# Understanding TotalCross for Linux ARM ## Introduction See at this guide: * Discover plugin for VS Code; * Getting your Hello World App cooler; * How to deploy; * After basics; ## Requirements Complete the Getting Started: {% content-ref url="/pages/-M2j3gfmD-ARGTuW\_2DN" %} [Getting Started](/master/documentation/get-started.md) {% endcontent-ref %} The following electronic components are also required: * Raspberry Pi 3; * 7x jumpers male-female; * Protoboard; * LED RGB module (or common 4 pins LED RGB); * Push-button module (or common push-button). In order to execute Gpiod methods at your embedded device, you will also need to have the libgpiod-dev package installed in your board. You can do that by entering the following command at the device's terminal: ```java $ sudo apt-get install libgpiod-dev ``` ## **Guide** ### Discover VS Code plugin A quick way to start using TotalCross is installing the [TotalCross extension for VS Code](https://marketplace.visualstudio.com/items?itemName=Italo.totalcross). **Step 1:** open VS Code console (CTRL + Shift + P) and type TotalC… autocomplete should help! ![](/files/-Lun83v5b4ERDVyE7VT-) **Step 2:** select *TotalCross: Create new Project;* **Step 3:** create a folder called *HelloWorld* and select it; **Step 4:** *GroupId* will be `com.totalcross`; **Step 5:** *ArtifactId* will be `HelloWorld`*;* **Step 6:** select the latest version of TotalCross SDK and `-linux-arm` platform; ![Click to expand](/files/-Lun8cZb1egyD-mqZBhj) **Step 7:** open`RunHelloWorldApplication.java` and click *Run* (IDE). The result should be: ![Click to expand](/files/-Lun9-JBKRLqV_24--Q4) **Step 8:** watch the integrated simulator! ### Getting your Hello World App even more Cooler :cold\_face: :sweat\_smile: The following project deals with the control of an RGB LED with user interface buttons and a pin reset button! ![](/files/-LzgpT8LCC3-7z58c_wO) **Step 1:** follow the schematic: ![](/files/-Lzcj5bEWsjwrkCoCK58) **Step 2:** to work with pin logic after `public class HelloWorld extends MainWindow {` add: ```java // Integers to store pin numbers private int R = 4, G = 17, B = 27, pushButton = 18; // Integers to store state of each LED pin, 0 (LOW) and 1 (HIGH) private int sttR, sttG, sttB; // Buttons to control colors private Button btnR, btnG, btnB; ``` {% hint style="danger" %} If you need to work with different pinouts check the manufacturer manual! {% endhint %} **Step 3:** at *HelloWorld.java* in `initUI()` code add: ```java // Label helloWorld made on project creation Label helloWorld = new Label("Hello World!"); // Change the position of label on the Y axis, with TOP (beginning of Y) + a fill of 20 add(helloWorld, CENTER, TOP + 20); ``` **Step 4:** then, board setup: ```java // Board Setup GpiodChip gpioChip = GpiodChip.open(0); GpiodLine pinR = gpioChip.line(R); GpiodLine pinG = gpioChip.line(G); GpiodLine pinB = gpioChip.line(B); GpiodLine pinPushButton = gpioChip.line(pushButton); ``` **Step 5:** pins setup: ```java // Set LED pins as outputs and default value sttX pinR.requestOutput("CONSUMER",sttR); pinG.requestOutput("CONSUMER",sttG); pinB.requestOutput("CONSUMER",sttB); // Set Reset pin as input pinPushButton.requestInput("CONSUMER"); ``` **Step 6:** the red button: ```java // The TotalCross button: btnR = new Button("R"); // Button instantiation // without text btnR.setBackColor(Color.RED); // Set background color (red) btnR.addPressListener(new PressListener() { // Press event listener @Override public void controlPressed(ControlEvent controlEvent) { sttR = 1 - sttR; // Invert pin state pinR.setValue(sttR); // Set value (HIGH or LOW) } }); add(btnR, CENTER - 70, AFTER + 40); // To make horizontally aligned // buttons in the 'RGB' sequence, // take the center reference and // decrease 70 to place the // leftmost R. In the Y axis just // take the reference of the // previous component and add 40 ``` **Step 7:** and the other buttons: ```java btnG = new Button("G"); btnG.setBackColor(Color.GREEN); btnG.addPressListener(new PressListener() { @Override public void controlPressed(ControlEvent controlEvent) { sttG = 1 - sttG; // Pay attention to change pin!!! pinG.setValue(sttG); } }); add(btnG, CENTER, SAME); // The green button will be // placed at the center and in // the same line of previous // button btnB = new Button("B"); btnB.setBackColor(Color.BLUE); btnB.addPressListener(new PressListener() { @Override public void controlPressed(ControlEvent controlEvent) { sttB = 1 - sttB; // Pay attention to change pin!!! pinB.setValue(sttB); } }); add(btnB, CENTER + 70, SAME); // The last button will be placed // to the right of the center. ``` **Step 8:** finally we use a thread to check the state of the reset button: ```java // A thread will be used to check every 20 ms, if the reset button has been pressed: if yes then // the pin state goes to LOW new Thread() { @Override public void run() { while(true){ if(pinPushButton.getValue() == 1) { sttG = 1 - sttG; sttR = 1 - sttR; sttB = 1 - sttB; pinR.setValue(sttR); pinG.setValue(sttG); pinB.setValue(sttB); } Vm.sleep(100); } } }.start(); ``` **Step 9:** run *RunHelloWorldApplication.java* again and watch the results! ![](/files/-LunDOEt3v1aVNDLqxjG) {% hint style="info" %} View fully code [here](https://gist.github.com/acmlira/e6c18f0a82688f750c1648af4d101344) {% endhint %} ### How to deploy **Step 1:** open VS Code console (CTRL + Shift + P) and select *TotalCross: Deploy* ![](/files/-LunDi6Z-vuOMZiz2XLo) **Step 2:** a second dialog box will appear and just fill in the board's information: ![](/files/-LunDoXYlF_oU9Y39NP7) **Step 3:** see the results in screen or VNC ![](/files/-LunDsKM3Yzmhnvpb_Ub) ### After basics This was the beginning of application development for TotalCross embedded systems, how about taking a look at [TCSample](https://github.com/TotalCross/TCSample) and seeing all that can be done? See dashboard made especially for Web Summit 2019: ![](/files/-LunFODqxapPPckKLGiW) ## See more Are you interested in development with embedded systems? Contact us via [Telegram](https://t.me/comunidadetotalcross)! ![Bruno Muniz, Lucas Galvanini e Pedro Lyra no WebSummit](/files/-LunDx-hDEZniSPFP55o) ## References * [Fritzing ](https://fritzing.org/home/) --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://learn.totalcross.com/master/documentation/guides/understanding-totalcross-for-linux-arm.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. 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