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    LED lighting in the landscape lighting has gone through ten years of history, and its control technology has developed in several stages, each stage to solve the many problems at the same time raises new questions each point. The following LED control technology to further discussion.

    1, LED display driver control over the way the transfer mode. Using the 74HC595, DM115, MBI5026 chip serial shift, and similar communication method, each chip cascade, the cascade of each lamp. Both of which also have constant current constant voltage drive drive. The means of communication leads to the question is too much light on the signal line, to 4 or 5 (including the ground), not only to increase the company’s production and commissioning of the time cost and material cost, the project also increased the time cost of installation and material costs , which leads to the increase in failure rate, the biggest problem is the front end of a string of lamps or signal damage to the chip, the back-end is also affected. The advantage is of course not be denied, HC595 cheap, chips mature, light and easy to program design, market, multi-controller support.
    2, DMX512 protocol RS485 bus form, plus the chip microcontroller using RS485 (MCU) in the way of forming a bus hang 512 points RS485 effective parallel system, each lamp to do with the address number to each receiving different data, to adjust The purpose of light color. The relatively one way, reducing the root of the number of signal lines, and basic elimination of the lighting of a lamp failure of the phenomenon of follow-up, the signal transmission distance is relatively far distance between the lamp and the light from a few meters, tens of meters of the restrictions. However, this approach also brings other negative issues, first, the high cost of DMX decoder, a little higher than when purchased, own and needs good engineers, and number of each lamp was not addressed and the need to increase number automatically signal line, there is sometimes a problem of bus decoder to find difficult problems, then there is a limited number of each host controller with lights to increase the overall system hardware cost. Impact of these negative issues are also a large number of DMX512 system, the use of reason, can only be used in some high-end projects.
    3, in-line communication, 3 port, 6 port drive the proliferation of chip LED lamp design makes it easier. Single chip representatives ZQ1111, TLS3001, TM1803, SDMX5124 such, they are between the chip and the chip with the signal line through the single serial cascade, the chip I / O PWM output can be automatically scanned, so the signal line The communication speed can be greatly reduced, the distance between the chip and the chip is less than 2 Mi Neiji This eliminates the need for the HC245. Such chips to meet both the high gray (256 level) data transmission, but also increase the number of series lights. Current light source and the light string (section) has been widely used, guardrail section because of the need to use more chips, and a chip using mature and stable, and gradually replace also need a process. Advantage of the phase of the innovation is obvious, for the point light source and the light string (section) is only designed three output ports, internal with PWM output, the data transmission efficiency is greatly improved data transfer speed greatly reduced, thereby improving reliability, Province to the amplification components, an increase of the number of cascade, lighting greatly improved design flexibility. However, the fly in the ointment is there, first of all, most chips are just listed soon, there on behalf of the consideration of stability and improvement of stability of prices and slightly expensive side, single lamp requires the application of multi-chip limited. Secondly, transmission of data or the use of cascading, or signal failure of front-end chip, the chip and the signal back, once again, the controller on the market is not a lot of support, customer choice is limited.
    4, DC-carrier modulation communication applications for LED lighting control system. DC-DC power carrier line by definition is loaded in the waveform, the transmitted signal, to power, signal transmission lines with the purpose of the lamp so no need to use the system signal line, only the power cord. Under which to describe the signal line on the lighting system without the advantages of: 1. To reduce the factory when the welding process lights, the time cost of connecting signal lines and signal lines of the material costs, 2. To reduce light engineering connections, the time the signal line layout cost and signal line material costs, 3. improve the lighting system of commissioning, maintenance, speed, single lamp is broken does not affect other lamps, failure to determine visually, which look bad light which lights. The basic principle is the carrier power modulator switching power supply input connection, the signal input connector LED master controller output, the output of a band carrier signal after the power lines, each parallel to this set of lights on the power line within each light and then the power line carrier demodulator signal demodulated by the microcontroller (MCU) after controlling lighting, back to using a dedicated integrated chip demodulator after filtering the power supply to the lamp voltage for the rectifier electricity. Therefore, each switching power supply with a carrier modulator, lamps do not need to signal line. Carrier’s wide range of current rates can be chosen at random from 0-1MHZ the modem can be designed to be compatible with DMX512 DMX512 protocol agreement or forward signal, the main market of the DMX512 controller can be used, greatly expanding customer choice. DC carrier also has its drawbacks exist, 1. Because of the power line loads the signal, resulting in larger power line impedance, line voltage drop becomes larger, so the need to improve power supply input voltage a few volts in order to meet the back-end full-power lighting load voltage requirements, 2. for a Bus line, lamps need to write the address number to distinguish the signal data location, 3. due to carrier modulation and demodulation devices exist, so the total cost of the system will not be cheaper than the 1,3-system, but below the second phase of the DMX512 system.

    Here, more than 4 points on the performance and price comparisons, the price, the first is between 1 and 4 (3) and 2, and in performance, then 4 points is the most superior. When is the most cost-effective DC-carrier communication system.

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