Understanding TotalCross for Linux ARM
See at this guide:
Discover plugin for VS Code;
Getting your Hello World App cooler;
How to deploy;
After basics;
Complete the Getting Started:
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:
$ sudo apt-get install libgpiod-dev
A quick way to start using TotalCross is installing the TotalCross extension for VS Code.
Step 1: open VS Code console (CTRL + Shift + P) and type TotalC… autocomplete should help!
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;
Step 7: openRunHelloWorldApplication.java and click Run (IDE). The result should be:
Step 8: watch the integrated simulator!
The following project deals with the control of an RGB LED with user interface buttons and a pin reset button!
Step 1: follow the schematic:
Step 2: to work with pin logic after public class HelloWorld extends MainWindow { add:
// Integers to store pin numbersprivate 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 colorsprivate Button btnR, btnG, btnB;
If you need to work with different pinouts check the manufacturer manual!
Step 3: at HelloWorld.java in initUI() code add:
// Label helloWorld made on project creationLabel helloWorld = new Label("Hello World!");// Change the position of label on the Y axis, with TOP (beginning of Y) + a fill of 20add(helloWorld, CENTER, TOP + 20);
Step 4: then, board setup:
// Board SetupGpiodChip 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:
// Set LED pins as outputs and default value sttXpinR.requestOutput("CONSUMER",sttR);pinG.requestOutput("CONSUMER",sttG);pinB.requestOutput("CONSUMER",sttB);// Set Reset pin as inputpinPushButton.requestInput("CONSUMER");
Step 6: the red button:
// The TotalCross button:btnR = new Button("R"); // Button instantiation// without textbtnR.setBackColor(Color.RED); // Set background color (red)btnR.addPressListener(new PressListener() { // Press event listener@Overridepublic void controlPressed(ControlEvent controlEvent) {sttR = 1 - sttR; // Invert pin statepinR.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:
btnG = new Button("G");btnG.setBackColor(Color.GREEN);btnG.addPressListener(new PressListener() {@Overridepublic 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() {@Overridepublic 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:
// 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 LOWnew Thread() {@Overridepublic 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!
View fully code here
Step 1: open VS Code console (CTRL + Shift + P) and select TotalCross: Deploy
Step 2: a second dialog box will appear and just fill in the board's information:
Step 3: see the results in screen or VNC
This was the beginning of application development for TotalCross embedded systems, how about taking a look at TCSample and seeing all that can be done? See dashboard made especially for Web Summit 2019:
Are you interested in development with embedded systems? Contact us via Telegram!
​Fritzing ​
