How do indoor LED screens work?
The basic operating principle of indoor LED screens is dynamic scanning. The procedure of display control is to first examine the font information from the statistics reminiscence, and then write the statistics to the led dot matrix via the serial or parallel port of the mcu, after which scan. – the dynamic scanning scheme saves driving force additives compared with the static show scheme, but the refresh frequency is required to be better than 50 hz to avoid flicker of the displayed photograph or textual content. Due to the restrict of refresh frequency, a single chip microcomputer can manipulate the quantity of show additives is much less.
Now the big display screenindoor LED screens display has been increasingly broadly used. There may be then the orderly, fast manage of the display through the hundreds or heaps of led dotes. There is then the radio. Dual cpi.Twin ram scheme, fpga scheme and so forth have been efficaciously carried out; the display control method of those schemes is still examine before write. This scheme to open any other idea :.. The performance of show manage may be substantially advanced by way of using one analyzing instruction to finish analyzing and writing in one step, and the circuit is simple.
1 the working principle of indoor LED screens
The simple running precept of indoor LED screens is dynamic scanning. Dynamic scanning can be divided into row scanning and column scanning. The common way is row scanning. Line scanning can be divided into 8 line scanning and sixteen line scanning. – in line scanning mode, each led lattice piece has a hard and fast of column power circuit, and there ought to be a latch or shift check in in the column drive circuit, which is used to latch the font information of the content to be displayed. In line scanning mode, the equal row control pins of the equal row of led dot matrix are related to a line, a total of eight lines, and subsequently connected to a row drive circuit; there must additionally be a latch or shift sign in in the line power circuit to latch the road scan sign.
The column force circuit and row pressure circuit of indoor LED screens are generally managed via single chip microcomputer, and the not unusual single chip microcomputer is mcs51 series. The content material of the led display screen is usually saved within the outside statistics memory of the microcontroller inside the form of font mode, and the font mode is an 8-bit binary quantity.
The scm manage technique of indoor LED screens screen is first examine after which write. In line with the sequence of led dot matrix at the screen, the mcu first drives the latch at the column of the primary led dot matrix in the first row, writes the font records examine from the external facts reminiscence, after which on the second, the 0.33….. Until the ultimate piece of this row is finished writing the font information, the mcu will drive the latch to write the line scan sign of this row, so the first row of the primary row and the light emitting diode associated with the font statistics is lit. ⒉ the second row is the first row, and the 0.33 row is the first row….. Until the final row, row 1, lighting fixtures up. After the first row of every row is lit up, the display is not on time for a time period, after which the screen is black. On this manner, the unmarried-chip microcomputer can test and control the led show.
The single chip microcomputer to the indoor LED screens inside the 2nd row of scanning manage, the 1/3 row of scanning manipulate…… Till the scan manage in line eight, the manner is similar to that in line ⅰ. After the manipulate method of all eight strains is finished, the led show display additionally completes the complete display of 1 body photograph.
Although the indoor LED screens is lit line by means of line in step with this working mode, only one line is lit at a time, but so long as every line can be lit extra than 50 times in keeping with 2d, this is, the refresh frequency is better than 50 hz, the picture displayed on the led show remains a full-screen strong photo due to human visual inertia.
2 indoor LED screens of the traditional manipulate method
The manage circuit of indoor LED screens is summarized and compared in reference [1]. Amongst them, the show control circuit works in line scanning mode, and the column control circuit is split into categories. Inside the column control circuit, a form of chip including 74ls377 is used because the latch of the column driving force circuit. The cpu writes font information to the latch of the column driver circuit via the parallel bus. The alternative type is to apply a chip inclusive of shift check in 74ls595 as the latch of the column motive force circuit. The cpu writes font statistics to the latch of the column driver circuit thru the serial bus.
In both parallel bus manage and serial bus control, the operating system is to first assign a fee to the records pointer dptr, and then the accumulator a reads the kind facts from the outside information memory ram in step with the data pointer dptr. Then, while the bus is parallel, the facts pointer dptr is assigned a fee, after which the cpu will write the font statistics within the accumulator a to the latch of the led lattice array driving force circuit in keeping with the statistics pointer dptr. In the case of serial bus, the cpu will write the kind information in the accumulator a to the latch of the led lattice array driving force circuit through the serial port.
In standard display manipulate, the microcontroller used more is mcs51 collection. Assuming that the crystal frequency of the scm device is 12mhz and the system cycle is l us, it’ll take more than ten instances for the above manipulate techniques to complete the show manage of l led dot matrix pieces.
