Using #int_timer2 to on/off buzzer

[rrb011270]

Mabuhay!

I have a problem with the code below... it would not generate a monotone on my buzzer.. anybody in the forum who can check and review my code.. I plan to generate a 100Hz monotone using interrupt timer2 at PortA4 of PIC18F452.

The code listed below:

Code:

#include <18F452.h>              // Target PIC Microcontroller IC #device  *=16                    // use a 16-bit pointer #device ICD=TRUE #fuses HS,NOPROTECT,NOWDT        // PIC MCU Configuration #use delay(clock=20000000)       // 20MHz Crystal clock speed //********************************************************************** // Configure PortA4 for buzzer output #bit BuzzBIT=0xF80.4 const int tones[] = { 70,74,76,83,88,94,99,105,112,118,126,133,141 }; int tone_reqd; //********************************************************************** #int_timer2 void tick(void) {    static int tick;    static int toggle;    if (tick) --tick;    else {       tick=tones[tone_reqd];       toggle^=1;       BuzzBIT=toggle;    } } //********************************************************************** main() {    setup_timer_2(T2_DIV_BY_4,40,1);    enable_interrupts(int_timer2);    enable_interrupts(global);    tone_reqd=1;    while (1) ; }

I'll appreciate any help.

Thank you.

[Mark]

Didn't look at your code, but RA4 stands out. That is the first thing I look for when the hardware guys do designed. They always forget to add a pullup. Refer to the datasheet if you are trying to drive some device. You will need to add a pullup resistor or tie one pin of the buzzer to 5V.

[Mark]

It also look like your frequecy is around 156Hz.

20000000/4 = 5000000 = internal clock
5000000/4 = 1250000 = timer2 increments
1250000/(256-40) = 5787 = timer2 interrupts
5787/74 = 78 is the 1/2 frequecy

Now I am not sure what you are trying to drive, but I don't think it is a subwoofer That sounds like too low a frequency. Most piezo's are in the KHz.

[rrb011270]