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Counting pulses at Timer0

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Shen Yi

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Count the number of pulses fed into the T0CKI pin, display the count on PORTB, and set the
RA3 bit when the count reaches the decimal value of 100. The count will be continuously displayed on PORTB after setting the RA3 bit.

using ASSEMBLY language
example:
movlw counter
movwf PORTB
.......
 
What PIC?
You can adapt this.
Max.

Code: 
;=======CCP_Tach.ASM====================================4/Sept/2015==
;
        list p=PIC18f23K22        ;list directive to define processor
        #include <p18f23K22.inc>    ;processor specific definitions


     ;Setup CONFIG1H
       CONFIG FOSC = HSHP, PLLCFG = OFF, PRICLKEN = OFF, FCMEN = OFF, IESO = OFF
     ;Setup CONFIG2L
     CONFIG PWRTEN = OFF, BOREN = OFF, BORV = 190
     ;Setup CONFIG2H
     CONFIG WDTEN = OFF, WDTPS = 1
     ;Setup CONFIG3H
     CONFIG MCLRE = EXTMCLR, CCP2MX = PORTB3, CCP3MX = PORTC6, HFOFST = OFF, T3CMX = PORTB5, P2BMX = PORTC0
     ;Setup CONFIG4L
     CONFIG STVREN = OFF, LVP = OFF, XINST = OFF
     ;Setup CONFIG5L
     CONFIG CP0 = OFF, CP1 = OFF             ;CP2 = OFF, CP3 = OFF
     ;Setup CONFIG5H
     CONFIG CPB = OFF, CPD = OFF
     ;Setup CONFIG6L
     CONFIG WRT0 = OFF, WRT1 = OFF            ;, WRT2 = OFF, WRT3 = OFF
     ;Setup CONFIG6H
     CONFIG WRTB = OFF, WRTC = OFF, WRTD = OFF
     ;Setup CONFIG7L
     CONFIG EBTR0 = OFF, EBTR1 = OFF        ;, EBTR2 = OFF, EBTR3 = OFF
     ;Setup CONFIG7H
     CONFIG EBTRB = OFF
       
;------------------------------------------------------------
; ------------------------------------------------------------
;------------------------------------------------------------
 ;This code executes when a reset occurs.

        ORG     0x0000        ;place code at reset vector

ResetCode:
        bra    Start        ;go to beginning of program

;----------------------------------------------------------------------------
;This code executes when a high priority interrupt occurs.

        ORG    0x0008        ;place code at interrupt vector


HighInt:
        bra    HighIntCode    ;go to high priority interrupt routine

;----------------------------------------------------------------------------
;This code executes when a low priority interrupt occurs.

        ORG    0x0018        ;place code at interrupt vector

LoIntCode:   
            goto iserv ;do interrupts here

        reset            ;error if no valid interrupt so reset
;---------------------------------------------------------
;High priority interrupt routine.

HighIntCode:
            retfie
;
Start:
            clrf    ANSELA
            clrf    ANSELB
            clrf    ANSELC
        ;    movlw    b'00000110' ;turn off A/D, port A
        ;    movwf    ADCON1
            movlw   b'00000000' ;port B outputs
           movwf    TRISB
            bsf        TRISC, 0     ;port C, bit 0 timer 1 input
            bsf        TRISC, CCP1  ;CCP1 pin input
        ;    movlw   b'00000000' ;port B lines low
            clrf     PORTB
            bcf        INTCON, GIE    ;disable global interrupts
            bcf        INTCON, PEIE    ;disable peripheral interrupts
            bcf        PIE1,TMR1IE    ;disable TMR1 interrupt
            bcf        PIE1,  CCP1IE    ;disable CCP1 interrupt
            bcf        PIR1, CCP1IF    ;clear CCP1 interrupt flag
            clrf    CCP1CON       ;CCP1 module off, clear CCP1 prescaler
            movlw    b'10000000' ;TMR1 prescaler and TMR1 setup,
            movwf    T1CON       ;  and TMR1 off
            clrf    TMR1H    ;clear timer 1 high
            clrf    TMR1L    ;clear timer 1 low, clear prescaler
            clrf    CCPR1H    ;clear capture register high
            clrf    CCPR1L    ;clear capture register low
            movlw    b'00000101' ;CCP1 prescaler mode,
            movwf    CCP1CON       ; CCP1 capture mode, CCP1 on
            bsf        INTCON, GIE    ;enable global interrupts
            bsf        INTCON, PEIE    ;enable peripheral interrupts
            bsf        T1CON, 0    ;timer 1 on
circle:
            goto    circle  ;done
;
iserv:
            bcf        PIR1, CCP1IF    ;clear ccp1 interrupt flag,
                    ;   enable further interrupts
            movf    CCPR1L, W    ;read capture register low
            movwf    PORTB    ;display captured count at port B
            retfie        ;return from interrupt
    ;
        end
;------------------------------------------------------------
;at device programming time, select:
;       memory unprotected
;       watchdog timer disabled (default is enabled)
;       standard crystal XT (using 4 MHz osc for test)
;       power-up timer on
;    brown-out reset enabled
;    lvp disabled
;    debug mode disabled
;============================================================
 
I don't believe the 16F84A has a CCP module. Edit: Oops, I connected Shen Li's two threads. He is using a 16F84A in the other thread. My assumption could be wrong.

You (Shen Yi) need to read Section 5 of the datasheet for that processor. The way you get an interrupt at some set point is to load the counter with (256 - <desired count>). Thus, the counter will rollover and create an interrupt after only the desired number of counts (e.g., 100) instead of 256 counts.

You will need to do the calculations for actual times, which may include considering a pre-scale, e.g, a prescale of 1:8 means that 8 signals only create one count on TMR0.

John
 
using PIC16F84A sorry forgot to mention, n btw some part of the code you just gave me i dont understand such as the PIR1, CPP1IF, CCP1CON stuff like dat (and many more)
but thx though
 
Here for an older version.
Max.
Code: 
;=======CAPT.ASM=====================================8/7/98==
        list    p=16c63
        radix   hex
;------------------------------------------------------------
;timer 1 and ccp1 module - capture mode demo
;------------------------------------------------------------
;       cpu equates (memory map)

;------------------------------------------------------------
;    bit equates
rp0    equ    5
ccp1    equ    2    ;ccp1 bit 2, port C
;------------------------------------------------------------
        org     0x000
    goto    start    ;skip over location pointed to by
            ;   interrupt vector
    org    0x004
    goto    iserv
;
start:
    bsf    status,rp0  ;switch to bank 1
    movlw   b'00000000' ;port B outputs
        movwf    trisb
    bsf    trisc,0     ;port C, bit 0 timer 1 input
    bsf    trisc,ccp1  ;ccp1 pin input
    bcf    status,rp0  ;switch back to bank 0
    movlw   b'00000000' ;port B lines low
    movwf    portb
    bcf    intcon,7    ;disable global interrupts
    bcf    intcon,6    ;disable peripheral interrupts
    bsf    status,rp0  ;bank 1
    bcf    pie1,0    ;disable tmr1 interrupt
    bcf    pie1,2    ;disable ccp1 interrupt
    bcf    status,rp0  ;bank 0
    bcf    pir1,2    ;clear ccp1 interrupt flag
    clrf    ccp1con       ;ccp1 module off, clear ccp1 prescaler
    movlw    b'00000010' ;tmr1 prescaler and tmr1 setup,
    movwf    t1con       ;   tmr1 off
    clrf    tmr1h    ;clear timer 1 high
    clrf    tmr1l    ;clear timer 1 low, clear prescaler
    clrf    ccpr1h    ;clear capture register high
    clrf    ccpr1l    ;clear capture register low
    movlw    b'00000101' ;ccp1 prescaler mode,
    movwf    ccp1con       ;   ccp1 capture mode, ccp1 on
    bsf    intcon,7    ;enable global interrupts
    bsf    intcon,6    ;enable peripheral interrupts
    bsf    status,rp0  ;bank 1
    bsf    pie1,2    ;enable ccp1 interrupt
    bcf    status,rp0  ;bank 0
    bsf    t1con,0    ;timer 1 on
circle:
  goto    circle  ;done
;
iserv:
    bcf    pir1,2    ;clear ccp1 interrupt flag,
            ;   enable further interrupts
    movf    ccpr1l,w    ;read capture register low
    movwf    portb    ;display captured count at port B
    retfie        ;return from interrupt
;
        end
;------------------------------------------------------------
 
sorry max, thx for the effort but too many things are completely different so i dont understand most parts of your code, FYI i am a complete beginner in programming, 1st time learning this subject
 
This is a very simple/easy program, this is the way you learn.
If you just use off the shelf code then there is no learning achieved.
Max.
 
Shen Yi said:
sorry max, thx for the effort but too many things are completely different so i dont understand most parts of your code, FYI i am a complete beginner in programming, 1st time learning this subject
Click to expand...
Then read the datasheet. Everything you need to know is in the section I mentioned. Of course, we haven't established whether you want to address your ignorance of writing code or are satisfied letting someone else write it for you.

John
 
sorry john but i desperately need the code as soon as possible and dont think i can complete my assignment even if i burn the midnight oil as i am doing right now
 
Ooops!!!

upload_2015-12-29_18-42-9.png
 
john i am desperate because i need the code to be complete in less than 12hours from now so am really sorry if i offended you for not doing my own work properly
 
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