# A relatively dumb question...

How do I program an ultrasonic sensor with an analog input and convert it into digital so I can use it for programming?

Let’s say that the ultrasonic sensor is in port # 0 in the analog input part of the controller.

How would I set up the Ultrasonic class in a way that takes the analog port as the input.

Right now, it’s only giving me an error.

Could you post your code?

Alex Brinister

Use:

Then to get a reading:

ultrasonic.getVoltage();

Then you need to scale the voltage (0-5) to a distance, using a constant which should be in the documentation for the ultrasonic sensor.

How would I use that for the input and output?
This is our code.

AnalogOutput outUltra = new AnalogOutput(0);
inUltra.getVoltage();

Ultrasonic ultra = new Ultrasonic(0,0);
ultra.setAutomaticMode(true);
double range = ultra.getRangeInches();
String what = Double.toString(range);

for(int i = 1; i &lt; 10; i++){
SmartDashboard.putNumber(what, range);
}

You have to convert the voltage to a distance value. The sensor should have a spec for mV/in or mV/m or something relating voltage and distance.

For example, the MaxBotics MB1010 LV-EZ1 has a spec of 9.8mV/in with a 5V supply. So, if you read 0.392V from the sensor, this would result in a distance of 40 inches. (0.392 / 0.0098)

Some simple code you could use.

float voltage(0);
float distance(0);
const float volts_to_inches(0.0098);

voltage = ultrasonic.GetVoltage();
distance = voltage / volts_to_inches;

These sensors tend to be pretty noisy, so I would suggest a simple low pass filter.

const float filter_alpha = 0.5;

voltage = ultrasonic.GetVoltage();
distance = distance + filter_alpha * ((voltage / volts_to_inches) - distance);

Hope that helps!

EDIT: Didn’t realize this was in the Java forum and I wrote C++. Should still give you an idea of what to do.

What model ultrasonic sensor do you have? We use a Maxbotix sensor and there is an analog output pin. We don’t need an analog output, just analog in.

Also, you can also use this method to reduce noise.

ultraSonic.getAverageVoltage()