NXP AN13694 Smart Home Demo on GUI Guider for LPC546XX User Guide
- June 4, 2024
- NXP
Table of Contents
NXP AN13694 Smart Home Demo on GUI Guider for LPC546XX User Guide
Document information
| Information | Content |
|---|---|
| Keywords | AN13694, GUI Guider, LVGL, Smart Home, LPC546xx |
| Abstract | This application note takes smart home as an example to introduce |
the GUI Guider-based development flow, including GUI design and simulation, code generation and debugging, downloading to and running on the evaluation board.
Introduction
The smart home has had a rapid and significant development in recent years. To provide services such as lighting control, telephone remote control, anti theft alarm, and environmental monitoring, the smart home interconnects various household electrical appliances. The smart home also integrates network communication, equipment automation, and information appliances. Therefore, the smart home can allocate resources and play an important role in reducing energy consumption and environmental protection.
Embedded systems with graphical interface, low-power consumption, and high performance play a pivotal role in the smart home field. NXP provides a complete GUI solution called GUI Guider, which utilizes the LVGL graphics library.
This application note takes smart home as an example to introduce the GUI Guiderbased development flow, including:
- GUI design and simulation
- Code generation and debugging
- Downloading to and running on the evaluation board
LVGL
LVGL is an open-source graphics library. It provides everything that you require to create an embedded GUI with easy-to-use graphical elements, beautiful visual effects, and a low memory footprint.
Key features:
- Open source and free to use under MIT license
- Written in C (C++ compatible) and hosted on GitHub
- More than 30 powerful, fully customizable widgets, such as button, image button, checkbox, switch, slider, label, arc, bar, line, canvas, image, roller, slider, meter, table, text area, animation, calendar, chart, list, menu, message box, tabview, and so on
- Display of any resolution, GPU support, multi-display support
- Supports multiple types of input devices:
- Pointer-like input devices such as touchpad or mouse
- Keypads such as a normal keyboard or simple numeric keypad
- Encoders with left/right turn and push options
- External hardware buttons which are assigned to specific points on the screen
- Drawing features:
- Anti-aliasing
- Shadow
- Line, arc, polygon
- Mask
- Text features:
- UTF-8 support
- Kerning
- Word wrap and auto texts scrolling
- rabic and Persian support
- Font compression
- Subpixel rendering
- Online and offline font converter
- Interface for custom font engine
- FreeType integration example
- Multi-language support
- Image features:
- Various color formats: RGB, ARGB, Chroma keyed, indexed, alpha only
- Real-time recoloring of images
- Real-time zoom and rotation
- Images can be stored in flash or files (for example, SD card)
- Online and offline image converter
- Image decoder interface for caching
- PNG integration example
- Styles:
- Cascade styles (like in CSS)
- Reuse the styles in multiple widgets
- Local styles for simple changes
- Themes to give a default appearance
- Transitions (animations) on state change
- Micropython support
- Rich demo examples and documents
For more details, please refer to LVGL
GUI Guider
GUI Guider, a user-friendly graphical user interface development tool from NXP, enables the rapid development of high quality displays with the open- source LVGL graphics library. The drag-and-drop editor of GUI Guider makes it easy to utilize the many features of LVGL. These features include widgets, animations, and styles to create a GUI with minimal or no coding at all.
With the click of a button, you can run your application in a simulated environment or export it to a target project. Generated code from GUI Guider can easily be added to an MCUXpresso IDE or IAR Embedded Workbench project, accelerating the development process and allowing you to add an embedded user interface to your application seamlessly.
GUI Guider is free to use general purpose and crossover MCUs of NXP and includes built-in project templates for several supported platforms.
For more details, please refer to GUI Guider.
GUI Development Flow
In general, the GUI development flow based on GUI Guider is shown in Figure 1.
As shown in Figure 1, after completing the design, it is recommended to perform a simulation to verify whether the simulation results are as expected or not. If the simulation is successful and as expected, the code can be generated. Otherwise, continue to adjust the design.
One suggestion is to divide the design into GUI-related and GUI independent parts. GUIrelated parts include various widgets, such as buttons, images, sliders, animations, etc., as well as human-machine interaction, such as button click events. The GUI-independent part refers to the part related to a specific hardware system, such as hardware timers, onboard sensors, and so on. This ensures that the design can be verified to the greatest extent possible.
Smart home demo introduction
The smart home demo described in this application note is a GUI application with 8 screens. These screens include five main screens and three child- screens attached to the main screens. The relationship between the eight screens is shown in Table 1. The appearances of these screens are shown in Figure 2, Figure 3, and Figure 4.
Table 1. Relationship between main screens and sub screens
Screen ID| Main screen| First level of child screen| Second
level of child screen
---|---|---|---
1| Home| |
2| Temperature| |
3| Light| |
4| Security| Security pin enter| Security pin confirm
Screen ID| Main screen| First level of child screen| Second
level of child screen
---|---|---|---
5| Audio player| Audio list|
Note: The date, time, and weather presented here are not functional since they are dependent on the hardware of the device. The date and time can be controlled by RTC in an embedded system. It is the same for other screens in the GUI demo.
Development environment
This chapter introduces the software and hardware development environment for the smart home demo.
Hardware Environment
Hardware development environment for smart home demo consists of two parts: PC with GUI Guider tool installed and an evaluation board equipped with LPC54628 – LPCXpresso54628 (OM13098).
The LPCXpresso54628 board is a binary backward compatible with the LPCXpresso54608 and LPCXpresso54618 boards. For this reason, this demo is easily ported to LPC54608-based or LPC54618-based hardware platforms with only few modifications.
Software environment
Smart home demo requires GUI Guider with version 1.3.1 to set up the software environment. GUI Guider with version 1.3.1 supports LVGL with versions 7.10.1 and 8.0.2. The demo described in this application note is based on LVGL with version 8.0.2.
Smart home demo implementation
This chapter introduces the key points in the smart home demo implementation process.
reate a new GUI Guider project
To create a GUI Guider project, follow the steps below:
-
To launch the GUI Guider, double-click the GUI Guider icon
-
To start the process of project creation, click the Create a new project button.
-
Select LVGL version as v8 and click the Next button.
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Select LPC54628 as target board template and then click the Next button.
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Select an empty application template, EmptyUI.
-
Perform project settings, such as project name, project location, panel type, and color depth.
-
The created project is shown in Figure 12.
Add GUI widgets and set widgets property
GUI Guider supports adding widgets such as button, image, image button to the workspace by dragging and dropping. To illustrate how to add widgets to the workspace, consider adding an image button as an example.
To add widgets to the workspace, follow the steps below:
-
Type imgbtn in the search box of the Widgets tab, and then drag the image button to the workspace, as shown in Figure 13.
-
Once the image button is placed in the workspace, set the properties of the image button, as shown in Figure 14.
Note: For widgets that require image path, before specifying the image for the widget, add the required image files to the import folder, as shown in Figure 15 and Figure 16.
Human–machine interaction
Different screens show different functions in multi-screen applications. Therefore, it is necessary to provide human-machine interaction to perform screen switching or other functions. Human-machine interaction can be achieved by adding events to the widgets of the GUI.
Consider an example of clicking a button to switch from one screen to another to introduce how to add events to the widget.
The home screen of the smart home demo has a button called Temp. To switch to the TEMPERATURE screen, Temp button on the screen must be clicked, as shown in Figure 17.
To implement this function, it is necessary to add event to the Temp button, as shown in Figure 18.
Simulation
After the design is complete, the simulator can be launched to check whether the simulation results match the expected functionality or not. The launching of the simulator is shown in Figure 19.
The running result of smart home demo in the simulator is shown in Figure 20.
Export Code Project
After the simulation is successfully executed, use the code generation function of GUI Guider to export code based on Keil, IAR, and MCUXpresso IDEs for smart home demo.
As shown in Figure 21, click Run > Target Keil to export the code. Certainly, it is also possible to export IAR-based or MCUXpresso-based projects.
External SPI Flash Support
After the code of smart home demo is exported, compile it. Figure 22 shows compilation errors in the compilation output window.
When GUI Guider with version 1.3.1 exports code, the Code section and the RO
section of the application, that is, the picture data, are stored in the on-
chip flash by default.
All image data cannot be stored in the on-chip flash since LPC54628 only has
512 kB on-chip flash, whereas all picture data is around 800 kB. As a result,
several no-space compilation errors are generated when the code is compiled.
The LPCXpresso54628 evaluation board has an onboard SPI flash, therefore we can map the picture data to the SPI flash.
To support the SPI flash, perform the following steps:
-
Set the pin multiplexing function for pins connected to the SPI flash. The corresponding code is located in pin_mux.c.
-
Add SPIFI driver including fsl_spifi.c and fsl_spifi.h to the code project.
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Add the SPI flash driver to the code.
-
The main function in lvgl_guider.c calls the SPI flash initialization function, which is called spifi_flash_init, as shown in Figure 25.
-
Modify the scatter file. Provide the address space for SPI flash and map the picture files to the address space corresponding to the SPI flash. The scatter file is LPC54628J512_flash.scf and the storage path is deploy\Keil\sdk \LPC54628\arm
These files are objective files compiled from the C files for pictures located in deploy\Keil \sdk\generated\images, as shown in Figure 29.
Set Flash Programming Algorithm
Since SPI flash is used to store pictures, the programming algorithm of SPI flash must be added to Keil IDE. Thus after the download process starts, the SPI flash can be erased and the picture data can be downloaded to the SPI flash. Figure 30 shows the method of adding flash programming algorithm to Keil.
Storage Optimization
To improve the efficiency of memory use, it is necessary to take measures to optimize the use of memory. The commonly used optimization measures are described as follows:
-
Set IDE optimization level for Keil IDE as shown in Figure 31.
-
Compile the code with the release version. Figure 32 shows the selection of compiled version in Keil IDE.
-
Crop the LVGL configuration file called lv_conf.h and do not compile the code of the widget that is not used. For example, smart home does not use the Spinner widget.
Configure the macro, LV_USE_SPINNER, to 0, as shown in Figure 33.
Demonstration
This section includes steps for demonstration purpose as follows:
- Download the code project attached to this application note.
- Compile the code project and download the executable binary file to LPC54628 EVK board.
- To start up the application, re-power or reset the EVK board.
Revision history
Table 2. Revision history
| Rev. | Date | Description |
|---|---|---|
| 0 | 20 July 2022 | Initial release |
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Date of release: 20 July 2022
Document identifier: AN13694