I have is as I press the button to increment the time the display goes from 0 - 9 then through the whole ascii code.

Any help would be appreciated

john

Henry T · 13th November 2008, 07:50 PM

What language are you programming it in and wich pic?
But you have to convert your HEX code to a BCD code, there are examples galore of that around here I bet.

johnl69 · 13th November 2008, 08:00 PM

Sorry I forgot to put I right in assembly and pic 16f877

I can do the bcd to hex conversion but my problem is getting the value to stop at 24 and then reset to 0 at the next button press

Henry T · 13th November 2008, 08:10 PM

Euhm, long time since I worked in asm for pics, but do they have a compare function?
Or else you could decrement a register every time you increment and when that hits 0 you can do whatever... BTFSZ i believe that was?

picasm · 13th November 2008, 09:51 PM

To reset the count back to zero if "reg" increments higher than 24:

Code:

 
    incf    reg,F               ;Inc the reg
    movlw    D'25'            ;load with 25 to check against reg
    xorwf    reg,W            ;Xor but dont affect the reg yet
    btfsc    STATUS,Z       ;Skip if not 25
    clrf    reg                   ;Reached 25 so set reg back to 0
    movf    reg,W            ;Get the new value of reg into w to send to your display

Henry T · 13th November 2008, 10:05 PM

btfsC it was appearantly

xor'ing it will work too I guess, and then when they are equal, the Z flag gets cleared or something? Pff i need to get back into my PicASM, it's all 8051 at our school now, and there are WAYY too many instructions, wich is nice too mind you, but a risc is a little different eh :d

Pommie · 13th November 2008, 11:20 PM

Shouldn't you be counting from 0 to 23 or 1 to 24. Counting from 0 to 24 will result in a 25 hour day!!

Mike.

johnl69 · 14th November 2008, 08:25 PM

Thanks alot guys for your help,

Pommie, Yes it should be 0 - 23 and then 0 - 59 but it was late and I was still feeling the effects from the anastetic

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13th November 2008, 07:46 PM	#1
johnl69	incrementing up to ... then reset Hi I cant seem to work out how to increment a registry value from 0 to 24 and then have this registry reset to 0 and to display this on a lcd screen. What im trying to do is to enter a time into a pic to be compared for an alarm, the problem I have is as I press the button to increment the time the display goes from 0 - 9 then through the whole ascii code. Any help would be appreciated john

13th November 2008, 07:50 PM	#2
Henry T	What language are you programming it in and wich pic? But you have to convert your HEX code to a BCD code, there are examples galore of that around here I bet. __________________ There are no stupid questions, but PLEASE, think twice before asking them

13th November 2008, 08:00 PM	#3
johnl69	Sorry I forgot to put I right in assembly and pic 16f877 I can do the bcd to hex conversion but my problem is getting the value to stop at 24 and then reset to 0 at the next button press Last edited by johnl69; 13th November 2008 at 08:05 PM.

13th November 2008, 08:10 PM	#4
Henry T	Euhm, long time since I worked in asm for pics, but do they have a compare function? Or else you could decrement a register every time you increment and when that hits 0 you can do whatever... BTFSZ i believe that was? __________________ There are no stupid questions, but PLEASE, think twice before asking them

13th November 2008, 10:05 PM	#6
Henry T	btfsC it was appearantly xor'ing it will work too I guess, and then when they are equal, the Z flag gets cleared or something? Pff i need to get back into my PicASM, it's all 8051 at our school now, and there are WAYY too many instructions, wich is nice too mind you, but a risc is a little different eh :d __________________ There are no stupid questions, but PLEASE, think twice before asking them

13th November 2008, 11:20 PM	#7
Pommie	Shouldn't you be counting from 0 to 23 or 1 to 24. Counting from 0 to 24 will result in a 25 hour day!! Mike.

14th November 2008, 08:25 PM	#8
johnl69	Thanks alot guys for your help, Pommie, Yes it should be 0 - 23 and then 0 - 59 but it was late and I was still feeling the effects from the anastetic