The ease of use and speed of adaptation are more important to modern users than knowing how a technology operates internally. The consumer electronics industry is concentrating on integrating beautiful displays and touchscreen interfaces due to the demand for IoT-based appliances. Products such as refrigerators, washing machines, micro-ovens, smartwatches, VR technologies, home automation systems, and even car entertainment systems are included in this trend. 

In the realm of consumer electronics, a product’s success is largely determined by its user interface (UI). Designing goods connected to displays requires careful consideration of both hardware and software/firmware factors. Selecting the right hardware, such as display components like AMOLED, TFT, and e-Ink, along with the right software/firmware and UI framework, can greatly improve the user experience.  

Unique challenges include resource constraints, hardware integration, task-oriented focus, context awareness, usability in demanding environments, physical constraints, feedback mechanisms, customization options, power consumption, maintenance considerations, and regulatory compliance when designing user experience and interfaces for embedded systems. To provide a flawless user experience, the procedure includes maximizing efficiency, adjusting to the surroundings, and prioritizing crucial functions. 

Why does user experience matter in embedded systems? 

In embedded systems, user experience (UX) is crucial to guaranteeing usability, security, and dependability, especially in critical applications such as healthcare. Product adoption, error reduction, and user pleasure are all increased by a well-designed user experience. In addition, it guarantees regulatory standard compliance, reduces support and development expenses, and distinguishes items in the market. Effective user experience (UX) is a critical component of embedded systems success since it ultimately results in more successful and user-friendly products. 

• Usability: A well-thought-out interface minimizes errors and facilitates system use. For technology utilized in vital operations like self-driving automobiles, this is essential. 

• Accessibility: Ensuring that all users can effectively interact with the system is ensured by designing for a range of user needs and abilities. 

• Efficiency: For users who often engage with the system, a seamless user experience shortens training times and boosts productivity. 

An embedded device’s architecture is the basic structure that governs its operation, considering things like hardware, security, and intended use. The CPU, RAM, peripheral devices, I/O interfaces, power supply, operating system (or real-time operating system), security features, communication protocols, and application software are examples of important parts. These components’ choices are made with the device’s specific requirements in mind, striking a balance between cost, power consumption, performance, and usefulness. 

Design considerations:

Hardware

• Embedded displays provide user interaction and information about device operation. 

• Several display options exist, including TFT, LCD, OLED, AMOLED, and e-Ink, each with its own advantages and drawbacks. 

Key Display Selection Parameters:

• Number of Pixels (resolution): Determines image sharpness. 

• Color Depth: Defines the number of colors displayable (e.g., RGB565 format). 

Calculating Frame Buffer Size:

• The frame buffer stores image data for display. 

• Its size depends on resolution and color depth: 

Frame Buffer Size (bytes) = Number of Pixels * Color Depth / 8

Example: 

• Using a 320×480 pixel display with RGB565 format (16-bit color depth): 

Frame Buffer Size = 320 x 480 x 16 / 8 = 307,200 bytes (approximately 307 KB)

Selecting Frame Buffer Memory:

• The frame buffer resides in RAM before being sent to the display. 

• Developers can choose internal MCU RAM or external PSRAM (Pseudo-Static RAM). 

Internal RAM:

• Pros: Faster access, smoother rendering. 

• Cons: Limited space competes with other system components. 

• Suitable for: Devices with sufficient internal RAM and less demanding displays. 

External PSRAM:

• Pros: Larger capacity. 

• Cons: Slower access than internal RAM. 

• Suitable for: Devices requiring more memory or facing internal RAM limitations. 

• Tip: Use DMA (Direct Memory Access) for faster PSRAM access with the display. 

Number of Framebuffers for Smooth Performance:

• A higher number of frame buffers can increase Frame Per Second (FPS) rate, leading to a smoother user experience. 

Factors Affecting FPS:

• Number of Framebuffers: More buffers allow double buffering for smoother transitions. 

• Display Refresh Rate: Higher refresh rates (e.g., MIPI > QSPI > SPI) update the display faster. 

• Inbuilt Graphics Engine: Offloads rendering from the main processor, improving FPS. 

Software/Firmware:

It takes knowledge of both user experience (UX) and user interface (UI) design principles, as well as a firm grasp of the development platforms and libraries made especially for embedded systems, to create an aesthetically beautiful user interface (UI) for embedded systems. Certain limitations, like constrained memory, processing power, and display capabilities, are common to embedded devices. The following are some noteworthy choices for UI frameworks in the field of embedded systems: 

Selecting the right UI framework/libraries becomes essential in this situation. Below is a condensed feature comparison of the embedded system UI frameworks mentioned:

Developers should consider various aspects, including the target application’s unique features, ease of integration, community support, and resource needs, while selecting a UI framework for embedded devices. A good implementation also requires interoperability with the selected hardware and software stack. 

User-centric design is a critical process in embedded systems development. First, dissecting tasks, locating interaction points, and comprehending information flow—which is graphically depicted by flowcharts—are all necessary for creating user flows and interaction models. By giving priority to the most important information, utilizing plain language, accounting for the limited input methods available, and utilizing visual cues, user interface (UI) design tackles system restrictions.  

Efficient access to relevant data is ensured by prioritizing information according to user demands and context. During the testing and validation phase, a broad user group is used for usability testing, precise goals are established, and user behavior is observed. Continuous improvement is ensured by iterating on the design, concentrating on important problems, making wise adjustments, and repeating testing. The ultimate objective is to guarantee that the user interface (UI) facilitates smooth interaction within the embedded system by being clear, intuitive, and in line with user expectations. A user-friendly, effective, and well-adapted embedded system interface is guaranteed by this all-encompassing approach. 

Bottomline

When designing user interfaces (UI) for embedded systems, such as wearables and smart appliances, user needs must be prioritized over hardware and software constraints. The need for these devices is growing, which emphasizes how crucial it is to design user interfaces (UIs) that are simple to use and effective to boost customer happiness and product success. The concepts of user-centered design are critical; designers must concentrate on important details, unambiguous interactions, and resolving system constraints. Testing the usability of the UI with a variety of users guarantees that it is efficient, intuitive, and meets user expectations. For more information on integrating these principles with STM32 hardware, you can refer to this guide for developing USB composite device for STM32 hardware platform.

In the end, a good embedded system provides a user-friendly interface, smoothly combines hardware and software, and efficiently responds to user requests. Improving user experiences will continue to be crucial in determining how consumer devices develop in the future as technology develops.