TMR0 Pre Scale Question

[Bruce]

Yep. So with a 16-bit timer, 1:1 prescaler, 20MHz osc, it will count up & roll-over in
200nS * 65,536, which = ~13.1mS.

If you can live with a few uS short of 1 second, then you can change the prescaler
to 1:256, and do something like this;

    DEFINE OSC 20
    TMR0_FLAG VAR INTCON.2  ' Timer0 over-flow flag bit
    
    TMR0H = $B3       ' $B3B5 = 46,005
    TMR0L = $B5
    TMR0_FLAG = 0     ' clear TMR0 over-flow flag
    T0CON = %10000111 ' 16-bit, 1:256 prescale, TMR0 ON
    
Main:
    REPEAT            ' just loop waiting for over-flow flag
      @ NOP
    UNTIL TMR0_FLAG = 1
    
    TMR0_FLAG = 0     ' clear over-flow flag
    TMR0H = $B3       ' reload for 1 second over-flow
    TMR0L = $B5
    TOGGLE PORTB.0
    
    GOTO Main

Works out to roughly 0.999 seconds per toggle.