Using Vernier Sensors with the Hummingbird
Learn how to use Vernier sensors with the Hummingbird.
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Maker Tools, Science
Hummingbird kits contain sensors, but you can dramatically expand your measurement abilities by using the Hummingbird with sensor probes from Vernier. This page contains all the information that you will need to use selected Vernier sensors with the Hummingbird, but it does assume that you already know how to use Scratch or Snap!.
Vernier BTA Sensors
Analog Vernier sensors can be connected to the Hummingbird using the Vernier BTA Sensor Adapter. You can find a list of Vernier sensors here, and any sensor with an order code that ends in BTA is compatible with this adapter and can be used with the Hummingbird.
- To use a Vernier BTA sensor with the Hummingbird, first connect the Vernier BTA Sensor Adapter to a sensor port on the Hummingbird board.
- Next, connect the Vernier sensor to the adapter. In this tutorial, we will use the Vernier dual-range force sensor.
- Look through the documentation that came with your Vernier sensor. Find the section that gives the calibration parameters for the sensor. For most sensors, these will be a slope and an intercept. You can use these to create a linear function that relates the voltage of the sensor to units of the quantity that you are measuring. Here, we are using the force sensor with the ±10 N range. The slope is -4.9 N/V, and the intercept is 12.25 N. That means that we can use this equation to relate voltage to force in Newtons: force = -4.9*voltage + 12.25 N.
- We can also use this equation to find out the voltages that we should expect from the sensor. When the force is -10 N, the voltage is roughly 5 V (4.6 V). When the force is 10 N, the voltage is roughly 0 V (0.46 V). This means that we should expect voltages in the 0-5 V range. We set the jumper on the Vernier BTA sensor adapter to 0-5 V. Almost all Vernier BTA sensors will use the adapter with the jumper in this position. There are two exceptions, which are detailed in the Two Unusual Sensors section.
- Open Scratch or Snap!. In Scratch, you can use the HB voltage block to read the value of the sensor. This value will be a voltage between 0 and 5 V. In Snap!, you can use the Hummingbird Raw Sensor block. This block will give you a value from 0-100. To convert this value to voltage, you need to multiply it by 0.05.
- Declare a variable to hold the value that you are measuring. We have called our variable force. Use the calibration equation to convert the voltage to units of the quantity that you are measuring.
- Use a forever loop to update the value of the variable several times each second. Now, you are ready to graph the variable value on the screen or use it to control a robot!
Two Unusual Sensors
For most Vernier BTA sensors, the jumper on the adapter will be set to 0-5 V. The two exceptions are the voltage probe and the 30-Volt Voltage Probe. If you are using one of these sensors, place the jumper in the +10/-10 V position. Each of these sensors produces a voltage between -10 V and 10 V. The Vernier BTA Sensor Adapter includes a circuit that maps this voltage range to the 0-5 V range that the Hummingbird can read. You can use this equation to relate the Hummingbird voltage to the sensor voltage: sensor voltage = 4*Hummingbird voltage – 10.
You can incorporate a Vernier BTA sensor into a Hummingbird project as you would any other sensor. Alternatively, you can modify activities from the Vernier lab manuals to use the Hummingbird to collect data. Students can write programs to save this data in lists and plot it to the screen. In addition, these labs can be extended to include a building component. Two examples are given here.