I'm looking for the simplest way to generate audio tones. Something like a square or sine wave, but I want multiple tone options. For example, two quick beeps, one at 440Hz, one at 1Khz. The tones should occur at the press of a button, and again at the release.
I am aware that a square wave can be generated with a 555 timer, but I don't know how to produce multiple tones. I also know a simple microcontroller can be used with a DAC, but I have a few requirements:
- Parts count and cost as low as possible. Under $1 in higher quantities of components is ideal.
- The components must not require FCC certification or SDoC, which is a concern going the microcontroller route.
- The audio signal must be a mic-level signal.
Is some kind of MCU unavoidable in this situation? I've yet to find a suitable solution that covers all those bases, so any help is greatly appreciated!