点阵LED外文翻译3000字文献教学内容

Based on AT89C52 LED overview

LED (Light Emitting Diode), light-emitting diode, is a solid state semiconductor devices, which can be directly converted into electricity to light. LED is the heart of a semiconductor chip, the chip is attached to one end of a stent, is the negative side, the other end of the power of the cathode, the entire chip package to be epoxy resin. Semiconductor chip is composed of two parts, part of the P-type semiconductor, it inside the hole-dominated, the other side is the N-type semiconductor, here is mainly electronic. But linking the two semiconductors, among them the formation of a "PN junction." When the current through the wires role in this chip, will be pushing e-P, P zone in the hole with electronic composite, and then to be issued in the form of photon energy, and this is the principle of LED luminescence. The wavelength of light that is the color of light, is formed by the PN junction of the decisions of the material.

LED history 50 years ago, people have to understand semiconductor materials can produce light of the basic knowledge, the first commercial diodes in 1960. English is the LED light emitting diode (LED) acronym, and its basic structure is an electroluminescent semiconductor materials, placed in a wire rack, then sealed with epoxy resin around, that is, solid package, Therefore, the protection of the internal batteries can play the role of line, so the seismic performance LED good.

LED is the core of the P-type semiconductor and components of the N-type semiconductor chips, the P-type semiconductor and N-type semiconductor between a transition layer, called the PN junction. In some semiconductor materials in the PN junction, the injection of a small number of carrier-carrier and the majority of the extra time will be in the form of light energy to release, thus the power to direct conversion of solar energy. PN junction on reverse voltage, a few hard-carrier injection, it is not luminous. This use of injection electroluminescent diodes is produced by the principle of light-emitting diodes, commonly known as LED. When it in a positive state of the work (that is, at both ends with forward voltage), the current flows from the LED anode, cathode, semiconductor crystals on the issue from the ultraviolet to infrared light of different colors, light and the strength of the currents.

Instruments used for the first LED light source instructions, but all kinds of light colored LED lights in traffic and large screen has been widely applied, have a very good economic and social benefits. The 12-inch red traffic lights as an example, is used in the United States have long life, low-efficiency 140 watt incandescent lamp as a light source, it produced 2,000 lumens of white light. The red filter, the loss-90 percent, only 200 lumens of red light. In the light of the new design, Lumileds companies have 18 red LED light source, including the loss of circuit, a total power consumption of 14 watts to generate the same optical effect. Automotive LED lights is also the source of important areas.

For general lighting, people need more white light sources. The 1998 white LED successful development. This is the GaN LED chip and Yttrium Aluminum Garnet (YAG) package together cause. GaN chip of the Blu-ray (λ p = 465nm, Wd = 30nm), made of high-temperature sintering of the Ce3 + YAG phosphors excited by this Blu-ray after irradiating a yellow, the peak 550 nm. Blue-chip installed in the LED-based Wanxing reflection in the cavity, covered with a resin mixed with YAG thin layer, about 200-500 nm. LED-based tablets issued by the Blu-ray absorption part of the phosphor, the phosphor another part of the Blu-ray and a yellow light mixed, can be a white. Now, the InGaN / YAG white LED, YAG phosphor by changing the chemical composition of the phosphor layer and adjust the thickness of the 3500-10000 K color temperature can be colored white. This blue LED through the method by white, constructed simple, low-cost, high technology is mature, so use the most.

In the 1960s, the use of science and technology workers semiconductor PN junction of The principle of developing a LED light-emitting diodes. At that time, the development of LED, the materials used are GaASP, its luminous color is red. After nearly 30 years of development, and now we are very familiar with the LED, has been sent to red, orange, yellow, green, blue, and other shade. However lighting necessary for white LED light only in recent years to develop, readers here to tell us about lighting with white LED.

The LED display screen and video display into the text by LED matrix blocks. Graphic display can be displayed with computer, English, Chinese text and graphics, Video screen using microcomputer control, graphic, image, with real-time, synchronization, clear information dissemination way play all kinds of information, but also shows 2d, 3d animation, videos, TV, VCD programs and live. The LED display screen display bright colors, stereo sense is strong, such as oil, such as films, widely used in finance, taxation, industry and commerce, telecommunications, sports, advertising, corporations, transportation, education system, station, port, airport, hospital, shopping malls, hotels, Banks, securities market, market, and construction management of industrial enterprises, Christie's and other public places.

The LED display can display the change of digital image; text, graphics, Not only can be used for indoor environment can also be used in outdoor environment, projectors, LCD TV wall, and the incomparable advantages.

LED by the wide attention and rapid development, and it is the advantages of itself. These advantages in is: high brightness, working voltage, low consumption, miniaturization, impact resistance and long service life and stable performance. LED the development prospect, is currently towards a higher brightness, higher resistance to climate, higher and higher light shine density evenness, reliability, the direction of development. Full-color

The classification of the LED display

1, the color can be divided into gezer

The single color display: single colors (red or green).

Double colors: red and green screen, double colors gray, can show 256 levels 65536 colors.

Full-color display: red, green, and blue, gray level 256 gezer full-color display screen can show more than 1,600 colors.

2, according to the classification of display devices

LED digital display: display device for seven yards, suitable for making the clock display screen, interest rates, digital electronic display screen.

Pictures of LED dot matrix LCD display device is composed of many: evenly composed of light emitting diode matrix display module, suitable for broadcast text, images of information.

LED video display: display device is composed by many light-emitting diodes, video, animation shows various video files.

3, by using occasions classification

Indoor display: light point is lesser, general Φ 3mm - Φ 8mm, display area of general several ten square meters to.

Outdoor screen area to several hundred square meters general dozens, high brightness, can work under the sun, in the wind, rain, waterproof function.

4 points, according to the classification of light in diameter

Indoor screens: Φ 3mm, Φ 3.75 mm, Φ 5mm,

Outdoor screen: Φ 10mm, Φ 12mm and Φ 16mm Φ, 19mm, Φ 20mm, Φ 21mm, Φ 22mm, Φ 26mm

The basic unit of the light outdoor screen for led light cone tube, the principle is a group of red, green, and blue light emitting diode sealed in a plastic tube in common

5. Display horizontally scrolling, static, vertical scroll and flip shows, etc. Single block module control drive 12 (maximum control and block), 16X48 matrix 8X8 matrix (or 32X48 matrix), is a single block of MAX7219 (or PS7219, HD7279, ZLG7289 8279 and other similar LED display driver module) 12 times (or 24 times)! Can use "cascade" means any bitmap big screen composed. Show good effect, low consumption, and the cost of using MAX7219 circuit is lower.

The LED display inspection method,

See appearance, specifications, screen body flatness, screen the attachment within

2 look bad, after the light screen is not in scope, the screen (generally now basically no)

Color consistency, displays text display is normal, the picture to screen, full-color play white, red, green and blue.

Technical advantage

Existing common indoor full-color scheme comparison:

1 the matrix modules: design, color dot matrix LCD by indoor artifacts

Advantage: the cost of raw materials, production and processing of the most advantage of simple process, quality is stable.

Faults: color consistency, Mosaic phenomenon, serious effect.

2. Single lamp schemes for solving the bitmap screen color: for outdoor screen technology,

a scheme of pixels, outdoor multiplexing technique (also called pixel sharing technology, virtual pixels to indoor display technology) transplantation.

Advantage: color consistency than bitmap module of good way.

Weakness: the effect not beautiful, color mixing, horizontal Angle and have off color. Process is relatively complex, anti-static high. Actual pixel resolution do 10,000 more difficult.

Features

? Compatible with MCS-51? Products

? 8K Bytes of In-System Programmable (ISP) Flash Memory

? 1000 Write/Erase Cycles

? Fully Static Operation: 0 Hz to 33 MHz

? Three-level Program Memory Lock

? 256 x 8-bit Internal RAM

? 32 Programmable I/O Lines

? Three 16-bit Timer/Counters

? Eigh t Interrupt Sources

? Full Duplex UART Serial Channel

? Low-power Idle and Power-down Modes

? Interrupt Recovery from Power-down Mode

? Watchdog Timer

? Dual Data Pointer

? Power-off Flag

Description

The AT89C52 is a low-power, high-performance CMOS 8-bit microcontroller with 8K bytes of in-system programmable Flash memory. The device is manufactured using Atmel’s high-density nonvolatile memory technology and is compatible with the industry standard 80C51 instruction set and pinout. The on-chip Flash allows the programmemory to be reprogrammed in-system or by a conventional nonvolatile memory programmer.By combining a versatile 8-bit CPU with in system programmable Flash on a monolithicchip, the Atmel AT89C52 is a powerful icrocontroller which provides a highly-flexible and cost-effective solution to many embedded control applications.The AT89C52 provides the following tandard features: 8K bytes of Flash, 256 bytes of RAM, 32 I/O lines, Watchdog timer, two data pointers, three 16-bit timer/counters, a six-vector two-level interrupt architecture, a full duplex serial port, on-chip oscillator,and clock circuitry. In addition, the AT89C52 is designed with static logic for operation down to zero frequency and supports two software selectable power saving modes.The Idle Mode stops the CPU while allowing the RAM, timer/counters, serial port, and interrupt system to continue functioning. The Power-down mode saves the RAM contents but freezes the oscillator, disabling all other chip functions until the next interrupt or hardware reset.

In the Counter function, the register is incremented in response to a 1-to-0 transition at its corresponding external input pin, T2. In this function, the external input is sampled during S5P2 of every machine cycle. When the samples show a high in one cycle and a low in the next cycle, the count is incremented. The new count value appears in the register during S3P1 of the cycle following the one in which the transition was detected. Since two machine cycles (24 oscillator periods) are required to recognize a 1-to-0 transition, the maximum count rate is 1/24 of the oscillator frequency. To nsure that a given level is sampled at least once before it changes, the level should be held for at least one full machine cycle.

Interrupts

The AT89C52 has a total of six interrupt vectors: two external interrupts (INT0 and INT1), three timer interrupts (Timers 0, 1, and 2), and the serial port interrupt. These interrupts are all shown in Figure 10. Each of these interrupt sources can be individually enabled or disabled by setting or clearing a bit in Special Function Register IE. IE also contains a global disable bit, EA, which

disables all interrupts at once. Note that Table 5 shows that bit position IE.6 is unimplemented. In the AT89C52, bit position IE.5 is also unimplemented.

User software should not write 1s to these bit positions, since they may be used in future AT89 products. Timer 2 interrupt is generated by the logical OR of bits TF2 and EXF2 in register T2CON. Neither of these flags is cleared by hardware when the service routine is vectored to. In fact, the service routine may have to determine whether it was TF2 or EXF2 that generated the interrupt, and that bit will have to be cleared in software. The Timer 0 and Timer 1 flags, TF0 and TF1, are set at S5P2 of the cycle in which the timers overflow. The values are then polled by the circuitry in the next cycle. However, the Timer 2 flag, TF2, is set at S2P2 and is polled in the same cycle in which the timer overflows.

Reference data:

1. the ATMEL company AT89S52 technical manuals

2.Shenzhen Development Co., Ltd. AT89C52

3.Fudan University Press, single-chip microprocessor theory, application and test ZHANG You-de, etc.

开关稳压电源-外文翻译

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