# Build and run the application

## In this learning path

- [Introduction](https://learn.arm.com/learning-paths/embedded-and-microcontrollers/cmsis_rtx/)
- [Create and setup Keil MDK project](https://learn.arm.com/learning-paths/embedded-and-microcontrollers/cmsis_rtx/create/)
- [Initialize the operating system](https://learn.arm.com/learning-paths/embedded-and-microcontrollers/cmsis_rtx/initialize/)
- [Create RTOS threads](https://learn.arm.com/learning-paths/embedded-and-microcontrollers/cmsis_rtx/threads/)
- [Build and run the application](https://learn.arm.com/learning-paths/embedded-and-microcontrollers/cmsis_rtx/build_and_run/)
- [Using Event Recorder](https://learn.arm.com/learning-paths/embedded-and-microcontrollers/cmsis_rtx/eventrecorder/)
- [Next Steps](https://learn.arm.com/learning-paths/embedded-and-microcontrollers/cmsis_rtx/_next-steps/)

You are now ready to build and run the application. The method and capabilities of [Keil MDK](https://learn.arm.com/learning-paths/embedded-and-microcontrollers/cmsis_rtx/build_and_run/#mdk) and [Arm Development Studio](https://learn.arm.com/learning-paths/embedded-and-microcontrollers/cmsis_rtx/build_and_run/#armds) are quite different. Refer to the appropriate section below.

## Build and run the example (Keil MDK)

Save all files, and click `build` (`F7`) the example. Click `Debug` (`Ctrl+F5`) to launch the FVP, and put the IDE into debug mode.

- Use the menu (`View` > `Watch Windows` > `RTX RTOS`) to observe the RTOS features.
- Use the menu (`View` > `Serial Windows` > `Debug (printf)`) to observe the printf output.

Click `Run` (`F5`) to start the application, and after a short time, click `Stop`. Observe in the `RTX RTOS` view that the threads have been created. Two other threads, `osRtxIdleThread` and `osRtxTimerThread` will also be created.

![RTX RTOS threads view](https://learn.arm.com/learning-paths/embedded-and-microcontrollers/cmsis_rtx/keil_rtos.png)  
*RTX RTOS threads view*

However, no output is seen in the `printf viewer`. This is because semihosting isn’t supported. You’ll learn how to address this in the next section.

Exit the debug session (`Ctrl+F5`).

## Build and run the example (Arm Development Studio)

Save all files, then right-click on the project, and select `Build Project`. A `.axf` file will be generated in the `Configuration Name` folder. You must now create a `Debug Configuration`:

- Navigate the menu to `File` > `New` > `Model Connection`.
- Create a Debug connection, and associate it with your project.
- Select the `MPS2_Cortex-M4` from the selection of FVPs Installed with Arm DS.
- In the Debug configuration view:
  - In `Files` tab, browse for your `.axf` image.
  - In `Debugger` tab, select `Debug from symbol (main)`.
  - In `OS Awareness` tab, select `Keil CMSIS-RTOS RTX` from the pull-down.
  - Click `Apply` to save all settings, then click `Debug`.
    - Subsequent debug sessions can be invoked directly from the `Debug Control` pane.

When debugging, use the `OS Data` view to observe RTOS information. Open from the `Window` > `Show View` menu. Use the pull down to select different categories.

![OS Data view with thread details](https://learn.arm.com/learning-paths/embedded-and-microcontrollers/cmsis_rtx/os_data.png)  
*OS Data view with thread details*

For thread aware debug, right-click on the debug connection in the `Debug Control` view, and select `Display threads`.

![Debug Control view with thread display option](https://learn.arm.com/learning-paths/embedded-and-microcontrollers/cmsis_rtx/debug_control.png)  
*Debug Control view with thread display option*

You’ll see the `printf()` output in the `Target Console` pane.

```
hello from thread 1
hello from thread 2
hello from thread 3
hello from thread 1
hello from thread 2
...
```