ePaper, as an advanced display technology, boasts numerous advantages such as lower power consumption, excellent eye-protection features, and higher reading comfort. However, it also comes with certain pain points that might impact user experience. For example:

1.Slow refresh rates and response times:

E-ink displays typically have slower refresh rates compared to LCD screens, resulting in potential delays and less smooth transitions during scrolling or page switching.

2.Unsuitability for videos and dynamic content:

E-ink screens are suitable for static content and text display but lack robust support for videos, animations, or other high-refresh-rate content.

3.Monochrome display:

Most e-ink screens only support black and white or grayscale, limiting their ability to display color content, which may restrict certain applications and needs.

4.Susceptibility to ambient light:

E-ink screens perform well in low or dim lighting conditions but might face issues such as reflection and readability difficulties when exposed to strong light.

5.Limited storage space:

The small memory capacity of e-ink devices poses challenges for users during usage.

Solution Overview for Insufficient Memory:

During the usage of electronic paper, users may encounter storage space limitations due to constrained memory capacity, necessitating frequent memory clean-ups or deletion of essential files. This issue can particularly pose a challenge in applications involving microcontroller units where insufficient memory becomes a concern. However, to address this problem, the innovative and effective use of SD cards presents a promising avenue for advancing electronic paper technology.

Hardware aspect:

Connecting an SD card to a microcontroller involves ensuring the correct connection of the SD card slot and providing the appropriate voltage supply (usually 3.3V).

Pin descriptions: 

   1) SI (INT): SPI master input/slave output data pin;

   2) SO: SPI master output/slave input data pin;

   3) SCK: SPI clock signal pin;

   4) CS1: SD card chip select pin.

Software aspect:

Initialize SD card:

Use microcontroller programming to initialize the SD card via the relevant interface, including configuring the communication protocol (such as SPI or SDIO) and sending commands to start the SD card.

Implement file system:

Create a file system (such as FAT32, exFAT) on the SD card, which can be managed using corresponding libraries or operating systems to facilitate reading and writing files on the SD card.

Steps to follow:

1.Connect hardware:

   1) Properly connect the SD card to the microcontroller.

   2) Provide a stable voltage (typically 3.3V).

   3) Check and describe the functions of each pin connected to the SD card.

2.Software Initialization:

   1) Initialize the SD card in the microcontroller program.

   2) Configure communication protocols and send the boot command.

3.Create a file system:

   1) Establish a file system, such as FAT32 or exFAT, on an SD card.

   2) Utilize suitable libraries or operating systems to manage the file system, facilitating file read and write operations.

4.Steps to parse and display BMP format images on an E Ink display:

   1) Image Format Selection:

Saving images in BMP format in monochrome (black and white) when using monochrome electronic paper.

   2) SD Card Storage:

Save the required monochrome BMP format images onto the SD card connected to the microcontroller.

   3) Image Analysis:

     A.Open the image file:

    File imageFile = SD.open("/1.bmp");

     B.Reading image header information:

    Parsing the BMP file header, including file type, size, width, height, bit depth, and other details. The BMP file header         typically comprises the file type identifier, file size, offset address of the pixel array, and more.

     C.Reading Pixel Data:

    Pixel data in BMP files is stored in the data section, and it is read based on the information in the file header. In monochrome BMP files, each pixel is typically represented using one bit (1-bit), with each bit corresponding to either black or white.

     D.Interpret and Convert Pixel Data:

        Interpret pixel data to map monochrome pixels onto an e-paper display format. For instance, convert black pixels from a BMP file to black dots on an e-paper display, and white pixels to white dots.

   4) Image Display:

     A.ePaper Display Configuration:

Utilize a microcontroller for controlling the e-paper display. Configure the e-paper display area to match the size of the BMP image.

     B.Writing Parsed Pixel Data to E-paper:

Using the microcontroller, write the parsed pixel data onto the ePaper display. Considering the characteristics of the e-paper, write pixel data line-by-line or in blocks to display the complete image.

     C.Refresh Display:

Upon completion of writing pixel data, refresh the ePaper to display the image. 

   5) Notes:

Ensure accurate parsing of BMP file header information and pixel data to guarantee proper display. Due to the use of one bit per pixel in monochrome BMP images, special attention is required during the parsing and mapping process to avoid data loss or incorrect conversion.

5.Key Points to Note

SD Card Operation:

The recognition and data transmission process of an SD card involves the host (SDIO controller) sending commands, to which the SD card responds by providing the necessary data requested by the host.

* If you're interested, you can check the link below:

1.54-inch tri-color E Ink screen module with built-in Flash chip and frontlight/touchscreen drive board, DESPI-K154Z90_Good Display (good-display.com)

The module is equipped with a Flash chip, specifically the W25Q128 model. W25Q128 is a 128M-bit (16M-byte) serial NOR Flash memory, which conveniently allows users to store images, fonts, and related data. Additionally, the module includes a reserved slot for an SD card, enabling users to opt for a Micro SD card as needed. The presence of the Flash chip and SD card slot addresses users' concerns regarding storage space.

Closing Statement

As a solution to the limited memory capacity in e-paper devices, the SD card presents an effective avenue in both hardware and software realms. Through appropriate connections and program control, the SD card effectively expands storage space, offering new possibilities for the advancement of e-paper technology. Our team boasts extensive expertise in image processing and parsing, ensuring accurate interpretation of BMP file header information and pixel data, thereby guaranteeing flawless data conversion for optimal display results. Our experience spans various image formats' parsing, enabling the development of product prototypes based on this technological solution. Feel free to explore our developers' GitHub page for more related projects and code samples.

Click here: https://github.com/bitbank2