Can I wire up two ultrasonic piezos to an arduino and reproduce a ping sensor? I doubt i could do that directly without the use of the circuitry involved with the ping, but just curious...
I've got two piezos i salvaged from a toy that my son destroyed (can't wait for him to destroy a couple more toys. Some of his toys are cooler than mine!)
You'd need to drive it through a transistor, at least. Piezo sensors have significant capacitance so could have a large inrush current when you turn them on. Perhaps you could address that with a series resistor. However, the piezo will also generate positive and negative voltages due to mechanical knocks and sounds impacting it, and the microcontroller won't like negative voltages or positive voltages over 5V on any of its pins. So as a speaker I think you want to drive it through a transistor, and as a microphone I think you want to use it to trigger a transistor to amplify the signal to a level the microntroller can read, and to constrain the peak values of that signal.
You will need a minimal amount of circuitry to pull this off. You might try going
to the maxbotix site and downloading the d/s for one of their EZ sonars, where
you will see the schematic for the unit.