Building libdaq example applications / libraries¶

https://support.criticallink.com/gitweb/?p=libdaq.git;a=tree;h=refs/heads/master;hb=refs/heads/master

The libdaq folder contains a bunch of different libraries for controlling different devices from userspace. Some of these have a "main()" to allow testing the library, and we can build them using the following

source /opt/criticallink/mitysom-335x_2020-08-20/environment-setup-cortexa8t2hf-neon-criticallink-linux-gnueabi
git clone https://git.criticallink.com/git/libdaq.git
cd libdaq
./autogen.sh
./configure --host=arm-criticallink-linux-gnueabi --enable-factoryconfig=no
make -j$(nproc)

The most useful example binaries are likely going to be "gpio", "gpiosingle" and "pwm"

 $ ls -l gpio pwm
-rwxr-xr-x 1 jcormier engineer 119868 Mar 24 10:28 gpio
-rwxr-xr-x 1 jcormier engineer 119868 Mar 24 10:28 gpiosingle
-rwxr-xr-x 1 jcormier engineer  51164 Mar 24 10:28 pwm

Building and using gpiosingle with QT and QtCreator¶

• Create a test project for this demo. File -> New File or Project
  • Application -> Qt Widgets Application
  • Name: TestMe
  • Accept defaults. Make sure to pick a valid Kit
• Checkout libdaq inside project folder
  

  Documents/TestMe$ git clone https://git.criticallink.com/git/libdaq.git
  Cloning into 'libdaq'...
  remote: Counting objects: 969, done.
  remote: Compressing objects: 100% (346/346), done.
  remote: Total 969 (delta 689), reused 872 (delta 616)
  Receiving objects: 100% (969/969), 549.12 KiB | 8.32 MiB/s, done.
  Resolving deltas: 100% (689/689), done.
  

• Open project in QtCreator
• Right-click in the project area and click "Add existing files". Then select "gpiosingle.cpp" and "gpiosingle.h"

• Build the project
  Note: If you get various #include file not found warnings, make sure you are compiling for Linux or with the arm cross-compile toolchain. The libdaq libraries are not designed to build for Windows.
• Open mainwindow.h
  • Add @#include "libdaq/gpiosingle.h"
  • Under private and the mainwindow ui, add
    

        Ui::MainWindow *ui;
    
        MityDSP::tcGpioSingle redLed;
    

• Open mainwindow.cpp
• Above the class, add:
  

  #define GPIO_TO_PIN(bank, gpio) ((bank)*32 + (gpio))
  

  
  Note: This changes depending on the processor, the above is correct for the AM335x. The L138 however would be 16 instead of 32...
  • In the constructor, initialize the gpio to the correct gpio number, and ensure the direction is set
    Note: gpio1_12 was picked at random, the devkit doesn't have any gpios attached to LEDs. This is just an example
    

    MainWindow::MainWindow(QWidget *parent)
        : QMainWindow(parent)
        , ui(new Ui::MainWindow)
        , gpioRedLed(GPIO_TO_NUM(1,12)) // gpio1_12
    {
        ui->setupUi(this);
    
        gpioRedLed.setDirection(1, 0); // Set gpio as output low
    }
    

• Add a ToggleLED button to the mainwindow form and create a clicked handler

• Setup click handler to get current gpio value and flip it so we toggle the LED on then off each time the button is pushed
  

  void MainWindow::on_pbToggleLed_clicked()
  {
      int ret;
      unsigned int value;
  
      ret = gpioRedLed.GetValue(value);
      if (ret < 0) {
          qDebug() << "Error: Failed to get gpio value";
          return;
      }
      ret = gpioRedLed.SetValue(!value);
      if (ret < 0) {
          qDebug() << "Error: Failed to set gpio value";
          return;
      }
  }
  

Attached modified mainwindow files: mainwindow.h mainwindow.ui mainwindow.cpp