We have the Parallax Ping))) sensor. It has 3 pins, but the constructor for digitalUltrasonic requires two unique numbers for the ping and echo channel. We thought we could beat this by using a Y-cable on the output line to plug it into two ports, but that didn’t appear to work, do we need a custom class written to send start signal and one to listen for return signal? Does anyone have example code for this?
I’ve never seen RIO code for this, only Arduino. The key thing is that you have to switch the data pin from being a digital output (relatively low impedance) to trigger the ping, then to a digital input (high impedance) to receive the return. In arduino, this is changing the mode of the pin. In WPIlib you may have to re-instantiate two objects each ping cycle.
Edit: Sorry, I thought the below had been working with a Y-splitter, but after testing again it doesn’t seem to be working as expected.
I fiddled with one over the holidays. Seems to work fine with the Ultrasonic class.
import edu.wpi.first.wpilibj.Ultrasonic; Ultrasonic _pingSonar; _pingSonar = new Ultrasonic(0, 1); _pingSonar.setAutomaticMode(true); double range = _pingSonar.getRangeInches();
I used this Arduino code before hooking up to the RIO.
How did you wire it? The constructor uses both pins 0 and 1, but the sensor only has one data pin.
I was wondering this myself. We tried to use a Y-splitter on the cable, but that didn’t give us any values.
The problem with just y-splitting is that the trigger pin holds the return pin low when you’re trying to get the output. Perhaps you could put a diode on the trigger pin so it can send a high pulse but not a low one? Not sure how the sensor is biased.
Good question. I thought I had used a Y-splitter, but I just dug up the sensor again and tried my test code from December, and it’s not working. I swear I had it working before. I tried every wiring and constructor arrangement I could think, but no go. Possibly something changed in the Ultrasonic class, but just as likely I’m crazy and I only ever got it to work with the Arduino. Sorry for the confusion.