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How to Set Ultrasonic Sensor Range?

Published in Ultrasonic Sensor Thresholds 3 mins read

Setting the range of an ultrasonic sensor typically involves defining specific distance thresholds or zones within its operational capabilities using software, rather than physically adjusting the sensor itself. This allows you to trigger different actions based on how far an object is from the sensor.

Understanding Ultrasonic Sensor Range

Ultrasonic sensors have an inherent physical range (minimum to maximum distance they can detect). However, in practical projects, "setting the range" often refers to how you interpret the distance data received by the sensor in your code.

Defining Distance Thresholds in Software

The most common way to 'set' the range for specific actions is by establishing distance "buckets" or thresholds in your programming. This means you check if the measured distance falls within a certain range and then execute a corresponding action.

According to the reference, you should "Adjust your different distance threshold 'buckets' to a range suitable to your initial value."

Here’s how this works:

  1. Measure an initial distance: Get a baseline distance reading, perhaps the distance to an object in a starting position.
  2. Define threshold ranges: Based on this initial value and your application's needs, create distinct distance intervals.
  3. Write code to check distance: In your program, read the current distance from the sensor and compare it to your defined ranges.
  4. Trigger actions: Based on which range the distance falls into, perform a specific action (e.g., turn on an LED, sound an alarm, move a motor).

Example Thresholds

Let's use the example provided: "for instance if your hand was 60cm away, your ranges might be 60-40, 40-20, and 20-0."

This could be visualized as follows:

Distance Range (cm) Action Triggered (Example)
60 - 40 Turn on LED 1
40 - 20 Turn on LED 2 (or LED 1 & 2)
20 - 0 Turn on LED 3 (or All LEDs)

As the reference explains, if you "try moving in front of the sensor. As the distance shortens, you should see the LEDs turn on one by one." This demonstrates how setting these software-defined ranges allows for dynamic responses based on proximity.

Implementing Range Setting

Setting these ranges is done within the microcontroller or computer code that reads the sensor data. You will use conditional statements (like if, else if, else) to check the sensor's current distance reading against your desired thresholds.

  • Code Structure Idea:

    float distance_cm = readUltrasonicSensor(); // Get distance

if (distance_cm > 40 && distance_cm <= 60) {
    // Action for 60-40 cm range
    turnOnLed(1);
} else if (distance_cm > 20 && distance_cm <= 40) {
    // Action for 40-20 cm range
    turnOnLed(2);
} else if (distance_cm >= 0 && distance_cm <= 20) {
    // Action for 20-0 cm range
    turnOnLed(3);
} else {
    // Action for distances outside defined ranges (optional)
    turnOffAllLeds();
}

By adjusting these numerical thresholds in your code, you effectively "set" the ranges that are relevant to your specific application, allowing the sensor to interact meaningfully with its environment at different distances.

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