Slow speed tachometer

[richard]

a few thoughts :-
1, INTCON.7 "GIE" and INTCON.6 "PEIE" probably need to be set

2, this piece of code can never execute because its orphaned

RESUME ' Return to main program
ENABLE ' Enable interrupts


TMPlowbyte = 0 ' Variable reset
PIR1.0=0 ' Reset TMR1's Interupt Flag
TMR1Overflow = 0 ' Reset TMR1 Overflow counter


END ' End of program


3, the " on interrupt " latency is variable and unpredictable and is unlikey to give accurate results.
dt interrupts is vastly better.

4, for your purposes rpm measurement using "pulsin" is far simpler to do and a lot easier to get working.

[fpeixeiro]

Thanks Richard

I'm going to explain myself better.

My goal is to use timer0 to refresh the 7 segment displays, and use timer1 free running so i can count the pulses from portb.7 so i think setting interrupts for timer1 won't be nedded. The part that captures TMR1L and calculates RPM, is the one that is giving me problems.

Can you explain me better the part of tho orphaned code?

From what i have read, and correct me if i'm wrong, since i'm trying to aquire a signal near 0.625hz, those command won't serve my purposes.

There is one thing that i'm going to try is to use a 32.768 Khz crystal, my doubt is can i use as a primary crystal or do i have to connect it to RB6 and RB7?

Because i'm running out os pins, i'm setting on another breadboard the same schematic, but with a 16f877a.

Thanks.