CN116935799A

CN116935799A - Method for simulating EPD screen interface by RGB interface

Info

Publication number: CN116935799A
Application number: CN202210321996.0A
Authority: CN
Inventors: 姜从龙
Original assignee: Beijing Ingenic Semiconductor Co Ltd
Current assignee: Beijing Ingenic Semiconductor Co Ltd
Priority date: 2022-03-29
Filing date: 2022-03-29
Publication date: 2023-10-24

Abstract

The application provides a method for simulating an EPD screen interface by an RGB interface, which connects 17-21 data lines in the RGB interface to corresponding control lines of the EPD as simulation output, and then correspondingly sets and adjusts the driving of software. When the software drives the RGB interface to light the LCD, the used linux kernel frame is used for driving the frame buffer, the data to be displayed is converted into RGB raw data through the format, the RGB raw data is filled into the frame buffer, and finally the RGB raw data are transmitted to the LCD screen through 24 data lines of the RGB. And when the data lines simulate the control lines of the EPD, the area corresponding to the frame buffer becomes large. The whole area is frame buffer, but the inner layer and the outer layer are relatively independent, and the outer layer is taken as an RGB controller, belongs to the output area of data, and is an analog area of control signals for EPD display. The EPD screen can be successfully lit as long as the signal simulation is correct.

Description

Method for simulating EPD screen interface by RGB interface

Technical Field

The application relates to the technical field of electronic display screen interfaces, in particular to a method for simulating an EPD screen interface by an RGB interface.

Background

In the prior art, an optical element electrophoretic Ink, or electronic Ink, used in electronic paper display [ Electronic Paper Displays, EPD ] imaging technology is created by Eink. The display technology is that colored charged balls are utilized, and the charged balls are moved in a liquid state environment by an external electric field to display different colors. In addition, the bistable technology in the bistable display screen can continuously stay on the display screen without disappearing in the state that the power supply is completely removed. In practical applications, this represents that the electronic book only needs to consume power when the picture changes. For example, when we read using an electronic book, only when turning pages, power is consumed, and no power is consumed at all during reading. Especially when the electronic book enters a standby state, the still picture existing throughout can be seen slightly for two times. In contrast, conventional LCD screens require updating the display at speeds greater than 30fps per second, whether or not a new display is displayed. The bistable characteristic of the EInk enables the electronic paper display screen to greatly reduce the consumption of a power supply, which is also a main reason that the electronic paper book has longer battery endurance. Electronic ink consists of millions of tiny microcapsules, approximately equivalent in diameter to human hair. Each microcapsule contains positively charged white particles and negatively charged black particles suspended in a clear liquid. When the positive or negative electric field is turned on, the corresponding particles move to the top of the microcapsules, and the user can see a white or black image on the surface.

The technical scheme close to the application is that the standard EPD controller drives the EPD screen to display, such as JZ4775 SOC, which is a product of Beijing jun integrated circuit Co., ltd., and can stably support various EPD manufacturer interfaces. Firmware parsing, including waveform, can be accomplished by the controller.

However, in the market at present, the types of SOCs (abbreviations of System on Chip), called System On Chip (SOC), are numerous, and most of display types of SOCs are standard for TFT LCD panel support, including RGB, SLCD, MIPI interface and the like. However, none of these SOCs include a controller for the EPD, resulting in the EPD screen not being operational on these SOCs, and resulting in such SOCs lacking support for the EPD screen class.

The common terminology in the prior art is as follows:

1 RGB interface: the common data communication interface of a general TFT liquid crystal display panel is generally divided into a typical display parallel port communication mode composed of a series of interfaces of RGB565, RGB666, RGB888 and the like according to the color bit difference of the liquid crystal panel, including data, CLK, data enable, line synchronization, frame synchronization and the like.

2 EPD: chinese names, called electrodeposition or Electrophoretic display (E-Paper), are display effects of different colors by turning or moving particles in a liquid by an applied electric field using black/white charged balls immersed in the liquid. Based on this property, the display panel of the EPD may be fabricated on a glass, metal or plastic substrate.

3 WAVEFORM: the waveform is a waveform file, typically in the format of wbf or bin, produced by the EPD screen manufacturer based on the characteristics of each model screen. Stored in the file is an encrypted/compressed data, which is ultimately used for the voltage data required for the screen display, including:

00, representing a voltage of 0V.

01, representing a 15V voltage.

10, representing a voltage of-15V.

And 11, invalidating data and streaming.

Disclosure of Invention

In order to solve the above problems, the present method aims at: aiming at the defects in the situation, the data and signals are simulated by utilizing a more universal RGB interface on the display type SOC, so that the normal display of the EPD screen can be supported.

Specifically, the present application provides a method for simulating an EPD screen interface by an RGB interface, the method comprising the steps of:

s1, hardware setting:

connecting the 6 data lines of 16-21 in the RGB interface to corresponding control lines of the EPD as analog output;

s2, setting software drivers:

s2.1, in the process of lighting the LCD by using a software-driven RGB interface, using a linux kernel frame as a frame buffer driver, wherein the software driver belongs to standard codes of the linux kernel, and realizes the function of lighting an EPD screen on the basis, and the frame buffer is a standard driving frame for displaying the LCD in the linux kernel, can display an image which a user layer wants to display on the LCD screen according to the requirement, converts data to be displayed into raw data of RGB through a format, fills the raw data into the frame buffer, and finally transmits the raw data to the LCD screen through 24 data lines of RGB;

s2.2, after the data line simulates the control line of the EPD, the frame buffer is enlarged, namely the frame buffer is divided into an outer layer area and an inner layer area, wherein the outer layer area is an effective area of RGB display, and the inner layer area is an effective area of EPD display; in the outer layer area, the signal output by 0-15pin is invalid, and 16-21pin is used as an analog control signal, and in the outer layer area, the control signal required by the EPD screen is output;

in the inner layer region, 0-15pin is an effective data signal displayed by EPD, and 16-21pin is an analog control signal, and no effective data information is transmitted in the inner layer region; the whole area is a frame buffer, but the inner layer area and the outer layer area are relatively independent, and the outer layer area is taken as an RGB controller, belongs to an output area of data, and is an analog area of a control signal for EPD display;

s2.3, the EPD screen can be successfully lit as long as the signal simulation is correct.

In the step S1, the step of outputting includes:

control lines connected to lcd_d16 to lcd_d21:

LCD_D16 corresponds to the CKV interface;

LCD_D17 corresponds to the Mode interface;

LCD_D18 corresponds to the XLE interface;

lcd_d19 corresponds to XOE interface;

lcd_d20 corresponds to XSTL interface;

lcd_d21 corresponds to the SPV interface.

In the step S2.1, the raw data converted into RGB is that the user layer picture is generally jpg, bmp, png format, and the raw data from which RGB888 is converted is filled into frame buffer.

In step S2.2, the frame buffer is enlarged, that is, the EPD screen with the size of the inner layer area is lit, and the frame buffer with the size of the outer layer area needs to be constructed, which is equivalent to being enlarged compared with the frame buffer effectively displayed.

In the step S2.3, the output of 16-21pin is simulated according to the requirement of the control signal of EPD, each pixel occupies 24 bits in the frame buffer of RGB888 format, wherein 0-15 bits fill in valid data of EPD, 16-21 bits fill in data in bit positions in corresponding pixel according to the requirement of the control signal of EPD, and invalid data is filled with 0.

Thus, the present application has the advantages that: the method is simple, can utilize a universal RGB interface to simulate data and signals, so that the method can support normal display of the EPD screen, make up a display short board of the SOC chip, and improve the competitiveness and coverage range of the market.

Drawings

The accompanying drawings, which are included to provide a further understanding of the application and are incorporated in and constitute a part of this specification, illustrate and together with the description serve to explain the application.

FIG. 1 is a schematic flow chart of the method of the present application.

Fig. 2 is a schematic diagram of a data line connection.

Fig. 3 is a schematic diagram of the region in frame buffer.

Detailed Description

In order that the technical content and advantages of the present application may be more clearly understood, a further detailed description of the present application will now be made with reference to the accompanying drawings.

As shown in fig. 1, the present application relates to a method for simulating EPD screen interface by using RGB888 interface mode of general SOC as an example to describe the EPD display simulation flow.

In general, the RGB888 interface includes 24 pins including a data line, a clock signal line, a row synchronization signal line, a frame synchronization signal line, a data enable signal line, and the like.

The interface of the EPD (except for the power supply interface) includes 16 data lines, an output mode select line, a clock source drive line, a clock gate drive line, a gate enable signal line, a source drive latch enable line, and a source drive output enable line, for example, a wep technology 7-inch color EPD screen.

From the interface, the two types of the control signal lines are relatively large in difference, particularly, the control signal lines except the data lines basically have no category with the same function, so that the driving modes of the two types of the screens are greatly different.

If the RGB control lines are used to simulate the EPD control lines, the possibility is not high, because the LCD control lines are all functionally fixed, when the SOC display controller completes the configuration of the RGB control lines, the output waveforms of the control lines are fixedly transmitted according to the RGB protocols, and the EPD control line waveform simulation cannot be performed, so that the path is not enabled.

Another way is to look at the data lines, the RGB888 interface has 24 data lines and the EPD has 16 data lines, so that the RGB interface can still have 8 data lines left, but the eight data lines are discretionary and have the ability to simulate the minimum unit waveform arbitrarily (the minimum unit is the period of the clock signal line). It can be asserted that simulating the control lines of an EPD can be achieved as long as the number of control signal lines of the EPD is equal to or less than the number of data lines remaining in RGB. While only 6 control lines are needed for EPD in this example, this can be true. Thus, the method employs a connection method as shown in fig. 2, in which:

control lines connected to lcd_d16 to lcd_d21:

LCD_D16 corresponds to the CKV interface;

LCD_D17 corresponds to the Mode interface;

LCD_D18 corresponds to the XLE interface;

lcd_d19 corresponds to XOE interface;

lcd_d20 corresponds to XSTL interface;

lcd_d21 corresponds to the SPV interface.

As shown in fig. 1, the method comprises the steps of:

s1, hardware setting:

s2, setting software drivers:

s2.1, in the software-driven RGB interface lighting LCD, using a linux kernel frame as a frame buffer driver, wherein the software driver belongs to standard codes of the linux kernel, the method does not need to use the linux kernel frame, and the related driver used in the embodiment uses the frame buffer to explain the simulation principle; the function of lighting an EPD screen is realized on the basis, the frame buffer is a standard driving frame for LCD display in a linux kernel, an image to be displayed by a user layer can be displayed on the LCD screen according to the requirement, the data to be displayed is converted into RGB raw data through a format, the user layer picture is generally jpg, bmp, png and other formats, the original data from which the RGB888 is required to be converted is filled into the frame buffer, and particularly, how to convert the original data into the frame buffer belongs to the prior art, the original data is filled into the frame buffer, and finally, the original data is transmitted to the LCD screen through 24 RGB data lines;

s2.2, after the data line simulates the control line of the EPD, the frame buffer is enlarged, namely the frame buffer is divided into an outer layer area and an inner layer area, and as seen from the two areas shown in FIG. 3, the outer layer area is an effective area of RGB display, and the inner layer area is an effective area of EPD display;

in the outer layer area, the signal output by 0-15pin is invalid, and 16-21pin is used as an analog control signal, and in the outer layer area, the control signal required by the EPD screen is output;

in the inner layer region, 0-15pin is an effective data signal displayed by EPD, and 16-21pin is an analog control signal, and no effective data information is transmitted in the inner layer region; the expansion, namely, the point is to lighten an EPD screen with the size of an inner layer region, and a frame buffer with the size of an outer layer region needs to be constructed, which is equivalent to expanding the frame buffer compared with the effective display;

the whole area is a frame buffer, but the inner layer area and the outer layer area are relatively independent, and the outer layer area is taken as an RGB controller, belongs to an output area of data, and is an analog area of a control signal for EPD display;

s2.3, the EPD screen can be successfully lit as long as the signal simulation is correct. According to the requirement of the control signal of the EPD, the output of 16-21pin is simulated, each pixel occupies 24 bits in the frame buffer in RGB888 format, wherein 0-15 bits are filled with effective data of the EPD, 16-21 bits are filled with data according to the requirement of the control signal of the EPD, and the bit in the corresponding pixel is filled with invalid data by 0.

Finally, on the Beijing jun positive model X2000 SOC platform, the scheme is actually simulated and successfully lights up the EPD screen, and the scheme is proved to be successful and effective.

The application can be applied to all platforms, because the LCD controllers of all the platforms are different and the registers are different, the specific coding methods for lighting RGB are not the same, but only the interfaces are consistent, 24 data lines and VSYNC, HSYNC, CLK, DE control lines are all provided, and the application mainly aims to protect the method that the external interfaces of RGB can simulate and output EPD data and light an EPD screen.

The above description is only of the preferred embodiments of the present application and is not intended to limit the present application, and various modifications and variations can be made to the embodiments of the present application by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims

1. A method of an RGB interface to emulate an EPD screen interface, the method comprising the steps of:

s1, hardware setting:

s2, setting software drivers:

in the inner layer region, 0-15pin is an effective data signal displayed by EPD, and 16-21pin is an analog control signal, and no effective data information is transmitted in the inner layer region;

2. The method of simulating an EPD screen interface according to claim 1, wherein in step S1, the step of outputting as a simulation includes:

control lines connected to lcd_d16 to lcd_d21:

LCD_D16 corresponds to the CKV interface;

LCD_D17 corresponds to the Mode interface;

LCD_D18 corresponds to the XLE interface;

lcd_d19 corresponds to XOE interface;

lcd_d20 corresponds to XSTL interface;

lcd_d21 corresponds to the SPV interface.

3. The method of claim 1, wherein in step S2.1, the raw data converted into RGB is that the user layer picture is generally jpg, bmp, png format, and the raw data from which RGB888 is converted is filled into frame buffer.

4. The method of simulating an EPD screen interface according to claim 1, wherein in step S2.2, the frame buffer is enlarged, i.e. an EPD screen with an inner area size is highlighted, and a frame buffer with an outer area size needs to be constructed, which is enlarged compared with the frame buffer for effective display.

5. A method for simulating an EPD screen interface according to claim 3, wherein in step S2.3, the output of 16-21pin is simulated according to the requirement of the control signal of EPD, each pixel occupies 24 bits in the frame buffer of RGB888 format, wherein 0-15 bits fill valid data of EPD, 16-21 bits fill data in bit positions in the corresponding pixel according to the requirement of the control signal of EPD, and invalid data is filled with 0.