Hi all,

i am facing problem on interfacing hardware to ports.
i want to beep a buzzer in equal intervals.

i have used a transistor to switch a buzzer through µC. as soon as i switch ON the system, the buzzer beeps and switches OFF.

the program is as follows,

org 0000h
clr 90h ; the buzzer is connected to this bit
i have cleared this bit coz i do not want this to beep at this instant.

loop: acall delay ; delay for 500ms.routine
not shown here

setb 90h ; ON the buzzer
acall delay

clr 90h

sjmp loop

end
the problem is as soon as i switch ON the system, the buzzer beeps for a small time.
i want to avoid this.
i have given clr 90h at the beginning itself to avoid this, but still the problem is not solved. please help me.

i have connected RC network between the emitter of another transistor (emitter is connected to the ground). the resistor(10K) is connected to 5volts DC and to the base of transistor. a cap of 1000µF/25V between base and ground, such that the ground is isolated untill the cap charges and takes some time to switch the transistor to ground.