I'm almost 99% sure that the signal runs from 0Vdc to 5Vdc. Tomorrow morning, when I am back in my school's lab, I will verify that this is completely true.
For some background, I am attempting to write software for the Parallax Inc.
PING))) sonar sensor. The pulse width of it's response corresponds to the distance between itself and an object.
Currently, I am using bench top equipment to operate the PING))). A function generator triggers the PING))) to measure and an oscilliscope measures the returning pulse width. The sensor is accurate wthin an inch. At only $25, this sensor looks very exciting for FIRST applications.
The difficulty in this project is the mini-RC signal pin will be both an output and input. I have been able to trigger the sensor from the RC. Unfortunately, the mini-rc hasn't been capable of reading the response.
By simulating a response from the sonar sensor using the function generator I am hoping to isolate the problem in my code.