I will give 5v input voltage in series with resister 320k ohm, resister 220 ohm, transistor 2N9015 connected to port 1.0 and a diode with the speaker. It is used with 8051 and some other things like LCD 20 x 4, keypad.

I just wonder how to make out square waves to make a sound? I really don't understand yet after searching from and read all posts about speaker. I have read the 8051 bible too. I still can't grase the concept.

I know i need to use timer/counter.

How to make a sound actually??

let say, if someone pressed the key pad, if will give a good sound. if someone had answered the wrong answer, it will give out a bad sound?

I wanna know how to control well to give out a sound in a suitable time.

Please help.