tft display interface quotation

Quote: This display uses the NT57860 driver IC. I"m using the TC358860 eDP-to-MIPIDSI bridge chip, but I"m not sure whether it can drive this display panel. Is it possible to share the datasheet of this NT57860 driver IC? That way I"m able to verify that. Thanks in advance, With kind regards

Leadtek has paid great efforts on research and development of TFT-LCM, especially on its application of consumable and industrial products. The sizes of LCM includes 1.4”, 2.4”, 3.5", 3.51", 4.3", 4", 5", 7", 8", 10.1” and 11.6". And among them the 3.5”, 4.3", 5", 7” and 10.1" LCM has achieved the leading level of the industry, and mainly applied to vehicle-applications, tablet PCs, smartphones, medical equipment, measurement equipment, E-books, EPC and industrial products, and provides powerful and reliable supports on supplies and qualities. We are cooperating with famous foreign companies on research and developments, and will bring out the series products of industrial control. Also, we explore the overseas market, and build up a long-term relationship with our overseas partners and agents, Leadtek products will be worldwide in the near future.

TFT displays are full color LCDs providing bright, vivid colors with the ability to show quick animations, complex graphics, and custom fonts with different touchscreen options. Available in industry standard sizes and resolutions. These displays come as standard, premium MVA, sunlight readable, or IPS display types with a variety of interface options including HDMI, SPI and LVDS. Our line of TFT modules include a custom PCB that support HDMI interface, audio support or HMI solutions with on-board FTDI Embedded Video Engine (EVE2).

The display is a critical component in every project, impacting the case, firmware, electrical design, user interface, and even battery life. For these reasons, and because it is the most visible component of your product, it must be approved by the mechanical design team, management and marketing.Before these teams can approve, they need to see it in action. But it can take days or weeks to connect a display to your platform, initialize it and build a code library able to create believable demonstrations. Meanwhile, the whole project is on hold.Our 8051 development kit / demonstration board can solve this problem. Use it to get the display seen, demonstrated and approved for your project.

ER-DBT032-3 is a microcontroller 8051(80C51) demonstration and development kit for ER-TFT032-3.1 product that is 3.2 inch tft lcd display with ILI9341 controller.The kit includes MCU board controlled by STC12LE5A60S2,ISP(In System Programming) with USB port and cable to customize the demonstration that includes your own bitmap images,personalized fonts,symbols,icons and burn sketches,microSD card that is written graphic and text into it,the power adaptor,the adaptor board with various pitch dimension used to connect MCU board and display.Optional for 8080 8-bit,8080 16-bit parallel interface and 3-wire,4-wire serial interface.

For a digital picture frame i would like to use the MSP430 to connect a 20" TFT LCD display (Resolution 1600 X 1200) via SPI. Do you think this is doable? Is there a LCD controller that can support such a high resolution with SPI? In my research so far i have found some projects for small displays such as this:

This graphic display module is a 2.4" diagonal, full color TFT. Suitable for embedded applications, it is low-power, uses a white LED backlight, and has an integrated touch panel which has its connection brought out to the main TAB connector for the display.

It has an on-board controller and 3v single voltage for supply and logic (backlight not included), so you can easily use any modern microcontroller to interface with this display. It uses an 8 or 16 bit parallel interface, specified via connections to the display.

The connector on the CFAF240320K-024T-TS is a flex tail mated with a "COG" (chip on glass) display construction. This style of connector is designed to be soldered directly to corresponding pads on your PCB by using a hot-bar soldering machine. High volume contract manufacturers will be familiar with this type of construction and its assembly methods. There are hot-bar soldering machines made that are designed for prototype, rework or repair work of TAB connections.

We are changing our TFT part numbers to have them better describe the parts being ordered. The change should be complete for all TFT modules shipping within the next six months.

Displays have over time, emerged as one of the best ways to drive user interactions on any device. They make it easy to collect inputs and present information (outputs) to users in a graphical, easy to understand format. This usefulness has led to improvements in their quality, with improved resolution and low power features, but almost little has changed when it comes to the complexity of creating beautiful user interfaces for them. This is why the team at STONE Tech created the STVC035WT-01 intelligent Smart display which we will explore for today’s tutorial.

The STONE STVC035WT-01 display is a 16-bit, 3.5″ display with a 320×480 (RGB) resolution, has a 49.0 x 73.4mm viewing area, and pixel spacing of 0.1905mm×0.0635mm (H×V). The display is a Class A industry Panel with an Industry level 4 wire resistance based touch screen, all layered on an integrated CPU, driver, and flash memory with several communication interfaces to enable it to connect to data sources like microcontrollers. For communication with a microcontroller, the display supports serial communication protocols likeUART/TTL, RS232, and RS485, ensuring it can communicate with any kind of microcontroller or industrial computers. The UART/TTL pin on the Display supports both 3.3v/5v logic level which adds another layer of ease to the use of the display as users need not worry about the need for logic level shifters when building using a microcontroller that operates on either of the voltage level mentioned.

One of the major benefits of using this display is its compatibility with the STONE TOOL GUI Designer which allows the development of User Interfaces in a fast and easy manner.

To demonstrate the capabilities of the display, we will build a heart rate monitor using an Arduino Uno with the MAX30100 pulse oximetry and heart rate sensor. The Arduino will serve as the brain of the project and perform the simple task of obtaining the heart rate and blood oxygen data from the MAX30100, displaying it on the screen.

At the end of this tutorial, you would know how to interface Arduino boards with the STONETech displays, and also how to interface sensors like the MAX30100 with the Arduino.

Our development process for today’s project will follow this outline. We will first create the GUI for the project after which we will proceed to write the firmware to interface the microcontroller with the display.

As mentioned during the introduction, today’s tutorial will focus on creating a heart rate and Oxygen-level monitoring system using the display and to get things started, we create the GUI image (shown below) using Photoshop.

The design is quite simple, we illustrate label elements to hold the date, the project title, and the values from the microcontroller. The values from the microcontroller include; the status of the connection between the microcontroller and the display, the heart rate, and the oxygen levels.

1. With the software downloaded on your computer, launch it and go to File>New Project. This will launch the “New Project dialog box ” where you will be expected to fill in the details of your display, set the storage path, and the name of your project. Since we will use the STVC035WT-01 display which has a  resolution of 320*480 and a default flash space size of 128Mbyte (expandable to 1024MByte), I have entered its details as shown in the image below. If you are using any of the other StoneTech displays, you will need to enter the details of that display instead.

4. Next, we add fonts to the project’s assets to determine how texts appear on the display. Right-click the “Font” file, and select the appropriate font to add to the project. For this tutorial, we will use the ASCII 24 by 48 font. With that done we are now ready to begin adding the GUI elements.

5. We will only use the “Text Display” GUI element since the display is only meant to display data from the MAX30100. The text display elements are capable of holding texts that can be changed programmatically by updating the data stored in their memory addresses. Add text displays on the lines as highlighted in the image below. Also, create a text display for the day-time section at the top of the display image to help users note the date/time each reading was observed.

6. Next, we set the properties of the text displays especially their memory addresses. The properties of each GUI element will be available on the right-hand side of your PC screen after clicking on the element. Note the memory address down as it will play an important role later.

7. With all of these done, we compile the GUI and upload it to the screen. To do this, click on button 1 in the image below to Compile the GUI design and click on button 2 to upload the GUI to your display.

Uploading the GUI display requires you either connect the display directly to your computer or you put the GUI on a flash drive and plug the flash drive into the USB port of the display. Because of the little complexity associated with the second option, we will be going with it.

Plug the USB flash drive into the computer then click the “Download to u-disk” button on the STONE GUI TOOL.With the “download to u-disk” process complete, pull out the USB flash disk, insert it into the USB interface of the display module and wait for the completion of the upgrade. When the upgrade is completed, there will be a prompt sound.

The model of the STONE display being used for this tutorial communicates via RS232, as such, to be able to interface the display with the Arduino, we have to connect it through a MAX3232 chip. This extra requirement can be avoided by using one of the STONE displays with a TTL interface.

Due to the simplicity embedded in the design of STONETECH displays, the microcontroller’s interaction with any of the GUI components is usually via the “memory address” of each component. for instance, to send a message to the display from the microcontroller (the Arduino in this case), the message has to be published to the memory address of the GUI Component (in this case, the text-display component). The same holds for GUI Components that are meant to send data to the microcontroller, as the microcontroller has to poll their memory address to obtain information from them. As a result of these, we need to obtain the memory address of all the GUI components before proceeding. For each GUI component, the memory address is usually listed among the properties of the component, under the property toolbar, at the right-hand side of the STONE TOOL interface.

With this obtained, we can now proceed to write the code for the project. One of the good things about using the STONETech displays is the fact that you don’t need a library to write code for them because of their simplicity, but since we will use serial communication, we will use the software serial library to avoid having to use the hardware serial

Looking for a SPI TFT display? Need a perfectly small SPI TFT for your next Arduino project? Check out our line of full-color SPI TFT LCD modules. Our SPI TFT displays are between 2 and 3.5 inch.

Displays much larger than 3.5 inches or with higher resolutions aren"t usually driven via SPI because it"s not fast enough to provide good frame rates for larger displays. But for small TFT displays, SPI is a perfectly suited interface.

We have over two dozen TFT LCD display modules to choose from. All of them are full-color graphic displays. Unlike standard monochrome character displays, you can create complex images for imaginative user experiences. Thin and light, these are ideal for handheld devices, communications equipment, information displays, and test and measurement equipment.

Listed by the diagonal size of the active area (the usable area for lit pixels), our TFT display sizes range from 1.3 inches to 10.1 inches. Choose from six different interfaces, many of our TFT modules have more than one interface available. Arduino users should select modules with SPI for fast and easy communications to add color graphics to their projects.

Contrast ratio is the difference between a pixel that is lit or dark. Standard STN LCD displays typically have a 10:1 contrast ratio while TFT displays are 300:1 and up, so details stand out and text looks extra sharp. For standard STN displays, you must choose a display limited to a specific viewing angle (12, 3, 6 or 9 o"clock) while TFTs can have a viewing cone greater than 160 degrees.

To speed up your design time, we sell carrier boards and demonstration kits for selected modules. For outdoor use, be sure to look at our sunlight readable displays.

ASI-T-17711A1SPN/D is a 1.77 inch transflective TFT with a resolution of 160 x 128, SPI interface and with a brightness of 110 Nits; viewable in direct sunlight.

ASI-T-20043A5PMN/AY is a 2.0 inch TFT with a resolution of 480 x 360, 3W SPI+16 bit RGB or MIPI interface, IPS all view, with a high brightness of 500 Nits.

ASI-T-240DA8BN/D is a 2.4 inch high brightness TFT with a resolution of 240 X 320, CPU 16-bit interface and with a brightness of 800 Nits; viewable in direct sunlight.

ASI-T-240DA10SMN/AQ is a 2.4 inch high brightness TFT with a resolution of 240 x 320, SPI & MCU interface, IPS all-angle view and with a brightness of 1000 Nits; viewable in direct sunlight. It also features an extra wide operating temperatures of -30 to +80C; perfect for extreme environmental applications.

ASI-T-240DAKBN/D is a 2.4 inch high brightness TFT with a resolution of 240 x 320, MCU interface and with a brightness of 1000 Nits; viewable in direct sunlight.

ASI-T-283DAKCRN/A is a 2.83 inch high brightness TFT with a resolution of 240 x 320, CPU, RGB, SPI interface and with a brightness of 1000 Nits; viewable in direct sunlight

ASI-T-3501RA1EN/A is a 3.5 inch TFT with a resolution of 480 x 640, 18 bit RGB, All View interface and with a brightness of 120 Nits; viewable in direct sunlight

ASI-T-3501RA1EN/D is a 3.5 inch TFT with a resolution of 480 x 640, 18-bit DBI Type B, All View interface and with a brightness of 120 Nits; viewable in direct sunlight

ASI-T-350EA8RCY6/A is a 3.5 inch high brightness TFT with a resolution of 320 x 240, 24-bit Parallel RGB/Serial RGB/CCIR/YUV interface and with a brightness of 850 Nits; viewable in direct sunlight with Capacitive Touch Panel

ASI-T-350EA10SRN/A is a 3.5 inch TFT with a resolution of 320 x 240, SPI & RGB interface and with a high brightness of 1,000 Nits and wide temperature range of -30 - +85 C.

The provided display driver example code is designed to work with Microchip, however it is generic enough to work with other micro-controllers. The code includes display reset sequence, initialization and example PutPixel() function.

Please see the DT028CTFT for reference designs. The schematics between the A and the C are the same with the exception that the A does not have the IPS interface.

The DT022BTFT uses the same connections as the DT022CTFT, with the exception of the backlight (which has connections shown in the Displaytech datasheet).

The provided display driver example code is designed to work with Microchip, however it is generic enough to work with other micro-controllers. The code includes display reset sequence, initialization and example PutPixel() function. Keep the default values for all registers in the ILI9341, unless changed by the example code provided.

4-wire 8-bit Serial Data Interface II is the correct mode to use based on the microprocessor pins available. This mode is closest to standard SPI port operation with a few minor exceptions.

Note that the WR pin becomes the D/CX signal in serial mode. CS is used to initiate a data transfer by pulling it low. At the end of the data transfer, pull the CS pin high to complete the transaction. The timing diagram indicates that you can pull the CS pin high in between the command byte and data bytes within a transfer, but it is unlikely needed if the display is the only device on the SPI bus. To keep things simple, we suggest to leave it low during the entire transaction.

The Capacitive touch panel is activated with anything containing an inductive load such as a finger or stylus. It allows for multi-touch options. When using the capacitive touch screen, the display needs a separate controller to interface with the touch panel. The display for capacitive touch is brighter since the touch panel is transparent.

The Transmissive polarizer is best used for displays that run with the backlight on all the time. This polarizer provides the brightest backlight possible. If you have a need for a bright backlight with lower power drain, transmissive is a good choice for this TFT LCD display.

Focus LCDs can provide many accessories to go with your display. If you would like to source a connector, cable, test jig or other accessory preassembled to your LCD (or just included in the package), our team will make sure you get the items you need.Get in touch with a team member today to accessorize your display!

Focus Display Solutions (aka: Focus LCDs) offers the original purchaser who has purchased a product from the FocusLCDs.com a limited warranty that the product (including accessories in the product"s package) will be free from defects in material or workmanship.

All staff of our company inherit and carry forward the spirit of "honesty, innovation and pragmatism", and sincerely look forward to cooperating with all new and old customers, peer enterprises and people from all walks of life who are concerned about the development of 15.6 Inch TFT LCD Display 1920*1080 with Edp Interface industry to seek common development. Our fully experienced engineer and extensive application expertise make us as a valued partner for the project development and production with customer-specific solutions. We make every effort to build a corporate culture full of personality, continuous optimization, cohesion of the whole staff, and enhance the core competitiveness of the enterprise.

TFT LCD, acronym for Thin Film Transistor Liquid Crystal Display, is a technology developed for improve image quality and has countless consumer and industrial uses.

Specifically, within TFT monitors, liquid crystals allow faster and smoother state transitions while saving power, resulting in high image quality on the display, which appears without flickering or bright irregularities (unlike simpler LCD screens).

TFT screens can be of different sizes, ranging from small 3.5" screens to large displays, and can also be identified by their area of use or by certain special features and applications, such as multitouch.

TFT displays are always clearly visible in sunlight, making them particularly suitable for outdoor use. This type of display is also particularly light, thin and energy-efficient, as well as being relatively inexpensive in relation to the technical features offered.

Digimax has an extensive catalogue ofTFT screens from 7" to 23", LCD displays and professional monitors capable of handling a high number of pixels to enable high image quality, high resolution and a screen without glare or flicker.

TFT technology is now a consolidated reality for the choice of monitors, screens and industrial displays: following this market evolution, Digimax offers the latest generation of TFT touch screen solutions, multi touch monitors and transparent displays able to offer the right option for every need.

We offer both standard and customised TFT LCDs through strategic partnerships with leading international suppliers and brands: Ampire displays, Raystar monitors and DLC screens, as well as RockTech, RockTouch and AUO touch screens.

Together with Digimax consultancy, a specific service is also available to configure TFT kits consisting of a TFT LCD monitor and matching PC board: it is possible to customise CPU and coverlens, touch technology used and connection wiring between motherboard and display.

A thin-film-transistor liquid-crystal display (TFT LCD) is a variant of a liquid-crystal display that uses thin-film-transistor technologyactive matrix LCD, in contrast to passive matrix LCDs or simple, direct-driven (i.e. with segments directly connected to electronics outside the LCD) LCDs with a few segments.

In February 1957, John Wallmark of RCA filed a patent for a thin film MOSFET. Paul K. Weimer, also of RCA implemented Wallmark"s ideas and developed the thin-film transistor (TFT) in 1962, a type of MOSFET distinct from the standard bulk MOSFET. It was made with thin films of cadmium selenide and cadmium sulfide. The idea of a TFT-based liquid-crystal display (LCD) was conceived by Bernard Lechner of RCA Laboratories in 1968. In 1971, Lechner, F. J. Marlowe, E. O. Nester and J. Tults demonstrated a 2-by-18 matrix display driven by a hybrid circuit using the dynamic scattering mode of LCDs.T. Peter Brody, J. A. Asars and G. D. Dixon at Westinghouse Research Laboratories developed a CdSe (cadmium selenide) TFT, which they used to demonstrate the first CdSe thin-film-transistor liquid-crystal display (TFT LCD).active-matrix liquid-crystal display (AM LCD) using CdSe TFTs in 1974, and then Brody coined the term "active matrix" in 1975.high-resolution and high-quality electronic visual display devices use TFT-based active matrix displays.

The liquid crystal displays used in calculators and other devices with similarly simple displays have direct-driven image elements, and therefore a voltage can be easily applied across just one segment of these types of displays without interfering with the other segments. This would be impractical for a large display, because it would have a large number of (color) picture elements (pixels), and thus it would require millions of connections, both top and bottom for each one of the three colors (red, green and blue) of every pixel. To avoid this issue, the pixels are addressed in rows and columns, reducing the connection count from millions down to thousands. The column and row wires attach to transistor switches, one for each pixel. The one-way current passing characteristic of the transistor prevents the charge that is being applied to each pixel from being drained between refreshes to a display"s image. Each pixel is a small capacitor with a layer of insulating liquid crystal sandwiched between transparent conductive ITO layers.

The circuit layout process of a TFT-LCD is very similar to that of semiconductor products. However, rather than fabricating the transistors from silicon, that is formed into a crystalline silicon wafer, they are made from a thin film of amorphous silicon that is deposited on a glass panel. The silicon layer for TFT-LCDs is typically deposited using the PECVD process.

Polycrystalline silicon is sometimes used in displays requiring higher TFT performance. Examples include small high-resolution displays such as those found in projectors or viewfinders. Amorphous silicon-based TFTs are by far the most common, due to their lower production cost, whereas polycrystalline silicon TFTs are more costly and much more difficult to produce.

The twisted nematic display is one of the oldest and frequently cheapest kind of LCD display technologies available. TN displays benefit from fast pixel response times and less smearing than other LCD display technology, but suffer from poor color reproduction and limited viewing angles, especially in the vertical direction. Colors will shift, potentially to the point of completely inverting, when viewed at an angle that is not perpendicular to the display. Modern, high end consumer products have developed methods to overcome the technology"s shortcomings, such as RTC (Response Time Compensation / Overdrive) technologies. Modern TN displays can look significantly better than older TN displays from decades earlier, but overall TN has inferior viewing angles and poor color in comparison to other technology.

Most TN panels can represent colors using only six bits per RGB channel, or 18 bit in total, and are unable to display the 16.7 million color shades (24-bit truecolor) that are available using 24-bit color. Instead, these panels display interpolated 24-bit color using a dithering method that combines adjacent pixels to simulate the desired shade. They can also use a form of temporal dithering called Frame Rate Control (FRC), which cycles between different shades with each new frame to simulate an intermediate shade. Such 18 bit panels with dithering are sometimes advertised as having "16.2 million colors". These color simulation methods are noticeable to many people and highly bothersome to some.gamut (often referred to as a percentage of the NTSC 1953 color gamut) are also due to backlighting technology. It is not uncommon for older displays to range from 10% to 26% of the NTSC color gamut, whereas other kind of displays, utilizing more complicated CCFL or LED phosphor formulations or RGB LED backlights, may extend past 100% of the NTSC color gamut, a difference quite perceivable by the human eye.

In 2004, Hydis Technologies Co., Ltd licensed its AFFS patent to Japan"s Hitachi Displays. Hitachi is using AFFS to manufacture high end panels in their product line. In 2006, Hydis also licensed its AFFS to Sanyo Epson Imaging Devices Corporation.

A technology developed by Samsung is Super PLS, which bears similarities to IPS panels, has wider viewing angles, better image quality, increased brightness, and lower production costs. PLS technology debuted in the PC display market with the release of the Samsung S27A850 and S24A850 monitors in September 2011.

TFT dual-transistor pixel or cell technology is a reflective-display technology for use in very-low-power-consumption applications such as electronic shelf labels (ESL), digital watches, or metering. DTP involves adding a secondary transistor gate in the single TFT cell to maintain the display of a pixel during a period of 1s without loss of image or without degrading the TFT transistors over time. By slowing the refresh rate of the standard frequency from 60 Hz to 1 Hz, DTP claims to increase the power efficiency by multiple orders of magnitude.

Due to the very high cost of building TFT factories, there are few major OEM panel vendors for large display panels. The glass panel suppliers are as follows:

External consumer display devices like a TFT LCD feature one or more analog VGA, DVI, HDMI, or DisplayPort interface, with many featuring a selection of these interfaces. Inside external display devices there is a controller board that will convert the video signal using color mapping and image scaling usually employing the discrete cosine transform (DCT) in order to convert any video source like CVBS, VGA, DVI, HDMI, etc. into digital RGB at the native resolution of the display panel. In a laptop the graphics chip will directly produce a signal suitable for connection to the built-in TFT display. A control mechanism for the backlight is usually included on the same controller board.

The low level interface of STN, DSTN, or TFT display panels use either single ended TTL 5 V signal for older displays or TTL 3.3 V for slightly newer displays that transmits the pixel clock, horizontal sync, vertical sync, digital red, digital green, digital blue in parallel. Some models (for example the AT070TN92) also feature input/display enable, horizontal scan direction and vertical scan direction signals.

New and large (>15") TFT displays often use LVDS signaling that transmits the same contents as the parallel interface (Hsync, Vsync, RGB) but will put control and RGB bits into a number of serial transmission lines synchronized to a clock whose rate is equal to the pixel rate. LVDS transmits seven bits per clock per data line, with six bits being data and one bit used to signal if the other six bits need to be inverted in order to maintain DC balance. Low-cost TFT displays often have three data lines and therefore only directly support 18 bits per pixel. Upscale displays have four or five data lines to support 24 bits per pixel (truecolor) or 30 bits per pixel respectively. Panel manufacturers are slowly replacing LVDS with Internal DisplayPort and Embedded DisplayPort, which allow sixfold reduction of the number of differential pairs.

The bare display panel will only accept a digital video signal at the resolution determined by the panel pixel matrix designed at manufacture. Some screen panels will ignore the LSB bits of the color information to present a consistent interface (8 bit -> 6 bit/color x3).

With analogue signals like VGA, the display controller also needs to perform a high speed analog to digital conversion. With digital input signals like DVI or HDMI some simple reordering of the bits is needed before feeding it to the rescaler if the input resolution doesn"t match the display panel resolution.

Kawamoto, H. (2012). "The Inventors of TFT Active-Matrix LCD Receive the 2011 IEEE Nishizawa Medal". Journal of Display Technology. 8 (1): 3–4. Bibcode:2012JDisT...8....3K. doi:10.1109/JDT.2011.2177740. ISSN 1551-319X.

Brody, T. Peter; Asars, J. A.; Dixon, G. D. (November 1973). "A 6 × 6 inch 20 lines-per-inch liquid-crystal display panel". 20 (11): 995–1001. Bibcode:1973ITED...20..995B. doi:10.1109/T-ED.1973.17780. ISSN 0018-9383.

K. H. Lee; H. Y. Kim; K. H. Park; S. J. Jang; I. C. Park & J. Y. Lee (June 2006). "A Novel Outdoor Readability of Portable TFT-LCD with AFFS Technology". SID Symposium Digest of Technical Papers. AIP. 37 (1): 1079–82. doi:10.1889/1.2433159. S2CID 129569963.

Kim, Sae-Bom; Kim, Woong-Ki; Chounlamany, Vanseng; Seo, Jaehwan; Yoo, Jisu; Jo, Hun-Je; Jung, Jinho (15 August 2012). "Identification of multi-level toxicity of liquid crystal display wastewater toward Daphnia magna and Moina macrocopa". Journal of Hazardous Materials. Seoul, Korea; Laos, Lao. 227–228: 327–333. doi:10.1016/j.jhazmat.2012.05.059. PMID 22677053.

Display size, contrast, color, brightness, resolution, and power are key factors in choosing the right display technology for your application. However, making the right choice in how you feed the information to the display is just as vital, and there are many interface options available.

All displays work in a similar manner. In a very basic explanation, they all have many rows and columns of pixels driven by a controller that communicates with each pixel to emit the brightness and color needed to make up the transmitted image. In some devices, the pixels are diodes that light up when current flows (PMOLEDs and AMOLEDs), and in other electronics, the pixel acts as a shutter to let some of the light from a backlight visible. In all cases, a memory array stores the image information that travels to the display through an interface.

According to Wikipedia, "an interface is a shared boundary across which two separate components of a computer system exchange information. The exchange can be between software, computer hardware, peripheral devices, humans, and combinations of these. Some computer hardware devices such as a touchscreen can both send and receive data through the interface, while others such as a mouse or microphone may only provide an interface to send data to a given system.” In other words, an interface is something that facilitates communication between two objects. Although display interfaces serve a similar purpose, how that communication occurs varies widely.

Serial Peripheral Interface (SPI) is a synchronous serial communication interface best-suited for short distances. It was developed by Motorola for components to share data such as flash memory, sensors, Real-Time Clocks, analog-to-digital converters, and more. Because there is no protocol overhead, the transmission runs at relatively high speeds. SPI runs on one master (the side that generates the clock) with one or more slaves, usually the devices outside the central processor. One drawback of SPI is the number of pins required between devices. Each slave added to the master/slave system needs an additional chip select I/O pin on the master. SPI is a great option for small, low-resolution displays including PMOLEDs and smaller LCDs.

Philips Semiconductors invented I2C (Inter-integrated Circuit) or I-squared-C in 1982. It utilizes a multi-master, multi-slave, single-ended, serial computer bus system. Engineers developed I2C for simple peripherals on PCs, like keyboards and mice to then later apply it to displays. Like SPI, it only works for short distances within a device and uses an asynchronous serial port. What sets I2C apart from SPI is that it can support up to 1008 slaves and only requires two wires, serial clock (SCL), and serial data (SDA). Like SPI, I2C also works well with PMOLEDs and smaller LCDs. Many display systems transfer the touch sensor data through I2C.

RGB is used to interface with large color displays. It sends 8 bits of data for each of the three colors, Red Green, and Blue every clock cycle. Since there are 24 bits of data transmitted every clock cycle, at clock rates up to 50 MHz, this interface can drive much larger displays at video frame rates of 60Hz and up.

Low-Voltage Differential Signaling (LVDS) was developed in 1994 and is a popular choice for large LCDs and peripherals in need of high bandwidth, like high-definition graphics and fast frame rates. It is a great solution because of its high speed of data transmission while using low voltage. Two wires carry the signal,  with one wire carrying the exact inverse of its companion. The electric field generated by one wire is neatly concealed by the other, creating much less interference to nearby wireless systems. At the receiver end, a circuit reads the difference (hence the "differential" in the name) in voltage between the wires. As a result, this scheme doesn’t generate noise or gets its signals scrambled by external noise. The interface consists of four, six, or eight pairs of wires, plus a pair carrying the clock and some ground wires. 24-bit color information at the transmitter end is converted to serial information, transmitted quickly over these pairs of cables, then converted back to 24-bit parallel in the receiver, resulting in an interface that is very fast to handle large displays and is very immune to interference.

Mobile Industry Processor Interface (MIPI) is a newer technology that is managed by the MIPI Alliance and has become a popular choice among wearable and mobile developers. MIPI uses similar differential signaling to LVDS by using a clock pair and one to eight pairs of data called lanes. MIPI supports a complex protocol that allows high speed and low power modes, as well as the ability to read data back from the display at lower rates. There are several versions of MIPI for different applications, MIPI DSI being the one for displays.

Display components stretch the limitations of bandwidth. For perspective, the most common internet bandwidth in a residential home runs on average at around 20 megabits per second or 20 billion 1s and 0s per second. Even small displays can require 4MB per second, which is a lot of data in what is often a tightly constrained physical space.

Take the same PMOLED display with the 128 x 128 resolution and 16,384 separate diodes; it requires information as to when and how brightly to illuminate each pixel. For a display with only 16 shades, it takes 4 bits of data. 128 x 128 x 4 = 65,536 bits for one frame. Now multiply it by the 60Hz, and you get a bandwidth of 4 megabits/second for a small monochrome display.