Variable tone circuit

[Steve2381]

Anyone got any ideas for a circuit to control a variable bleep/tone output?
I don't want to use FREQ as it halts the routine (and trashes my running numeral LED display), yet I need to play at least 5 different pitch warning tones - basically just using a brief pulse output.

I could make 5 individual tone circuits, but that ties up 5 I/O lines.

Thanks

Steve
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[Lee Harker]

Steve,
You could use a 555 timer circuit arranged in astable mode to create the tones. You could use a digital pot to set the frequency and a seperate pin could be used to enable the circuit with the reset pin. It is also possible if you pick your values right that you may be able to delete the enable line. You could adjust the value of the digital pot so the output of the 555 is outside the audio range.
It would probalby take just a few milliseconds to change the tone frequency.

Lee

[Steve2381]

Yes... I thought of using a 555 chip.
I think its going to be a case of playing around for an evening on my breadboard and seeing what I can come up with.