Re: Like the idea, but...
blah, blah, I could do that with a 555...
Yeah, you could. You'd have to do more calculations, breadboard or solder up more components and then tune the vibrator to the frequency you need.
Or just grab the Arduino off the shelf, plug it in and get going, doing the tuning in the programming.
Is it overkill? Probably. But it's convenient and Arduino's are cheap as chips compared to spending even an hour extra time building an discrete square wave generator.
Look at it this way. In the olden days a square wave would be generated with discrete components, transistors, resistors, capacitors, diodes, etc (talk about unnecessary complexity...). Then we got the 555 timer chip to combine all those components in silicon and require less discrete components. Now we have MCU's in various guises to fulfill the job even easier and with more flexibility.