minimum clock speed needed for lcd tft display in stock

Since the display includes the Ilitek ILI9320 controller, then your interface requirements are much lower, as the microcontroller no longer has to interface directly with the TFT and instead only talks to the controller chip via a simple interface: either SPI, which takes six wires: RS, CS, CLK, MOSI, MISO and RESET. Or you can use an 8080-compatible parallel interface which takes 13 wires: an 8-bit data bus, and RS, CS, WR, RD and RESET. (There are options to use larger data-buses, up to 18 bits, but I don"t recommend that for a low end microcontroller.)

There are two optional interfaces in which the microcontroller generates all of the clock signals (VSYNC, HSYNC and DOTCLK); you don"t want to do that since it would require a high-end controller.

So just about any microcontroller will do, however you need to have enough flash memory to hold whatever static items you want to display; for example if you are going to be displaying text then you will need to allocate arrays to store bitmaps for whatever fonts you will use. Even a small font can take 60KB.

Low voltage differential signaling (LVDS, also known as OpenLDI) thin-film transistor (TFT) liquid crystal (LCD) displays typically have a specified resolution and minimum required clock frequency to meet desired resolution. Normally, you will find this information listed in the display data sheet and won’t need to perform any calculations.

However, if you do not yet have access to your display data sheet and only know what resolution you want your system to support, you can estimate what clock frequency you need and determine which serializer/deserializer (SerDes) is appropriate for your application.

%Blanking: The blanking period, or the percentage of time when active video is not being displayed. As shown in Figure 1, it is represented horizontally as horizontal pulse width (HPW), horizontal back porch (HBP) and horizontal front porch (HFP). It is also represented vertically as vertical pulse width (VPW), vertical back porch (VBP) and vertical front porch (VFP).

The values for these blanking parameters are listed in display data sheets. The total blanking period varies from 3% to 39%. If your system uses reduced blanking, then you can estimate %Blanking at 10%. If you are not sure what blanking period your system uses, estimate around 20% and above to be conservative.

Frame rate (or refresh rate):the frequency at which consecutive images (frames) are displayed, and is measured in hertz or frames per second (fps). 60Hz is the most common frame rate, but this value can vary from 24Hz to 70Hz.

Throughput is another metric that you can use to determine whether or not a device will support your desired display resolution. The throughput is the effective payload of video data, and is derived from the required pixel clock frequency and color depth of your system, as shown in Equation 2:

Color depth: For a first-generation SerDes like the SN65LVDS93A, color depth is typically 24-bit red-green-blue (RGB) or 18-bit RGB for single pixel in, single pixel out (SISO) applications, and 48-bit RGB or 36-bit RGB for dual pixel in, dual pixel out (DIDO) applications.

The color depth will determine how many LVDS data lanes your display requires. SerDes serialize data at a rate of 7x the pixel clock frequency on each LVDS data lane. If the color depth is 24-bit RGB, then you will need four LVDS data lanes (there are an additional four bits used for control, which brings the total bit count to 28 bits) and can use a SerDes like the SN65LVDS93A. If the color depth is 18-bit RGB, then you will need three LVDS data lanes (there are an additional 3 bits used for control, which brings the total bit count to 21 bits) and can use a SerDes like the SN74LVDS84A or the SN65LVDS93A.

If the color depth is 48-bit RGB, then you will need eight LVDS data lanes (there are an additional 8 bits used for control, which brings the total bit count to 56 bits) and will need to use a device like the DS90C387 or DS90C189-Q1, which can output as many as eight LVDS data lanes.

When calculating the throughput for DIDO applications, you need to calculate the throughput for the odd pixels and even pixels separately and then add them together. For example, for a 48-bit DIDO application, the total required throughput would be 2 x Pixel Clock x 24.

Since the color depth is 24-bit RGB, you will need four LVDS data lanes. The SN65LVDS93A is a good fit for this application, since it has a pixel clock frequency range of 10MHz to 135MHz. Additionally, the maximum throughput for each LVDS data lane on this device is 135 x 7 = 945Mbps. Because this device has four LVDS data lanes, the total maximum throughput is 945 x 4 = 3780Mbps, which is higher than the minimum required throughput.

So the minimum pixel clock frequency to support a 2048 x 1536 resolution display is 208MHz. However, since this is a 48-bit DIDO application, there are actually two clocks: the frequency is split between them. Each clock must have a frequency of at least 104MHz.

Since the color depth is 48-bit RGB, you will need eight LVDS data lanes. The DS90C387 and DS90C187 are a good fit for this application, since they have a pixel clock frequency range of 32.5MHz to 112MHz (the DS90C387) and 25MHz to 105MHz (the DS90C187) for each channel in DIDO applications. Thus, if you don’t have access to the display data sheet yet, you can still estimate the required pixel clock frequency and throughput to support your desired resolution. If the SerDes does not meet these parameters, data on the display may display incorrectly, or not display at all.

I"m using an ILI9341-based LCD module, and the 4-wire SPI interface to communicate with it. According to the datasheet"s spec for this interface, I should be able to write at up to 1s/100ns(twc)=10Mhz, and read at up to 1s/150ns(trc)=6.66Mhz.

However, I am successfully writing and reading at 24Mhz! Not just for a simple test case, either. I"m doing complex graphics, mixed reads/writes for alpha blends, both 16-bit and 24-bit pixel writes, and so on - yet haven"t seen a single glitch. (Except those caused when I bump my dodgy old breadboard or jumper wires. That I"m using such poor connections, and it"s still working at this speed when not physically disturbed, make this even more amazing. The signal integrity must be horrible.)

In the past I"ve tried communicating with other complex SPI devices at speeds past their ratings, just to see what would happen. All started showing issues with modest increases, even when run at max Vdd. Yet I"m reading from this at 360% of its max rated speed! And I know of cases of others doing the same with their ILI9341-based LCD, as well.

This note will discuss the considerations made when choosing a microcontroller that will work for your display. A few requirements need to be met depending on the display’s features, interface, and size. These can also be determined by the embedded IC in the display. An overview of the considerations when choosing a microcontroller can be seen below. It should be noted that these items are separated for definition but may serve the same purpose and be interconnected in the ecosystem of the controller.

Application and display specific peripheral requirements. I2C, SPI, UART, Parallel, MIPI, LVDS, HDMI etc. Determines pin connections and required architecture of the device.

Flash and RAM memory requirements. Minimum frame buffer memory is dependent on the size andresolution of the display. Location of memory (external or internal) can restrict interface speed and must becompatible with the chosen interface.

Communication speed requirements defined by the interface and intended application. Refresh rateis determined on the size of the display and location of memory. This will indicate which processors arecompatible.

A displays embedded IC can offer resources such as internal RAM, clock generators and power control.This can save resources otherwise needed to be provided externally. Check the datasheet of the display’s ICcontroller for device function specifics.

Availability of resources for programming and debugging the microcontroller. Online resources andexampleprograms to leverage from can a lot of save time. Compatibility with a familiarprogramming environment isadditionally beneficial.

The interface selection is dependent on the intended application of the display. Each display has a different interface or different choices for a connection interface. For smaller displays a 3/4-wire serial interface would be sufficient. For larger display’s with high resolution a faster interface should be chosen. A parallel RGB interface is capable of high-speed data transmission however requires many pin connections. If the intended application for the display is video a MIPI, LVDS or HDMI connection would be a good choice.

The available memory of a microcontroller often becomes a highlighted issue when determining which microcontroller to select. The microcontroller needs a minimum amount of RAM to hold the frame buffer of the display. Even small displays require more RAM than a typical microcontroller possess. To verify that your microcontroller will have enough memory, it is important to calculate the frame buffer.

The minimum RAM required for the frame buffer in this example would then be 768kB. It is important to note that external RAM can be provided for the frame buffer if the microcontroller does not provide it internally. Clocking speed should be verified if using external RAM as the microcontroller cannot access external RAM as quickly. The clock frequency constrained by external RAM sometimes does not meet the minimum requirements of some very high-speed interfaces (ex. DSI-MIPI). Additionally, the display can contain some form of RAM depending on the IC controller inside the display. This can be verified on the specification sheet of the IC.

The speed of the microcontroller is heavily dependent on the interface used in the application. The minimum and maximum of the clock frequency is specified in the datasheet of the display and in the specification sheet of the display’s controller IC. The frame rate is typically around 50-60Hz, which is the median oscillation frequency to refresh the display to maintain an image. The display will often provide an internal high frequency clock that can be initialized to certain frequencies.

It is important to verify in the controller data sheet which resources are provided by the internal IC of the display. Some key information to look for would be: Does the display have sufficient RAM or does this need to be provided? Does the display have an internal oscillator for clock generation for the interface chosen? An additional graphics controller can be used to interface the display with the microcontroller to meet these requirements. Features like these can be utilized to avoid additional cost, space, and memory of your application.

After a brief consideration of intended application and interface of the display you can get some idea of which microcontroller processor and architecture you will need. There are a few different microcontroller processors to choose from. The main choices are ARM, AVR, PIC, and 8051. The difference between them is the bit size of the processor, 8-bit, 16-bit, 32-bit or 64-bit data . The data bit width is the amount of data that can be sent at a time. This determines the speed of data transfer and thus compatible applications and interfaces.

The AVR has an 8-bit processor and is a RISC type microcontroller. This type of processor is compatible with low speed interfaces (SPI, I2C) and smaller displays. A common AVR microcontroller board is the Arduino which has the embedded 8-bit ATMEL RISC processors. These processors are widely popular which provide the benefit of numerous online resources and availability. The Arduino processors (ATmega/SAM3X) are typically available in most microcontroller programming environments. Additionally, Arduino offers 32-bit AVR development boards which function closely to the ARM processors.

The AVR microcontrollers are constrained by the low frequency, internal memory availability and power costs. AVR’s cannot use external program memory but some may allow expansion of external SRAM. These microcontrollers alone would be incompatible for high frequency applications such as video, large displays, or capacitive touch panels.

The ARM microprocessors have a RISC architecture. They offer 32-bit or 64-bit processors and are great options for high speed interfaces (Parallel, LVDS, MIPI, HDMI) and high-resolution displays. Common ARM processors can be found from STMicroelectronics and Raspberry Pi. The most common version of the ARM processors is the “Microcontroller” Arm-M group which include the Cortex-M0 and Cortex-M4 series.

The ARM processors are compatible with most displays and connection interfaces. These microcontrollers have become increasingly popular, so the cost has become comparable between the ARM and the AVR types. These processors provide the speed, but it is recommended to verify the available RAM as these boards vary widely on included features.

The PIC architecture consists of 8, 16, and 32-bit processors developed by Microchip. The PIC 32-bit series of microcontrollers have been geared toward graphical embedded applications and there are a lot of resources online for these devices. There is a huge variety of PIC controllers which make them easily available. These microcontrollers are known for being low cost and are comparable to the ARM processors. The drawback of the PIC controllers is using Microchips programming environment, but this is based on preference.

The Intel MCS-51, more commonly known as the 8051 microcontrollers have a CISC architecture and an 8-bit processor. These processors differ in architecture from the previous and are programmed using a combination of C and assembly languages. The program memory is read only and does not have an on-board ISP. A special programming device is needed to rewrite the EEPROM or flash memory. These processors are typically small, low cost and low powered. This can make them favorable for battery powered devices. These processors are commonly used to initialize TFT displays and are combined with a graphics controller to provide the required resources such as RAM and clock frequency.

Development environments and online resources become considerably valuable when creating an application for your display. A brand new or uncommon microcontroller will have very few resources for reference. Even knowledgeable engineers can find frustrations with the manufacturers programming environments. There are many microcontroller choices that will support your display with similar and overlapping features. Choosing a microcontroller with an available FAQ, application notes or is accessible on a familiar programming platform can save a lot of time.

Buyers and others who are developing systems that incorporate FocusLCDs products (collectively, “Designers”) understand and agree that Designers remain responsible for using their independent analysis, evaluation and judgment in designing their applications and that Designers have full and exclusive responsibility to assure the safety of Designers" applications and compliance of their applications (and of all FocusLCDs products used in or for Designers’ applications) with all applicable regulations, laws and other applicable requirements.

Designer agrees that prior to using or distributing any applications that include FocusLCDs products, Designer will thoroughly test such applications and the functionality of such FocusLCDs products as used in such applications.

The maximum frequency of DCLK is the HFPERCLK/2 during the "porch" or non-visible area, and HFPERCLK/3 during the visible display area. In other words, two HFPERCLK cycles will be required to clock the DCLK once in the porch area, and three HFPERCLK cycles will be required when in the visible area. On parts with a 48 MHz system clock, this limitation results in a maximum of 24 MHz DCLK during the porch and 16 MHz DCLKduring the visible area.

Inactive EBI_DCLK edge is always at the beginning of the 1 cycle TFTSTART state; then there is always at least 1 cycle used in the RDSTRB phase; and finally the active EBI_DCLK edge is always in between TFTSETUP and TFTHOLD state (even if both are programmed to 0 cycles). In the scenario with TFTSTART is 1 cycle, RSSTRB is 1 cycle and 0 cycles for TFTSETUP and TFTHOLD, and one additional cycle is used as the minimum high/low time for EBI_DCLK.

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We will organize the kinds of display interfaces we offer, and how they differ. You will get to know what kind of external and internal interfaces we have and what are their main applications.

First, let us start with dividing internal and external interfaces in LCD modules. Internal interface of display means it used inside the device. Those are usually the embedded interfaces that are not visible, and we do not have access to them as the users of the device. External interfaces, on the other hand, are connected to the device using a cable. Once we have defined internal and external interfaces, both of these categories come as universal or image transfer interfaces.

A protocol defines the rules of information exchange, where the interface is the medium. The example here could be the language. When I use my voice to communicate with other people, my voice is an interface. Over this interface my voice is being sent to other people’s ears, and the protocol is the language used. Right now, I am using the English protocol. If you understand the protocol, you understand what I am saying. If I switch to a different language, Polish or some other language that you do not understand, you have the same interface, you will still hear me, but because of a different protocol, you do not understand me anymore. In this article we will talk only about interfaces, how to connect devices to each other. We will not focus on protocols.

Let’s try to get the interfaces right. For internal interfaces, interfaces embedded into the device, we have universal interfaces and image transfer interfaces. Universal display interface can send other data, not only an image. Being universal, they are not perfect for image transfer, because in most of the displays used nowadays, the image transfer is one of the most demanding. The bit rate, the data transfer needed for the image transfer is rather high. Higher that many universal interfaces can offer. If we need to send an image every once in a while, then we don’t need very high bandwidth. If we do not need live video stream, then we can use some of the internal universal interfaces such as SPI, I2C or even slow interfaces as RS232 or UART.

The first universal interface will be SPI (Serial Peripheral Interface). This interface is serial, used for communication between a host, in SPI called a Master, and devices called Slaves. One host can communicate with many slaves. To select the Slave, we use the Chip select or SS line and then we use two data lines, Master output or Master input. And of course we have to define the clock, to synchronize the data, because this is a clock synchronized interface.

It can be fast but is not fast enough for live video. The baud rate can be 1 MBd, but it can also be 10 MBd or even 50 MBd on the SPI or QSPI. QSPI is a Quad SPI, a kind of modification of SPI that is faster. But still this interface is very universal, we can use it to connect memory or some input and outputs internally in our device. In the display universe the SPI is used for simple displays, for small size displays, where we can transfer the image relatively fast, because the resolution is low. The maximum size for SPI display interface would be 3.5 inch, 320 by 240 pixel TFT displays. If we have higher resolution, image transfer will be too slow to use SPI even with a high-speed SPI.

Next, we have the I2C interface. This kind of interface is usually slower than SPI. It uses only two lines, so one is a clock for synchronization, and the other one is the data line. This data line is bidirectional. It means that if in SPI we have two data lines, one outgoing and one incoming, then in an I2C interface we have only one data line.

If, for example, the Master is sending some data, the only thing Slaves can do is to receive it. And then we need to wait a little bit for the Master to finish. We can then respond as Slave to Master. In I2C Slave selection works a little bit different than in SPI, where  we had a Chip Select line (CS line) or SS line to select from. In I2C we first need to send the logical address to the interface that is being written by Slaves. In general, this procedure is slow and universal interface used also to connect the simple memory and some other I2S that we have around our microcontroller on the PCB. It is very useful, but usually not used for image transfer. This interface is very popular in the display world for touchscreens. Most of the embedded touch screens that we use have I2C interface because the touchscreen does not generate many data. We only have coordinates of the finger or few fingers at most, that need to be sent back to the microcontroller, to the device processor. The slow baud rate is good enough for the touchscreen, but not enough for the image.

The UART is basically the same as RS232, but it is a fully internal interface. It is pretty slow. We have a TX line and a RX line – a Transmit Line and a Receive Line. We do not have a clock here, we only have a clock to synchronize the device internally, but the clock signal is not sent out. So, we need to synchronize the data that is coming through the lines and to do that we need to set the same baud rate on both sides of the communication line. That means that before we use UART we need to agree first what speed we will use.

That is not a case for SPI or I2C, because we have a clock there that gives the speed to every device. Then each device works according to the clock. In UART we do not have a clock. It is rather not used for image transfer. The UART, or SPI, or I2C can be used for low resolution displays. For high resolution displays we need an Intelligent Display, a display that will generate the image internally and through these slow universal interfaces we only send commands, or we send the image once, the image is being stored into the internal memory of the intelligent display, that we will use later sending the commands. You can find Riverdi’s intelligent display line on our website: https://riverdi.com/product-category/intelligent-displays/.

These Riverdi products are very advanced Intelligent Displays, made with Bridgetek controllers. The controllers use SPI and QSPI for communication. That means your software, your system, your microcontroller can be simple. You can use SPI interface to drive them, and you can still have high resolution image, even as high as 1280 by 800 pixels in 10.1-inch LCD displays. So, please remember that if you want to use a slow universal interface and have a high-resolution image, you need to use an Intelligent Display.

There are also the internal image transfer interfaces. The image transfer interface allows continuous high speed image transfer. Internal transfer is high enough to refresh the display many times per second. This is called the refresh rate of a display. When you go to a display, monitor, or TV set specification, you will see  refresh rate or maximum refresh rate parameter. If it’s 60 Hertz, that means the display image is refreshed 60 times per second. More advanced displays would have higher values, like 100 Hertz. The refresh rate means we need to send full image 60 times or 100 times in each second. To visualize this amount of data, we need to multiply refresh rate by the resolution of the screen. For example, for a 7-inch Riverdi LVDS display with resolution 1024 by 600 it is roughly 600 thousand pixels.

The most common internal image transfer interface in industrial LCD displays nowadays is LVDS – Low Voltage Differential Signal. A crucial feature of this interface is that it is differential. It means that the signal is immune to interference and we can use a twisted pair of wires to transfer the data. We can send data fast and it will not be corrupt by any noise, interference. This kind of data corruption is quite common in other interfaces.

The next, older image transfer interface is called RGB. Name comes from the colors sent parallelly to the display: red, green and blue. LVDS is a serial interface and the RGB is a parallel interface. The main difference is that RGB is not differential, so it is easier to disturb signal with noise and you configure the speed of this interface too high. Parallel interface means that we send every bit in a separate line. In theory this interface could be fast, but because it is not differential, the transfer speed is limited. Moreover, the RGB display interface will work with rather small screen sizes –  usually up to 7-inch or 10-inch.

12 inch screen size is the total maximum for a LCD display with RGB interface, but the resolution will be lower, like 800 by 600. For this display size it is very low resolution. This is the reason why the 7-inch is size above which the LCD displays are being switched from RGB to LVDS interface. Among Riverdi products (if you go to the Riverdi website and to the IPS display tab), there are displays without the controller, and the small displays like 3.5-inch, 4.3-inch and 5-inch are equipped with RGB interface. But when you go to the 7-inch LCD displays tab on Riverdi website, you will find RGB, LVDS and MIPI displays. But when you go to the 10-inch or bigger displays, you will only find the LVDS displays because our 10-inch LCD displays are high resolution 1280 by 800, and it is impossible to build it with the RGB interface.

MIPI – Mobile Industry Processor Interface – is an internally embedded image transfer interface, getting popular these days. This kind of interface is used in mobile applications, tablets or mobile phones, but it is entering as an option in industrial applications. In Riverdi we offer 7-inch MIPI displays, but please be careful with other MIPI displays on the market. Many come from mobile phones or tablet market. Also, the TFT glass availability may not be stable as the mobile market changes really fast, every six months or every year. When you buy a 7-inch Riverdi MIPI interface display you are safe, because it is an industrial display.

This is why we have a limited number of displays with MIPI interface – we want to be sure that what we sale will be available for a long time. Longevity is one of Riverdi’s core values and we do not want to deliver anything that will not be supported for a minimum 3 to 5 years. It is because many of our customers are making industrial, medical or military devices and they need displays to be available long-term.

Next interface is the Vx1. It is similar to LVDS  and MIPI, so it’s low voltage differential signal. Vx1 is a very high-speed interface, usually used in large high-resolution screens, like 55-inch 4K TVs or even larger ones. If you buy this kind of a TV set right now, probably the embedded interface inside will be the Vx1.

Key takeaway: Vx1 is a super-fast interface used for high bandwidth image transfer, with high refresh rate and high-resolution displays, used in 4K screens and above.

The last internal image transfer interface is Embedded DisplayPort (eDP). We call it the new LVDS, because many new industrial displays are equipped with the eDP. If you go through industrial manufacturers of TFT LCD displays, you will notice increasing number of models available with the eDP. eDP is also a native interface in new Intel or AMD based processors.

Key Takeaway: With the embedded DisplayPort as a native display interface you can cut down costs, because you do not need anything extra to connect a display to the processor.

Now, with the processors on the market, we need displays with embedded DisplayPort. Many laptops or monitors already use embedded DisplayPort as an internal interface instead of LVDS. LVDS still is the most popular industrial LCD display interface. All the internal image transfer interfaces like MIPI, Vx1 and eDP are variations of LVDS, where the protocols and the signals are a little bit different. For example, for eDP we can have lower noise and reduced power consumption. All of them have advantages over regular LVDS, but they are all LVDS type.

Now, let’s take a closer look at external interfaces. Those are the ones that we usually have direct access to. It can be TV or monitor connected to your computer with the HDMI . It can be a DVI usually used for monitors. Or VGA which is an outdated image interface for monitors.  The DisplayPort that is a HDMI successor. Finally, an universal USB-C, the most common interface nowadays used to connect devices.

USB-C transmits up to 100 watt of power, because you can increase voltage and current. In a regular USB it is usually 5 volt and 0.5 or 1.0 amp, so only a couple watts. In USB-C you increase the voltage up to 20 volt and with the 5 amp current, so in total it’s even 100 watt of power.  This interface is made not only for data, but for real power transfer. Through USB-C you can charge your phone and your laptop. If you buy a new laptop right now, you may even not get a regular power connector, but only an USB-C. The USB-C is a very smart interface. If you connect the devices, they can negotiate with each other which one has more power. For example, if we connect a charger to a laptop, the charger has more power and will charge the laptop, but if you connect the laptop with the same interface to your mobile phone, then they will discuss the power levels, and of course the laptop will be charging the phone. You can already find monitors on the market that have USB-C instead of HDMI. Those monitors can be powered from your computer and need only one USB cable, both for image transfer and power.  For sure the future belongs to USB-C implementations.

Let’s move on to image transfer interfaces. The most common one is HDMI – High-Definition Multimedia Interface. M stands for Multimedia, because it transfers image with sound. If you connect your computer to your TV set with HDMI, you will need one cable for both the video and the audio. There are variations of HDMI connectors:

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The next one is DVI – Digital Visual Interface. The first DVI was not a multimedia interface, because it did not have audio data transfer. Nowadays, there are some variations that can transfer audio, but it is non-standard. We can assume DVI is rather for image transfer. It is a digital interface, similar in signals to HDMI. The latest variation is DVI-I, where I stands for integrated interface. It can have a digital and analog part for VGA compatibility. In the picture above there is a DVI-D, digital only, where we do not have the pins for analog VGA interface. Analog VGA is sometimes available in your desktop computer, but not in laptops anymore.

The oldest video interface still in use  is the VGA – Video Graphic Array interface. It becomes less and less popular. This is an analog interface, not a digital one like all the other abovementioned interfaces. Analog interface means that we do not transmit the bits, but we send the voltages values. The analog signals are not stable, they are quite easy to disturb, so the transfer cannot be very high in speed and volume

The last external interface that we can find in our devices nowadays is a DisplayPort. DisplayPort is similar to HDMI or DVI. It can also transfer image and sound. It is even faster than the HDMI. Usually, the DisplayPort is used for high resolution displays, for new monitors and TVs with 4K or 8K resolution where it is really hard, or nearly impossible, to achieve such resolution using HDMI interface.

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This is SainSmart MEGA2560  + 7 inch TFT LCD module with the TFT LCD shield kit For arduino enthusiasts.It includes one pcs of SainSmart MEGA2560 , 7 inch TFT LCD display and a TFT LCD shield for Arduino MEGA2560.This kit helps you to avoid complicated wiring processes and save you much time to accomplish your goal. You can feel free to enjoy the touch function and SD card function by using our codes.We will provided you the whole document including the example project of the kit. We will supply you the technical support after your purchase.

It is 100% compatible with the normal MCU like ARM AVR PIC and 8051,especially on Arduino family such as Arduino Due and Arduino MEGA2560(R3). The module uses the LCD controller Chip SSD1963 with 7 inch LCD including the touchscreen.

LCD-specificed intialization code is provided, so that you can save time to optimize power control register and gamma curves for best display performance. We have test the provided code, it gives the best display performanace

This is Sainsmart TFT LCD Extend shield for arduino due .Using this shield can help you out of the bothers to use other cables. You just need to plug the module to arduino due through this shield.

The shield defines that all the the data transmit ports are PC1-PC8 and PC12-PC19,the controll pins are PD0-PD3.The perfect design could realize that the data transmits in high speed.The SPI interface is designed in the ISP header of arduino due so that the SPI transfer with DMA could be achieved in high speed with no drag.

This shiled is just for Arduno MEGA2560. If you need the LCD Extend shield for Arduino Due,you need a similar shield which is also provided from our store.

This shiled is just for 7 inch TFT LCD.If you need the LCD Extend shield for 3.2/3.5/...,you need a similar shield which is also provided from our store.

I will use a 3.3v 500mA power supply connected to a lipo battery, probably with or maybe without a over discharge circuit. The power supply MIC5219-3.3V have a ENable pin, so if I utilize it, I can get less than 5 micro amps of current draw, which is certainly an overkill, if I use the power on/off thing that cut off 3.3v on the teensy, I can get less than 200 micro amps. I wonder if I can hook a GPIO pin to the power on/off pin, so I can pull it to high or low for a few seconds to turn if off, and also a physical button is connected to the power on/off so I can power it on with one click and hold button to force shutdown.

The linear power supply is [+]Efficient and [+]Small but [-]Can"t output 5v [-]Low max current output [-]Have 500mV dropout voltage @500mA so the battery is unusable when it is 3.7 volts, which is real bad as lithium batteries" protector boards over discharge kicks in @2.4v. I also need 5v for the USB host port for keyboards and mouse. Because the host port is not needed at all times, so I wanted to use existing power bank circuit that auto turns on when peripherals are connected. (Existing circuits are great, maybe efficient and safer), so no boosting required if not needed.

Using the power bank circuit that my li polymer battery comes with (power bank comes with) can [+]output more current, so can also power keyboard mice and hubs. [+]safe, with protection [+]only powers on when there is current draw (Teensy itself may not be able to keep it on, maybe can with the LCD backlight) or/and USB device is connected. Some people add resisters to add current draw, and that is bullshit. Another problem is how to control whether I want the converter to start or not, and have no complete control sucks.

Glass substrate with ITO electrodes. The shapes of these electrodes will determine the shapes that will appear when the LCD is switched ON. Vertical ridges etched on the surface are smooth.

A liquid-crystal display (LCD) is a flat-panel display or other electronically modulated optical device that uses the light-modulating properties of liquid crystals combined with polarizers. Liquid crystals do not emit light directlybacklight or reflector to produce images in color or monochrome.seven-segment displays, as in a digital clock, are all good examples of devices with these displays. They use the same basic technology, except that arbitrary images are made from a matrix of small pixels, while other displays have larger elements. LCDs can either be normally on (positive) or off (negative), depending on the polarizer arrangement. For example, a character positive LCD with a backlight will have black lettering on a background that is the color of the backlight, and a character negative LCD will have a black background with the letters being of the same color as the backlight. Optical filters are added to white on blue LCDs to give them their characteristic appearance.

LCDs are used in a wide range of applications, including LCD televisions, computer monitors, instrument panels, aircraft cockpit displays, and indoor and outdoor signage. Small LCD screens are common in LCD projectors and portable consumer devices such as digital cameras, watches, calculators, and mobile telephones, including smartphones. LCD screens have replaced heavy, bulky and less energy-efficient cathode-ray tube (CRT) displays in nearly all applications. The phosphors used in CRTs make them vulnerable to image burn-in when a static image is displayed on a screen for a long time, e.g., the table frame for an airline flight schedule on an indoor sign. LCDs do not have this weakness, but are still susceptible to image persistence.

Each pixel of an LCD typically consists of a layer of molecules aligned between two transparent electrodes, often made of Indium-Tin oxide (ITO) and two polarizing filters (parallel and perpendicular polarizers), the axes of transmission of which are (in most of the cases) perpendicular to each other. Without the liquid crystal between the polarizing filters, light passing through the first filter would be blocked by the second (crossed) polarizer. Before an electric field is applied, the orientation of the liquid-crystal molecules is determined by the alignment at the surfaces of electrodes. In a twisted nematic (TN) device, the surface alignment directions at the two electrodes are perpendicular to each other, and so the molecules arrange themselves in a helical structure, or twist. This induces the rotation of the polarization of the incident light, and the device appears gray. If the applied voltage is large enough, the liquid crystal molecules in the center of the layer are almost completely untwisted and the polarization of the incident light is not rotated as it passes through the liquid crystal layer. This light will then be mainly polarized perpendicular to the second filter, and thus be blocked and the pixel will appear black. By controlling the voltage applied across the liquid crystal layer in each pixel, light can be allowed to pass through in varying amounts thus constituting different levels of gray.

The chemical formula of the liquid crystals used in LCDs may vary. Formulas may be patented.Sharp Corporation. The patent that covered that specific mixture expired.

Most color LCD systems use the same technique, with color filters used to generate red, green, and blue subpixels. The LCD color filters are made with a photolithography process on large glass sheets that are later glued with other glass sheets containing a TFT array, spacers and liquid crystal, creating several color LCDs that are then cut from one another and laminated with polarizer sheets. Red, green, blue and black photoresists (resists) are used. All resists contain a finely ground powdered pigment, with particles being just 40 nanometers across. The black resist is the first to be applied; this will create a black grid (known in the industry as a black matrix) that will separate red, green and blue subpixels from one another, increasing contrast ratios and preventing light from leaking from one subpixel onto other surrounding subpixels.Super-twisted nematic LCD, where the variable twist between tighter-spaced plates causes a varying double refraction birefringence, thus changing the hue.

LCD in a Texas Instruments calculator with top polarizer removed from device and placed on top, such that the top and bottom polarizers are perpendicular. As a result, the colors are inverted.

The optical effect of a TN device in the voltage-on state is far less dependent on variations in the device thickness than that in the voltage-off state. Because of this, TN displays with low information content and no backlighting are usually operated between crossed polarizers such that they appear bright with no voltage (the eye is much more sensitive to variations in the dark state than the bright state). As most of 2010-era LCDs are used in television sets, monitors and smartphones, they have high-resolution matrix arrays of pixels to display arbitrary images using backlighting with a dark background. When no image is displayed, different arrangements are used. For this purpose, TN LCDs are operated between parallel polarizers, whereas IPS LCDs feature crossed polarizers. In many applications IPS LCDs have replaced TN LCDs, particularly in smartphones. Both the liquid crystal material and the alignment layer material contain ionic compounds. If an electric field of one particular polarity is applied for a long period of time, this ionic material is attracted to the surfaces and degrades the device performance. This is avoided either by applying an alternating current or by reversing the polarity of the electric field as the device is addressed (the response of the liquid crystal layer is identical, regardless of the polarity of the applied field).

Displays for a small number of individual digits or fixed symbols (as in digital watches and pocket calculators) can be implemented with independent electrodes for each segment.alphanumeric or variable graphics displays are usually implemented with pixels arranged as a matrix consisting of electrically connected rows on one side of the LC layer and columns on the other side, which makes it possible to address each pixel at the intersections. The general method of matrix addressing consists of sequentially addressing one side of the matrix, for example by selecting the rows one-by-one and applying the picture information on the other side at the columns row-by-row. For details on the various matrix addressing schemes see passive-matrix and active-matrix addressed LCDs.

LCDs are manufactured in cleanrooms borrowing techniques from semiconductor manufacturing and using large sheets of glass whose size has increased over time. Several displays are manufactured at the same time, and then cut from the sheet of glass, also known as the mother glass or LCD glass substrate. The increase in size allows more displays or larger displays to be made, just like with increasing wafer sizes in semiconductor manufacturing. The glass sizes are as follows:

Until Gen 8, manufacturers would not agree on a single mother glass size and as a result, different manufacturers would use slightly different glass sizes for the same generation. Some manufacturers have adopted Gen 8.6 mother glass sheets which are only slightly larger than Gen 8.5, allowing for more 50 and 58 inch LCDs to be made per mother glass, specially 58 inch LCDs, in which case 6 can be produced on a Gen 8.6 mother glass vs only 3 on a Gen 8.5 mother glass, significantly reducing waste.AGC Inc., Corning Inc., and Nippon Electric Glass.

The origins and the complex history of liquid-crystal displays from the perspective of an insider during the early days were described by Joseph A. Castellano in Liquid Gold: The Story of Liquid Crystal Displays and the Creation of an Industry.IEEE History Center.Peter J. Wild, can be found at the Engineering and Technology History Wiki.

In 1922, Georges Friedel described the structure and properties of liquid crystals and classified them in three types (nematics, smectics and cholesterics). In 1927, Vsevolod Frederiks devised the electrically switched light valve, called the Fréedericksz transition, the essential effect of all LCD technology. In 1936, the Marconi Wireless Telegraph company patented the first practical application of the technology, "The Liquid Crystal Light Valve". In 1962, the first major English language publication Molecular Structure and Properties of Liquid Crystals was published by Dr. George W. Gray.RCA found that liquid crystals had some interesting electro-optic characteristics and he realized an electro-optical effect by generating stripe-patterns in a thin layer of liquid crystal material by the application of a voltage. This effect is based on an electro-hydrodynamic instability forming what are now called "Williams domains" inside the liquid crystal.

In 1964, George H. Heilmeier, then working at the RCA laboratories on the effect discovered by Williams achieved the switching of colors by field-induced realignment of dichroic dyes in a homeotropically oriented liquid crystal. Practical problems with this new electro-optical effect made Heilmeier continue to work on scattering effects in liquid crystals and finally the achievement of the first operational liquid-crystal display based on what he called the George H. Heilmeier was inducted in the National Inventors Hall of FameIEEE Milestone.

In the late 1960s, pioneering work on liquid crystals was undertaken by the UK"s Royal Radar Establishment at Malvern, England. The team at RRE supported ongoing work by George William Gray and his team at the University of Hull who ultimately discovered the cyanobiphenyl liquid crystals, which had correct stability and temperature properties for application in LCDs.

The idea of a TFT-based liquid-crystal display (LCD) was conceived by Bernard Lechner of RCA Laboratories in 1968.dynamic scattering mode (DSM) LCD that used standard discrete MOSFETs.

On December 4, 1970, the twisted nematic field effect (TN) in liquid crystals was filed for patent by Hoffmann-LaRoche in Switzerland, (Swiss patent No. 532 261) with Wolfgang Helfrich and Martin Schadt (then working for the Central Research Laboratories) listed as inventors.Brown, Boveri & Cie, its joint venture partner at that time, which produced TN displays for wristwatches and other applications during the 1970s for the international markets including the Japanese electronics industry, which soon produced the first digital quartz wristwatches with TN-LCDs and numerous other products. James Fergason, while working with Sardari Arora and Alfred Saupe at Kent State University Liquid Crystal Institute, filed an identical patent in the United States on April 22, 1971.ILIXCO (now LXD Incorporated), produced LCDs based on the TN-effect, which soon superseded the poor-quality DSM types due to improvements of lower operating voltages and lower power consumption. Tetsuro Hama and Izuhiko Nishimura of Seiko received a US patent dated February 1971, for an electronic wristwatch incorporating a TN-LCD.

In 1972, the concept of the active-matrix thin-film transistor (TFT) liquid-crystal display panel was prototyped in the United States by T. Peter Brody"s team at Westinghouse, in Pittsburgh, Pennsylvania.Westinghouse Research Laboratories demonstrated the first thin-film-transistor liquid-crystal display (TFT LCD).high-resolution and high-quality electronic visual display devices use TFT-based active matrix displays.active-matrix liquid-crystal display (AM LCD) in 1974, and then Brody coined the term "active matrix" in 1975.

In 1972 North American Rockwell Microelectronics Corp introduced the use of DSM LCDs for calculators for marketing by Lloyds Electronics Inc, though these required an internal light source for illumination.Sharp Corporation followed with DSM LCDs for pocket-sized calculators in 1973Seiko and its first 6-digit TN-LCD quartz wristwatch, and Casio"s "Casiotron". Color LCDs based on Guest-Host interaction were invented by a team at RCA in 1968.TFT LCDs similar to the prototypes developed by a Westinghouse team in 1972 were patented in 1976 by a team at Sharp consisting of Fumiaki Funada, Masataka Matsuura, and Tomio Wada,

In 1983, researchers at Brown, Boveri & Cie (BBC) Research Center, Switzerland, invented the passive matrix-addressed LCDs. H. Amstutz et al. were listed as inventors in the corresponding patent applications filed in Switzerland on July 7, 1983, and October 28, 1983. Patents were granted in Switzerland CH 665491, Europe EP 0131216,

The first color LCD televisions were developed as handheld televisions in Japan. In 1980, Hattori Seiko"s R&D group began development on color LCD pocket televisions.Seiko Epson released the first LCD television, the Epson TV Watch, a wristwatch equipped with a small active-matrix LCD television.dot matrix TN-LCD in 1983.Citizen Watch,TFT LCD.computer monitors and LCD televisions.3LCD projection technology in the 1980s, and licensed it for use in projectors in 1988.compact, full-color LCD projector.

In 1990, under different titles, inventors conceived electro optical effects as alternatives to twisted nematic field effect LCDs (TN- and STN- LCDs). One approach was to use interdigital electrodes on one glass substrate only to produce an electric field essentially parallel to the glass substrates.Germany by Guenter Baur et al. and patented in various countries.Hitachi work out various practical details of the IPS technology to interconnect the thin-film transistor array as a matrix and to avoid undesirable stray fields in between pixels.

Hitachi also improved the viewing angle dependence further by optimizing the shape of the electrodes (Super IPS). NEC and Hitachi become early manufacturers of active-matrix addressed LCDs based on the IPS technology. This is a milestone for implementing large-screen LCDs having acceptable visual performance for flat-panel computer monitors and television screens. In 1996, Samsung developed the optical patterning technique that enables multi-domain LCD. Multi-domain and In Plane Switching subsequently remain the dominant LCD designs through 2006.South Korea and Taiwan,

In 2007 the image quality of LCD televisions surpassed the image quality of cathode-ray-tube-based (CRT) TVs.LCD TVs were projected to account 50% of the 200 million TVs to be shipped globally in 2006, according to Displaybank.Toshiba announced 2560 × 1600 pixels on a 6.1-inch (155 mm) LCD panel, suitable for use in a tablet computer,

In 2016, Panasonic developed IPS LCDs with a contrast ratio of 1,000,000:1, rivaling OLEDs. This technology was later put into mass production as dual layer, dual panel or LMCL (Light Modulating Cell Layer) LCDs. The technology uses 2 liquid crystal layers instead of one, and may be used along with a mini-LED backlight and quantum dot sheets.

Since LCDs produce no light of their own, they require external light to produce a visible image.backlight. Active-matrix LCDs are almost always backlit.Transflective LCDs combine the features of a backlit transmissive display and a reflective display.

CCFL: The LCD panel is lit either by two cold cathode fluorescent lamps placed at opposite edges of the display or an array of parallel CCFLs behind larger displays. A diffuser (made of PMMA acrylic plastic, also known as a wave or light guide/guiding plateinverter to convert whatever DC voltage the device uses (usually 5 or 12 V) to ≈1000 V needed to light a CCFL.

EL-WLED: The LCD panel is lit by a row of white LEDs placed at one or more edges of the screen. A light diffuser (light guide plate, LGP) is then used to spread the light evenly across the whole display, similarly to edge-lit CCFL LCD backlights. The diffuser is made out of either PMMA plastic or special glass, PMMA is used in most cases because it is rugged, while special glass is used when the thickness of the LCD is of primary concern, because it doesn"t expand as much when heated or exposed to moisture, which allows LCDs to be just 5mm thick. Quantum dots may be placed on top of the diffuser as a quantum dot enhancement film (QDEF, in which case they need a layer to be protected from heat and humidity) or on the color filter of the LCD, replacing the resists that are normally used.

WLED array: The LCD panel is lit by a full array of white LEDs placed behind a diffuser behind the panel. LCDs that use this implementation will usually have the ability to dim or completely turn off the LEDs in the dark areas of the image being displayed, effectively increasing the contrast ratio of the display. The precision with which this can be done will depend on the number of dimming zones of the display. The more dimming zones, the more precise the dimming, with less obvious blooming artifacts which are visible as dark grey patches surrounded by the unlit areas of the LCD. As of 2012, this design gets most of its use from upscale, larger-screen LCD televisions.

RGB-LED array: Similar to the WLED array, except the panel is lit by a full array of RGB LEDs. While displays lit with white LEDs usually have a poorer color gamut than CCFL lit displays, panels lit with RGB LEDs have very wide color gamuts. This implementation is most popular on professional graphics editing LCDs. As of 2012, LCDs in this category usually cost more than $1000. As of 2016 the cost of this category has drastically reduced and such LCD televisions obtained same price levels as the former 28" (71 cm) CRT based categories.

Monochrome LEDs: such as red, green, yellow or blue LEDs are used in the small passive monochrome LCDs typically used in clocks, watches and small appliances.

Today, most LCD screens are being designed with an LED backlight instead of the traditional CCFL backlight, while that backlight is dynamically controlled with the video information (dynamic backlight control). The combination with the dynamic backlight control, invented by Philips researchers Douglas Stanton, Martinus Stroomer and Adrianus de Vaan, simultaneously increases the dynamic range of the display system (also marketed as HDR, high dynamic range television or FLAD, full-area local area dimming).

The LCD backlight systems are made highly efficient by applying optical films such as prismatic structure (prism sheet) to gain the light into the desired viewer directions and reflective polarizing films that recycle the polarized light that was formerly absorbed by the first polarizer of the LCD (invented by Philips researchers Adrianus de Vaan and Paulus Schaareman),

A pink elastomeric connector mating an LCD panel to circuit board traces, shown next to a centimeter-scale ruler. The conductive and insulating layers in the black stripe are very small.

A standard television receiver screen, a modern LCD panel, has over six million pixels, and they are all individually powered by a wire network embedded in the screen. The fine wires, or pathways, form a grid with vertical wires across the whole screen on one side of the screen and horizontal wires across the whole screen on the other side of the screen. To this grid each pixel has a positive connection on one side and a negative connection on the other side. So the total amount of wires needed for a 1080p display is 3 x 1920 going vertically and 1080 going horizontally for a total of 6840 wires horizontally and vertically. That"s three for red, green and blue and 1920 columns of pixels for each color for a total of 5760 wires going vertically and 1080 rows of wires going horizontally. For a panel that is 28.8 inches (73 centimeters) wide, that means a wire density of 200 wires per inch along the horizontal edge.

The LCD panel is powered by LCD drivers that are carefully matched up with the edge of the LCD panel at the factory level. The drivers may be installed using several methods, the most common of which are COG (Chip-On-Glass) and TAB (Tape-automated bonding) These same principles apply also for smartphone screens that are much smaller than TV screens.anisotropic conductive film or, for lower densities, elastomeric connectors.

Monochrome and later color passive-matrix LCDs were standard in most early laptops (although a few used plasma displaysGame Boyactive-matrix became standard on all laptops. The commercially unsuccessful Macintosh Portable (released in 1989) was one of the first to use an active-matrix display (though still monochrome). Passive-matrix LCDs are still used in the 2010s for applications less demanding than laptop computers and TVs, such as inexpensive calculators. In particular, these are used on portable devices where less information content needs to be displayed, lowest power consumption (no backlight) and low cost are desired or readability in direct sunlight is needed.

A comparison between a blank passive-matrix display (top) and a blank active-matrix display (bottom). A passive-matrix display can be identified when the blank background is more grey in appearance than the crisper active-matrix display, fog appears on all edges of the screen, and while pictures appear to be fading on the screen.

Displays having a passive-matrix structure are employing Crosstalk between activated and non-activated pixels has to be handled properly by keeping the RMS voltage of non-activated pixels below the threshold voltage as discovered by Peter J. Wild in 1972,

STN LCDs have to be continuously refreshed by alternating pulsed voltages of one polarity during one frame and pulses of opposite polarity during the next frame. Individual pixels are addressed by the corresponding row and column circuits. This type of display is called response times and poor contrast are typical of passive-matrix addressed LCDs with too many pixels and driven according to the "Alt & Pleshko" drive scheme. Welzen and de Vaan also invented a non RMS drive scheme enabling to drive STN displays with video rates and enabling to show smooth moving video images on an STN display.

Bistable LCDs do not require continuous refreshing. Rewriting is only required for picture information changes. In 1984 HA van Sprang and AJSM de Vaan invented an STN type display that could be operated in a bistable mode, enabling extremely high resolution images up to 4000 lines or more using only low voltages.

High-resolution color displays, such as modern LCD computer monitors and televisions, use an active-matrix structure. A matrix of thin-film transistors (TFTs) is added to the electrodes in contact with the LC layer. Each pixel has its own dedicated transistor, allowing each column line to access one pixel. When a row line is selected, all of the column lines are connected to a row of pixels and voltages corresponding to the picture information are driven onto all of the column lines. The row line is then deactivated and the next row line is selected. All of the row lines are selected in sequence during a refresh operation. Active-matrix addressed displays look brighter and sharper than passive-matrix addressed displays of the same size, and generally have quicker response times, producing much better images. Sharp produces bistable reflective LCDs with a 1-bit SRAM cell per pixel that only requires small amounts of power to maintain an image.

Segment LCDs can also have color by using Field Sequential Color (FSC LCD). This kind of displays have a high speed passive segment LCD panel with an RGB backlight. The backlight quickly changes color, making it appear white to the naked eye. The LCD panel is synchronized with the backlight. For example, to make a segment appear red, the segment is only turned ON when the backlight is red, and to make a segment appear magenta, the segment is turned ON when the backlight is blue, and it continues to be ON while the backlight becomes red, and it turns OFF when the backlight becomes green. To make a segment appear black, the segment is always turned ON. An FSC LCD divides a color image into 3 images (one Red, one Green and one Blue) and it displays them in order. Due to persistence of vision, the 3 monochromatic images appear as one color image. An FSC LCD needs an LCD panel with a refresh rate of 180 Hz, and the response time is reduced to just 5 milliseconds when compared with normal STN LCD panels which have a response time of 16 milliseconds.

Samsung introduced UFB (Ultra Fine & Bright) displays back in 2002, utilized the super-birefringent effect. It has the luminance, color gamut, and most of the contrast of a TFT-LCD, but only consumes as much power as an STN display, according to Samsung. It was being used in a variety of Samsung cellular-telephone models produced until late 2006, when Samsung stopped producing UFB displays. UFB displays were also used in certain models of LG mobile phones.

Twisted nematic displays contain liquid crystals that twist and untwist at varying degrees to allow light to pass through. When no voltage is applied to a TN liquid crystal cell, polarized light passes through the 90-degrees twisted LC layer. In proportion to the voltage applied, the liquid crystals untwist changing the polarization and blocking the light"s path. By properly adjusting the level of the voltage almost any gray level or transmission can be achieved.

In-plane switching is an LCD technology that aligns the liquid crystals in a plane parallel to the glass substrates. In this method, the electrical field is applied through opposite electrodes on the same glass substrate, so that the liquid crystals can be reoriented (switched) essentially in the same plane, although fringe fields inhibit a homogeneous reorientation. This requires two transistors for each pixel instead of the single transistor needed for a standard thin-film transistor (TFT) display. The IPS technology is used in everything from televisions, computer monitors, and even wearable devices, especially almost all LCD smartphone panels are IPS/FFS mode. IPS displays belong to the LCD panel family screen types. The other two types are VA and TN. Before LG Enhanced IPS was introduced in 2001 by Hitachi as 17" monitor in Market, the additional transistors resulted in blocking more transmission area, thus requiring a brighter backlight and consuming more power, making this type of display less desirable for notebook computers. Panasonic Himeji G8.5 was using an enhanced version of IPS, also LGD in Korea, then currently the world biggest LCD panel manufacture BOE in China is also IP