Author: harsh-2711

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Read more about the article Working with Logic Analyzer in PSLab application

Working with Logic Analyzer in PSLab application

This blog demonstrates the working of Logic Analyzer instrument available in PSLab Desktop Application. It also includes a detailed description of the features available in the Logic Analyzer instrument. Also, it provides a step by step guide on how to work with the Logic Analyzer provided by PSLab which will be beneficial to first-time users. What is a Logic Analyzer? A Logic Analyzer is an electronic instrument used to capture and display digital signals with an added functionality of providing the time difference between different edges of different pulses. It is mainly used to observe the time relationship between different digital signals. An example of a standard Logic Analyzer available in the market is as shown in figure 1. Figure 1. Standard Logic Analyzer How to generate different digital pulses in PSLab? Logic Analyzer needs to be provided with some input of digital pulses among whom time relationship is to be found out. Digital pulses generated from different systems can be directly provided as input to the logic analyzer for analyzing. But PSLab provides a functionality to generate digital pulses up to some constrained frequency. Following are the steps to generate different digital waves in the PSLab desktop application : Go to Advanced Control Section of PSLab app. The screen should look like one as shown in Figure 2. Figure 2.  Advanced Control Section PSLab device provides generation of maximum four digital waves at once. In this example, I will proceed by utilizing all the four pins i.e. SQR1, SQR2, SQR3, SQR4 (where SQR = Acronym of square wave generator and the number next to it is the pin ID available on the PSLab device). Set the duty cycles for each of the pins as desired (try to keep all the duty cycles different from each other to understand the process of measurement easily). After setting it should look something like Figure 3. Figure 3. Configuring PWM NOTE: User can also set phase angle for different waves but I will proceed keeping all without any phase difference. Now set the frequency of the digital waves in the tab provided next to text Frequency and then press the SET button. This should generate desired digital waves when connected. How to analyze the generated waves in Logic Analyzer? Now go to the Experiments section and click on the Logic Analyzer instrument as shown in Figure 4. Figure 4. Test and Measurement Page Now a screen as shown in Figure 5 should open which is the main screen for Logic Analyzer Instrument. Figure 5. Logic Analyzer Main Page On the right, you can see three buttons i.e Start, Plot Data and Raw Data. Below that selection for the number of channels is provided. And at last, the time measurement tool is provided which can measure the time difference between different edges of different digital waves. The graph at the center is the place where all the waves generated will be plotted. Now as we have generated four different waves, we need to navigate to…

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Read more about the article Implementing Card View in PSLab app

Implementing Card View in PSLab app

Card View was announced by Google in I/O ‘14 conference. Although it started a bit slow, but now we can see most of the apps like Snapchat, Google, Facebook, etc. using this widget. So, this blog is solely contributed on how to implement Card View in your own app by taking example of PSLab application. What is Card View ? CardView is a view container or ViewGroup that inherits its nature from FrameLayout which further inherits from ViewGroup itself. The only thing that separates a CardView from any other ViewGroups is its nature to behave like a card, more specifically the shadow and rounded corners. The basic customization that a CardView provides includes CornerRadius, Elevation, MaxElevation, ContentPadding, CompatPadding, PreventCornerOverlap, and a dedicated CardBackgroundColor or say Card Background which is the most necessary feature for a card to look cool. Step by Step description how CardView was implemented in PSLab First step is to add dependencies in your project as widgets like Card View, Recyclerview, etc. are not included in a common repository of widgets provided by Google. App level dependency : compile 'com.android.support:cardview-v7:26.0.0' compile 'com.android.support:recyclerview-v7:+' If you are using Android Studio 3.0+ than add the following dependency instead of above : implementation 'com.android.support:cardview-v7:26.0.0' implementation 'com.android.support:recyclerview-v7:27.1.1'  Now we can use Card View widget in our app. So, first make add card view in layout section like this : <android.support.v7.widget.CardView android:id="@+id/card_view" android:layout_width="match_parent" android:layout_height="@dimen/total_height_card" android:layout_gravity="center" android:layout_margin="@dimen/card_margin" card_view:cardCornerRadius="@dimen/card_radius"> </android.support.v7.widget.CardView> These are the basic attributes that are used while declaring a card view. Other possible attributes can be : Elevation - Used to elevate card to give a depth effect MaxElevation - Used to give constraint to the depth effect ContentPadding - Used to provide padding between content and the card PreventCornerOverlap - To prevent different corners to overlap as shown in figure 1. Figure 1. Image showing corner overlapping in CardView Now to set the objects inside the Card View, mostly RelativeLayout is preferred as it gives the freedom to place objects in reference of others whereas LinearLayout provides freedom to place them in only one direction. Other layouts such as FrameLayout, Tables, etc. can be used as per the need of the app. Now we will create a layout that will hold all the cards using RecyclerView. <android.support.v7.widget.RecyclerView android:id="@+id/recycler_view" android:scrollbars="vertical" android:layout_width="match_parent" android:layout_height="wrap_content"/> Now after setting the layouts, it's time to make adapter which inflates the information in the cards which is then represented using RecyclerView. public class ApplicationAdapter extends RecyclerView.Adapter<ApplicationAdapter.Holder> { private List<ApplicationItem> applicationList; private final OnItemClickListener listener; /** * View holder for application list item */ public class Holder extends RecyclerView.ViewHolder { TextView header, description; ImageView applicationIcon; //Background Image public Holder(View itemView) { super(itemView); this.header = itemView.findViewById(R.id.heading_card); this.description = itemView.findViewById(R.id.description_card); this.applicationIcon = itemView.findViewById(R.id.application_icon); } public void setup(final ApplicationItem applicationItem, final OnItemClickListener listener) { header.setText(applicationItem.getApplicationName()); description.setText(applicationItem.getApplicationDescription()); applicationIcon.setImageResource(applicationItem.getApplicationIcon()); } } public ApplicationAdapter(Context mContext, List<ApplicationItem> applicationList, OnItemClickListener listener) { this.mContext = mContext; this.applicationList = applicationList; this.listener = listener; } @Override public Holder onCreateViewHolder(ViewGroup parent, int viewType) { View itemView = LayoutInflater.from(parent.getContext()) .inflate(R.layout.application_list_item, parent, false); return…

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Read more about the article Implementing Leak Canary in PSLab Android App

Implementing Leak Canary in PSLab Android App

This post discusses the issue of memory leaks and how to handle them efficiently and what are the tools available which help developers in managing the memory leaks. After working on PR #824 opened under PSLab - Android repository I have got a greater idea about how to manage the memory efficiently and what are the tools that should be used to ease the work. What are memory leaks and how it affects the quality of app? In simple words, memory leaks happen when you hold on to an item for long after its purpose have been served. It is as simple as that. But let us dive in further to understand more about this topic. Programming languages like C and C++ need memory management done by user whereas in higher level languages like Java, Python, etc. low-level memory management and garbage collection is done automatically by the system. But it is due to programming faults that memory leaks happen and so care needs to be taken with higher level languages too in handling memory efficiently. In Android or say in any OS (operating system), every item has to be destroyed or say deleted or freed from the memory after its purpose is served. But if the reference of this object is passed on to any other object which has a greater time of importance than this, then it will try to hold this object for long and so the garbage collector won’t be able to collect it and so there will be memory leaks in the code. This is how memory leaks occurs inside an app. Now, the issue of memory leaks is utmost important among developers as due to it, the app becomes slow, laggy, eats up a lot of memory and the app crashes after some time of use which creates a very bad user experience. As the user keeps on using the app, the heap memory also keeps on increasing and due to memory leaks, this heap can’t be freed by the garbage collector. Thus, all these issues contribute to making the threads or processes running inside the app slower and it can result in a lag of time from microseconds to milliseconds too!! How can you detect these memory leaks? This blog is mostly for Android developers and so I will use the environment of Android Studio for reference. For controlling memory leaks, Android Studio has a very powerful tool named Monitors. There are individual monitors not only for memory usage but for CPU, GPU, and network usage as well. An example of it is shown in figure 1 below. Figure 1. Monitor in Android Studio Now how to observe the graphs that are produced by Monitors to see if there are any memory leaks? The first alarming case is when the memory usage graph constantly increases and doesn’t come down as time passes and even not decreases when you put the app in the background. The tools which are used to undo memory leaks…

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Read more about the article Implementing search bar in PSLab app

Implementing search bar in PSLab app

PSLab offers a large range of functions with a large field of applications. This results in the long access path to certain information and functionality in the app, which affects the user experience (UX) negatively. In this blog post, I will show how the UX in Android applications with many functions can be improved by implementing a ‘Search Bar’. Further, I have created a screencast that follows the step-by-step description shown in this blog post [1]. Search Bar is the functionality which can be seen nowadays in almost all the apps. It is a handy widget for users to navigate the app. PSLab's Android app was lacking this functionality and so I added it using an external library from Mirrajabi called ‘search-dialog’ [3]. I decided to use this library as it provides a search bar with built-in functionality of highlighting the text that’s selected or written down in the ‘Edit Text’ field by the user and also it overlays on the screen which provides a good user experience rather than other search bars which overlap on the text provided on the screen with a ListView. Further working with this dependency was easier than working with others as it seems well designed. The Search Bar was added in the Saved Experiments section which contains a lot of default experiments along with their respective manuals. The search bar was intended to provide the user with a greater UI so that they don’t need to navigate through sections every time to find an experiment. This blog is a step by step guide on how to implement it in any app. First, add dependencies in the gradle at both project level and app level. By adding these dependencies, we don’t need to worry about writing code for how the Search Bar will filter searches and how it will be placed on the screen. App Level : 'com.github.mirrajabi:search-dialog:1.1' Project Level : maven { url "https://jitpack.io" }  Create a SearchModel class which will help to carry out the search operations. public class SearchModel implements Searchable { private String mTitle; public SearchModel(String mTitle) { this.mTitle = mTitle; } public void setTitle(String mTitle) { this.mTitle = mTitle; } @Override public String getTitle() { return mTitle; } } The SearchModel class helps to communicate with the filtered search results by returning the string which is selected: SearchModel(String string) - It is a default constructor setTitle(String string) - It is a method used to set the string provided in the search results getTitle() - It is also a method to get the string selected by the user from the filtered search result provided  Now provide some data which needs to be searched using an ArrayList or by using StringArrays and then converting it to Search Model Object. private ArrayList<SampleSearchModel> createSampleData(){ ArrayList<SampleSearchModel> items = new ArrayList<>(); items.add(new SampleSearchModel("First item")); items.add(new SampleSearchModel("Second item")); items.add(new SampleSearchModel("Third item")); items.add(new SampleSearchModel("Fourth item")); return items; }  At last add the constructor in MainActivity to make the search bar. SimpleSearchDialogCompat(Context context, String title, String searchHint, @Nullable Filter…

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