Waveforms

Read more about the article Producing Waveforms using Wave Generator module in the PSLab Android App

Producing Waveforms using Wave Generator module in the PSLab Android App

This blog will demonstrate how to produce different waveforms using the Wave Generator module in the PSLab android app and view them on the Oscilloscope. The Wave Generator in PSLab android app is simple to use and has a UI which is similar to physical commodity wave generators. It is capable of producing different waveforms like sine, sawtooth and square wave. Apparatus Required Before getting started with the wave generator we require the following items: PSLab device An android phone with PSLab app installed in it. USB cable (Mini B) OTG(On the Go) wire Some connecting wires having pins at both ends Understanding the Wave Generator Pins Let me briefly explain the use of the pins that are going to be used in the Wave generator module: S1 and S2 pins The PSLab device contains two pins (S1, S2) which are capable of producing two independent analog waveforms (sine,  sawtooth) having different frequencies and phase offset. The frequency range is from 10Hz to 5Khz. SQR1, SQR2, SQR3 and SQR4 pin The SQR1 pin is used for producing the square waveform and all the SQ pins can be used together to produce four different PWM signal having the same frequency. These PWM signal can have a different duty cycle and phase. CH1, CH2 and CH3 pin The CH pins are used by the oscilloscope in the  PSLab android app to monitor waveform signals produced by the wave generator pins. They can be used together to simultaneously monitor multiple waveforms. Setting up the Device We need to connect the PSLab device with the mobile phone as shown in Figure 2 which can be done by following steps: Connect a micro USB(Mini B) to the PSLab device. Connect the other end of the micro USB cable to the OTG. Connect the OTG to the phone. Producing Waveforms Now, once the device has been properly connected to the device (which is shown at the top right corner of the app), then in the instruments page scroll down to the Wave Generator card and click on it to open the WaveGenerator activity. Here you will see a screen like shown in Figure 4 containing two monitors and a controlling panel with lots of buttons. Here the Waveform panel is used to control the S1 and S2 pins whose properties are shown on the left monitor screen and the Digital panel is used to control the SQR pins whose properties are shown on the right monitor screen. For sine/sawtooth wave: Connect the S1 pin to the CH1 pin using a connecting wire, then in the Waveform panel select the Wave1 button, choose the type of waveform(either sine or sawtooth), then click on the Freq button to change the frequency of the wave, then use the Seek bar or the up/down arrow buttons to change the value of frequency and then press the set button to set the frequency for the S1 pin as shown below: Now, click the view button at bottom right corner, this will directly…

Continue ReadingProducing Waveforms using Wave Generator module in the PSLab Android App
Read more about the article Coloring Waveforms in PSLab Charts

Coloring Waveforms in PSLab Charts

Charts are used to display set of data in an analytical manner such that an observer can easily come to a conclusion by just looking at it without having to go through all the numerical data sets. Legends are used to differentiate a set of data set from another set. Generally, different colors and different names are used to form a legend in a chart. MPAndroidChart is an amazing library with the capability of generating different types of graphs in an Android device. In PSLab several user interfaces are implemented using LineCharts to display different waveforms such as readings from channels attached to PSLab device, logic levels etc. When several data sets are being plotted on the same graph area, legends are used. In PSLab Android application, Oscilloscope supports four different type of waveforms to be plotted on the same graph. Logic Analyzer implements one to four different types of logic level waveforms on the same plot. To identify which is which, legends with different colors can be used rather than just the names. For the legends to have different colors, it should be explicitly set which color should be held by which data set. Otherwise it will use the default color to all the legends making it hard to differentiate data lines when there are more than one data set is plotted. Assume a data set is generated from a reading taken from a probe attached to PSLab device. The set will be added as an Entry to an array list as follows; ArrayList<Entry> dataSet = new ArrayList<Entry>(); The next step will be to create a Line Data Set LineDataSet lineData = new LineDataSet(dataSet, "DataSet 1"); This LineDataSet will contain sample values of the waveform captured by the microprocessor. A LineDataSet object support many methods to alter its look and feel. In order to set a color for the legend, setColor() method will be useful. This method accepts an integer as the color. This method can be accessed as follows; lineData.setColor(Color.YELLOW); MPAndroidChart provides different sets of colors under ColorTemplate. This class has several predefined colors with five colors in each color palette are added by the developers of the library and they can be accessed using the following line of code by simply calling the index value of the palette array list. set1.setColor(ColorTemplate.JOYFUL_COLORS[0]); Set of color palettes available in the ColorTemplate class are; LIBERTY_COLORS JOYFUL_COLORS PASTEL_COLORS COLORFUL_COLORS VORDIPLOM_COLORS MATERIAL_COLORS The following demonstrates how the above activities produce a line chart with three different data sets with different colored legends. This implementation can be used to enhance the readability of the waveforms letting user being able to differentiate between one waveform from another in PSLab Android application. Resources: MPAndroidChart Repository: https://github.com/PhilJay/MPAndroidChart Line Charts: https://en.wikipedia.org/wiki/Line_chart MPAndroidChart Line Chart Tutorial: https://www.numetriclabz.com/android-line-chart-using-mpandroidchart-tutorial/ MPAndroidChart Legends tutorial: https://www.studytutorial.in/android-line-chart-or-line-graph-using-mpandroid-library-tutorial PSLab official web site: https://pslab.fossasia.org/

Continue ReadingColoring Waveforms in PSLab Charts