How to add the Ultrasonic Distance robot skill
- Load the most recent release of ARC (Get ARC).
- Press the Project tab from the top menu bar in ARC.
- Press Add Robot Skill from the button ribbon bar in ARC.
- Choose the Ultrasonic Distance category tab.
- Press the Ultrasonic Distance icon to add the robot skill to your project.
Don't have a robot yet?
Follow the Getting Started Guide to build a robot and use the Ultrasonic Distance robot skill.
How to use the Ultrasonic Distance robot skill
Ultrasonic sensors use sonar (sound navigation ranging) to determine the distance to an object or wall, the same way some animals like bats and dolphins do. They offer excellent range and accuracy in an easy-to-use package. Unlike infrared sensors, their operation is not affected by sunlight or black materials. However, they have trouble with soft fabrics; the sonar echo works ideally when bouncing off hard surfaces.When an HC-SR04 or equivalent Ultrasonic Distance Sensor is connected to an EZB, this skill will display the distance of a detected object/wall in front of the sensor. This skill does not cause a robot to steer or avoid obstacles; it merely displays a distance value. For object avoidance and steering use the Radar skill.
This skill is integrated with scripting and will update when GetPing() is called (with matching port configured) and the PAUSE checkbox is checked. That way, you can have this skill on your project, but it won't use any communication resources unless it's called from a script with GetPing(). You can leave the PAUSED checkbox checked; this skill will be updated when GetPing() is called.
It's worth noting that the distance displayed is not a unit of CM or Inches. The distance value is an arbitrary number related to the sensor type, voltage, detected material, and temperature. If a specific distance unit is required, use a tape measure to identify the distance value.
Main Window

1. Ultrasonic Distance Value
This value between 0-255 corresponds to the detected distance sent by the ultrasonic sensor.
2. Bar Display
Displays a visual representation of the detected ultrasonic distance value.
3. Pause Checkbox
This checkbox pauses the capture of the ultrasonic distance value.
Settings

1. Title Field
This field contains the title of the skill. You can change it if you'd like. *Note: Changing the title will also change the title in the controlCommand() associated with this skill.
2. Board Index Drop-down
Select the EZB index number that your ultrasonic sensor is connected to.
3. Trigger & Echo Port Drop-downs
Select the digital port that your ultrasonic trigger wire is connected. Also, select the digital port that your ultrasonic echo wire is connected. *Note: This port must be the same as the trigger port when using a 3-wire Ultrasonic sensor.
4. Interval Drop-down
This drop-down selects the interval rate in milliseconds at which the ultrasonic sensor will be sampled. The range is 100-60000 milliseconds. The default setting is 250.
5. Variable & Multiplier
A variable will be set with the most recent distance value. This saves your code from calling GetPing, which adds needlessly to the communication channel.
The multiplier value will convert the raw distance value to a unit of measurement. For example, the default value of 1.25 will convert the distance into CM.
6. NMS (Navigation Messaging System)
The distance data can optionally be configured to push detected distances into the NMS (Level #3 Group #1) to be used by navigation robot skills, such as The Navigator. Please read the NMS manual and question marks associated with the options for better detail.
Wiring Diagram
Ultrasonic Distance Sensors come in 2 versions. A 4-wire type with/without an inline voltage regulator and three wires with/without a built-in voltage regulator. If an Ultrasonic has a voltage regulator, it will need +6V or greater Voltage input; if it doesn't, it will need +5V.

3-wire Wiring (with built-in regulator)
- Ground = Black wire to GND
- Power = Red wire to Vin
- Trigger/Echo = white wire to Digital pin
- Ground = Black wire from regulator to GND
- Power = Red wire from regulator to Vin
- Trigger = white wire to Digital pin
- Echo = green wire to a second Digital pin
Fix Resolution
If you use an EZ-Robot ultrasonic distance sensor, there may be false positives from the ping sound echoing within the casing. It is easy to fix with a few cotton balls inserted in the case around the sensors. Watch this video for detailed instructions.
Tech Details
Resources
Synthiam has a ultrasonic hardware reference design here.
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I'm guessing the microcontroller programmers of the knockoff sensors didn't know how to write the code efficiently. So their code takes too long to execute and blocks for >2ms.
While Arduino's "pulseIn()" on the Arduino EZB Firmware will wait up to 3 minutes, it would work with the knock-off sensors. However, I would not recommend it because the blocking time waiting for an echo will cause significant performance issues.
You're welcome. You'll get my bill.
Thomas
I do not work for EZ-Robot and can't speak on their response - but as a user like yourself, I would assume they would prefer you use their sensors for a positive experience because they guarantee they work. As you have experienced, many knock-off sensors are available that do not conform to the ping HC-SR04 standards.
you can by the sensor without the case 17 dollar .
sensor 17dollar
I got it. I guess I'll stick with my first solution of using the Arduino with Arduino code to monitor the sensors and then feed that to the EZ-B. I want to keep the EZ-B with my current project so that I can plug in a camera, output sound, and have all of those 24 digital I/O ports. Yes, I know I could use an Arduino Mega or some larger version of Arduino with a wireless camera and Bluetooth speakers.
Jeremie,
I suppose altering the EZ-B to allow the cheaper ping sensors would be a large & costly upgrade for EZ-Robot and probably out of the question. Yes?
Thomas
Here's what you need to know when purchasing HC-SR04 ultrasonics. All of the new style sensors are removing components to make more profit. It looks like the removal of these components causes these sensors to be slower (>2mS wait times per pulse). The older version sensors you want still have the load caps by the crystal and still have transistors on board.
If these components are missing you have a new and NOT-improved sensor.
It's not in my best interest to send you back to amazon, as we would love everyone to continue to support EZ-Robot with your hardware purchases, but I also don't like to be a gatekeeper so I'll say this: These sensors are still available online, I found some myself a few minutes ago that are $4CAD each, you have to wait a week to get them though.
Sorry Thomas, changing the EZ-Bv4 to support a sensor that we don't sell isn't in the cards.
Thank you!
@TMesserschmidt, I hope you write about that in one of the articles you author.
i agree with you . use parts that belong to a brand .
dj&jeremie well done masters .
I'll take a look for the ping sensors that Jeremie is suggesting.
Thanks to everyone who assisted with this issue.
Thomas
maybe you get a discount if you by 10 sensors from ez robot .:)
if you would by 10 random sensors , howmany arduino would you need to ,
get them all to work ?
thanks for the suggestion.
Thomas