Sound generating with an AVR
Unless you are almost just using headphones, you will not be able to drive anything from the pin on the micro controller. You will want an amplifier of some sort. Are you using PWM to create the sound? If so you can just use a single transistor and pullup resistor (First Circuit). Otherwise you really want a push pull style amplifier (Second Circuit) and you will need some biasing and more DC blocking. I would recommend searching a bit a bout amplifiers in that case. Also you really want a capacitor in series with the speaker to remove any DC current that would flow. This is critically important for the Single transistor model.







simulate this circuit &ndash; Schematic created using CircuitLab

NOTE: These schematics are just examples, the values and transistors used may or may not be appropriate for your setup.