Hi all.

i have a little circuit that i expect a 15 hz cycle, but it oscillate at 
about 3hz (eye-measured)

fosc = 4MHz (internal oscillator) so,
fosc / 4 = 1MHz
1MHz / 65536 = 15hz

what is wrong?, this is my first interrup circuit :( is fosc really 4 
MHz / 4 / 4 ??

thanks in advance

RVP

this is a mikrobasic code

dim counter as byte

sub procedure interrupt
    if PIR1.TMR1IF <> 0 then
     inc(counter)
     PIR1.TMR1IF = 0
   end if
end sub
 
main:

  while TRUE            ' Endless loop
    TRISB = 0           ' Configure pins of PORTB as output
    counter = 0 '
   
  INTCON = 0

  T1CON.T1CKPS1 = 0
  T1CON.T1CKPS0 = 0 ' preescaler 1:1

  T1CON.T1OSCEN = 0 ' osc shut down
  T1CON.NOT_T1SYNC = 1 ' not needed?

  T1CON.TMR1CS = 0 ' internal clock fosc/4
  T1CON.TMR1ON = 1 ' enable timer

  PIE1.TMR1IE = 1 ' enable overflow interrupt

  INTCON.PEIE = 1 ' enable peripheral interrupt
  INTCON.GIE = 1 ' enable global interrupt

    while true

      PORTB = counter

    wend
  wend





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