In this article by Marco Schwartz and Oliver Manickum authors of the book Programming Arduino with LabVIEW, we will see how to design an interfave using LabVIEW.
(For more resources related to this topic, see here.)
At this stage, we know that we have our two sensors working and that they were interfaced correctly with the LabVIEW interface. However, we can do better; for now, we simply have a text display of the measurements, which is not elegant to read.
Also, the light-level measurement goes from 0 to 5, which doesn’t mean anything for somebody who will look at the interface for the first time.
Therefore, we will modify the interface slightly. We will add a temperature gauge to display the data coming from the temperature sensor, and we will modify the output of the reading from the photocell to display the measurement from 0 (no light) to 100 percent (maximum brightness).
We first need to place the different display elements. To do this, perform the following steps:
- Start with Front Panel. You can use a temperature gauge for the temperature and a simple slider indicator for Light Level. You will find both in the Indicators submenu of LabVIEW. After that, simply place them on the right-hand side of the interface and delete the other indicators we used earlier.
- Also, name the new indicators accordingly so that we can know to which element we have to connect them later.
Then, it is time to go back to Block Diagram to connect the new elements we just added in Front Panel. For the temperature element, it is easy: you can simply connect the temperature gauge to the TMP36 output pin.
For the light level, we will make slightly more complicated changes. We will divide the measured value beside the Analog Read element by 5, thus obtaining an output value between 0 and 1. Then, we will multiply this value by 100, to end up with a value going from 0 to 100 percent of the ambient light level.
To do so perform the following steps:
- The first step is to place two elements corresponding to the two mathematical operations we want to do: a divide operator and a multiply operator. You can find both of them in the Functions panel of LabVIEW. Simply place them close to the Analog Read element in your program.
- After that, right-click on one of the inputs of each operator element, and go to Create | Constant to create a constant input for each block. Add a value of 5 for the division block, and add a value of 100 for the multiply block.
- Finally, connect the output of the Analog Read element to the input of the division block, the output of this block to the input of the multiply block, and the output of the multiply block to the input of the Light Level indicator.
You can now go back to Front Panel to see the new interface in action. You can run the program again by clicking on the little arrow on the toolbar.
You should immediately see that Temperature is now indicated by the gauge on the right and Light Level is immediately changing on the slider, depending on how you cover the sensor with your hand.
Summary
In this article, we connected a temperature sensor and a light-level sensor to Arduino and built a simple LabVIEW program to read data from these sensors. Then, we built a nice graphical interface to visualize the data coming from these sensors.
There are many ways you can build other projects based on what you learned in this article. You can, for example, connect higher temperatures and/or more light-level sensors to the Arduino board and display these measurements in the interface. You can also connect other kinds of sensors that are supported by LabVIEW, for example, other analog sensors. For example, you can add a barometric pressure sensor or a humidity sensor to the project to build an even more complete weather-measurement station.
One other interesting extension of this article will be to use the storage and plotting capabilities of LabVIEW to dynamically plot the history of the measured data inside the LabVIEW interface.
Resources for Article:
Further resources on this subject:
- The Arduino Mobile Robot [article]
- Using the Leap Motion Controller with Arduino [article]
- Avoiding Obstacles Using Sensors [article]