Hi all

The literature is very misleading in its wording
I get everything else ok

I can handle the pre scaling and timing count of the timer as I want it to run as long as possible (about 3.8 times a second)

I'm wanting a continuous synchronous timer running on the internal 8 MHZ clock
I want it to trigger the interrupt at the end of its count.

What register set were

how
best regards,
Lex Dean

 

This is for 12F675 - check the banks of all the Special Function Registers as they tend to move around on different chips - hopefully the 724 isn't too different.
I've deleted all but the important stuff for the timer interrupt - on a 675 at 4MHz this gives 2 interrupts per second.

    list    p=12F675
    radix    hex
    title "sound"
        #include <p12f675.inc>
    __config _CP_OFF & _BODEN_OFF & _MCLRE_OFF & _PWRTE_OFF & _WDT_OFF & _INTRC_OSC_NOCLKOUT


    cblock 0x20
    W_TEMP
    STATUS_TEMP   
    endc
  
;    
;----------------------------------------------------------------------

    org    0x000
    goto init
    org 0x004    ;interrupt goes here
    MOVWF W_TEMP ; Copy W to TEMP register,
    SWAPF STATUS, W ; Swap status to be saved into W
    MOVWF STATUS_TEMP ; Save status to STATUS_TEMP register
    ;ISR : :
         ; Interrupt Service Routine

    
endint
     ; should configure Bank as required
     ;
    SWAPF STATUS_TEMP,W     ; Swap nibbles in STATUS_TEMP register
    ; and place result into W
    MOVWF STATUS             ; Move W into STATUS register
    ; (sets bank to original state)
    SWAPF W_TEMP, F         ; Swap nibbles in W_TEMP and place result in W_TEMP
    SWAPF W_TEMP, W         ; Swap nibbles in W_TEMP and place result into W
;    CLRF TMR1L                 ; Clear Low byte, Ensures no rollover into TMR1H
;    movlw 0xC0                ;set up timer1
;    movwf TMR1H
;    clrf TMR1L
    clrf INTCON                ;clr interupts
    bsf INTCON,PEIE            ;timer1 interrupt on
;    bsf INTCON, GPIE        ;gpio change interrupt on
    bcf PIR1, 0            ;clr tmr1 interrupt flag
    retfie
    
init    ;initialise stuff here
   
    movlw B'00110001'
    movwf T1CON                ;enable timer1 internal 1:8 prescaler 
    BSF STATUS, RP0 ; Bank 1
   
    bsf PIE1, 0                ;timer1 int enabled
;    BSF STATUS, RP0 ; Bank 1    
    clrf   OPTION_REG      ; 
    bcf     STATUS, RP0    ; bank 0    
    movlw   B'01000000'     ; enable timer 1 interrupt (not GIE yet)
    movwf   INTCON          ;  
    CLRF TMR1L                 ; Clear Low byte, Ensures no rollover into TMR1H
    clrf TMR1H
    
    bsf INTCON, GIE            ;enable interrupts, then sleep
  
main
   


    goto main

    end

 

Hay thanks
I can follow that

You made my day