piezo buzzer connection

[jo12345]

how do i connect the piezo buzzer in my circuit? i hav attached the circuit diagram. its a quiz buzzer.this is a circuit i am mounting on a pcb. the seven segment display works properly and gives me the output. the problem with the circuit is that the piezo buzzer does not work in the circuit though it is in a working condition. one terminal of the piezo buzzer is connected to the pin 32 of AT89C51 and the other to +5V. do i need to connect any capacitor?
please do reply...
thank you

 

[ark5230]

The program will reveal details.

 

[jo12345]

program

#include<reg51.h>
unsigned int digi_val[10]={0x40,0xF9,0x24,0x30,0x19,0x12,0x02,0xF8,0x00,0x10};        // Hex value corresponding to the digits 0 to 9
sbit output_on_pin = P3^0;        // Enable pin to enable the seven segment.
sbit stop_pin = P3^1;        // Stop pin to reset the buzzer.
sbit buzzer_pin=P0^0;        //  Buzzer pin to sound the buzzer.
int flag;	

void delay()        // Time delay function
{
    int i,j;
    for(i=0;i<200;i++)
    for(j=0;j<1275;j++);
}

void display(unsigned int current_dig)        // Function to display the resultant digit on the seven segment and sound the buzzer.
{
    P2=digi_val[current_dig];
    output_on_pin = 1;
    buzzer_pin=0;
    delay();
    buzzer_pin=1;
    while(stop_pin != 0);
}  

void buzzer() //Function to monitor the input switches
{
    flag = 0;
    while(1)
    {
        while (P1 == 0xFF);
        
        while (P1 == 0xFE)        //Check if switch 1 is pressed
        {
            flag = 1;
            display(1);
        }

        while (P1 == 0xFD)        //Check if switch 2 is pressed
        {
            flag = 2;
            display(2);
        }    

        while (P1 == 0xFB )        //Check if switch 3 is pressed
        {
            flag = 3;
            display(3);
        }

        while (P1 == 0xF7 )        //Check if switch 4 is pressed
        {
            flag = 4;
            display(4);
        }

        while (P1 == 0xEF )        //Check if switch 5 is pressed
        {
            flag = 5;
            display(5);
        }

        while (P1 == 0xDF)        //Check if switch 6 is pressed
        {
            flag = 6;
            display(6);
        }

        while (P1 == 0xBF )        //Check if switch 7 is pressed
        {
            flag = 7;
            display(7);
        }

        while (P1 == 0x7F )        //Check if switch 8 is pressed
        {
            flag = 8;
            display(8);
        }
      
        P1 = 0xFF;
        stop_pin = 1;
        output_on_pin = 0;
    }
}

void main()
{
    output_on_pin=0;
    stop_pin = 1;
    P1 = 0xFF;
    buzzer();

}

 

[diegotheslinger]

The peizo works hooking it up straight to the 5v supply? Maybe you need a transistor in there to suplement some of the current if the micro can't source/sink it by itself?

 

[jo12345]

how do i do that?

 

[jo12345]

please reply.... its urgent

 

[diegotheslinger]

Well I would check and make sure the piezo itself is working. The one I have is rated for 5v so simply connect the positive side to 5v and the negative to ground. It should produce a sound. If that works than there is probably something wrong with your program or original wiring.

 

[jo12345]

i had already checked the buzzer. it was working perfectly fine. i am unable to understand the problem with the circuit