Good Display Split-Screen GUI Technology

Categories:Innovation
Author:Yubao Liu
Origin:Original
Time of issue:2025-09-25 16:13
Views:

(Summary description)

Good Display Split-Screen GUI Technology

(Summary description)

Categories:Innovation
Author:Yubao Liu
Origin:Original
Time of issue:2025-09-25 16:13
Views:

Information

Innovative Solution for Driving Large Screens with Limited Memory

Good Display Technical Documentation - Optimized Display Version

1. Understanding GUI Technology

A GUI (Graphical User Interface) essentially functions as a customizable digital canvas that supports drawing basic graphical elements such as points, lines, rectangles, and circles. These elements can be combined to generate text, icons, simple images, and other visual content. The final canvas data is then output to display devices like e-paper or TFT screens.

While early GUI technology was primarily applied to TFT screens, the growing popularity of e-paper in applications such as smart price tags, e-readers, and industrial dashboards has prompted JiaXian Electronics to develop a specialized e-paper GUI solution. This solution eliminates the need for developers to create display logic from scratch. By utilizing the GUI's drawing interfaces, developers can quickly implement customized display requirements—such as updating prices on tags or visualizing data on dashboards—significantly reducing project development cycles.

It's important to note that traditional GUIs require device RAM to store the complete canvas data. The memory footprint is directly proportional to the e-paper's resolution and color depth. The specific calculation formulas are as follows:

1) Monochrome E-paper GUI: RAM Space = (Width × Height) / 8 (bytes)

2) Three-color / Four-color E-paper GUI: RAM Space = (Width × Height) / 4 (bytes)

3) Six-color E-paper GUI: RAM Space = (Width × Height) / 2 (bytes)

When a device has limited RAM capacity (for instance, some cost-effective MCUs have only a few KB of RAM) and cannot accommodate the full canvas data, traditional GUI solutions become impractical. To address this challenge, JiaXian has developed and refined GUI split-screen display technology.

2. GUI Split-Screen Implementation Methodology

The core principle of split-screen GUI is "divide and conquer": instead of storing the entire canvas at once, it is divided into N independent smaller sub-screen canvases. The number of splits (N) depends on both the screen size and the available device RAM—for example, a 2.9-inch e-paper might require only 2 splits, while larger displays might need more. The key is to ensure that each sub-screen's buffer fits within the device's RAM constraints. The display is completed through "batch transmission + unified update" processes.

Using the common 2-split screen approach (suitable for small to medium-sized e-paper displays, such as 5.83 inches) as an example, the implementation process is as follows:

Initial Configuration: The GUI first establishes split-screen parameters (e.g., splitting along the screen's vertical centerline, where both upper and lower halves have a resolution of "Width × Height/2") and allocates the RAM buffer required for a single sub-screen.

Upper Half Processing: The GUI drawing interface is called to render content for the upper half (such as text and icons) in the sub-screen buffer. Once complete, the buffer data is written to the corresponding storage area of the e-paper controller IC.

Lower Half Processing: The sub-screen buffer is cleared, and the drawing operation is repeated for the lower half content. This data is then written to another storage area of the e-paper controller IC.

Full Screen Update: After all sub-screen data has been transferred to the e-paper controller IC, a "Display Update" command is issued. The controller then refreshes the entire screen, ensuring seamless display without visible seams or timing discrepancies.

Through this methodology, even devices with RAM sufficient for only 1/4 or 1/8 of the full canvas can still support GUI functionality. The split-screen operation has no discernible impact on the final display quality.

GUI Split-Screen Data 1

GUI Split-Screen Data 2

...

GUI Split-Screen Data N

Split-Screen Data Combination Schematic

Implementation Code Example

// Data initialization settings

Paint_NewImage(ImageBW, EPD_WIDTH, EPD_HEIGHT/2, 0, WHITE); // Set screen size and display orientation

Paint_selectImage(ImageBW); // Set virtual canvas data storage location

/********** Built-in font chip demonstration **********/

EPD_HW_Init_GUI(); // EPD init GUI

Paint_clear(WHITE);

// Draw text using different font sizes

Paint_DrawString_EN(0, 0, "Good Display", &Font8, WHITE, BLACK); // 5x8 font

Paint_DrawString_EN(0, 10, "Good Display", &Font12, WHITE, BLACK); // 7x12 font

Paint_DrawString_EN(0, 25, "Good Display", &Font16, WHITE, BLACK); // 11x16 font

Paint_DrawString_EN(0, 45, "Good Display", &Font20, WHITE, BLACK); // 14x20 font

Paint_DrawString_EN(0, 80, "Good Display", &Font24, WHITE, BLACK); // 17x24 font

EPD_HW_Init_GUI(); // EPD init GUI

EPD_DisplayHalf1(ImageBW); // Display image 1/2

// Process second half of screen

Paint_Clear(WHITE);

// Draw content for second half

Paint_DrawString_EN(0, 0, "Good Display", &Font8, WHITE, BLACK);

Paint_DrawString_EN(0, 10, "Good Display", &Font12, WHITE, BLACK);

Paint_DrawString_EN(0, 25, "Good Display", &Font16, WHITE, BLACK);

Paint_DrawString_EN(0, 45, "Good Display", &Font20, WHITE, BLACK);

Paint_DrawString_EN(0, 80, "Good Display", &Font24, WHITE, BLACK);

EPD_DisplayHalf2(ImageBW); // Display image 2/2

EPD_Deepsleep(); // EPD deep sleep - this instruction is necessary, please do not delete!

delay_s(2); // 2 second delay

3. Impact on Customer Projects

In e-paper device development, the chip's RAM capacity is a critical factor influencing hardware costs. Within the same chip series, models with smaller RAM capacities (e.g., decreasing from 32KB to 8KB) can reduce procurement costs by 10%-30%. Additionally, chips with smaller RAM typically consume less power, which aligns well with the battery life requirements of portable e-paper devices.

By leveraging GUI split-screen technology, customers no longer need to select high-RAM, high-cost chips to accommodate traditional GUI requirements. Instead, they can directly utilize low-cost chips with limited RAM (such as STM32L0 series MCUs). This approach maintains full display functionality while significantly reducing device hardware costs. Furthermore, the split-screen solution is compatible with JiaXian's existing e-paper modules, eliminating the need for additional hardware changes and minimizing project modification expenses.

From a market perspective, these cost reductions provide customers in competitive segments like smart price tags and portable e-notepads with greater pricing flexibility. Alternatively, they can enhance product specifications at the same price point, thereby strengthening their market competitiveness.

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