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7 segment rolling display using a computer works

2016-12-14 08:24  
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This article is a 7 segment rolling display using a computer works.The principle is simple but effective.For you to more effectively grasp this principle, we recommend that you read the text combines schematic.Here, a simple hardware circuit and software used to interface a 7-segment display rolling basis.Computer printer port provides a set of points and a number of input lines and a number of other people as the output line.Some lines open collector type can be used as an input line.The circuit shown here can be used to connect any type of computer's printer port.25-pin parallel port connector supports the PC is a combination of three ports.H-37ah from 378 different addresses.Line 7 port 378 h (pin 2 to the output of the circuit for the code segment display through IC1. Remaining line port 378 h (Pin 9) and four lines of port 37 ah (pin 1,14,16,17) isto display the number (a) by IC2. bits D0, D1 and D3 are connected to port pins 14 and 37 ah 17 "D" connector is inverted by the computer before the application to the pin and the data bit D2 is not inverted, so to get aIn any three-pin logic high, we must send logic 0 output to the corresponding pin port 37 ah Another important concept to illustrate the project is time-division multiplexing. Please note that all five share a 7-segment displaycommon data bus. PC where the first one 7-segment code / character on the data bus, so that only the first 7-segment display after a delay of a few milliseconds, 7-segment code digits / characters are replaced in the future concession / digital, but this time only the second display digit is enabled. displays all characters / numbers in this way, the cycle is repeated over and over again because of this repetition at a fairly high speed, there is a misconception that all the figures /characters continue to be displayed. DISP1 body should be placed in the least significant bit. IC1 (74 ls244 ) is an octal buffer is mainly used to increase the drive capability. It has two sets of four three-state buffers and the non-inverted output buffer is composed of twoan active low enable line. IC2 (75492) can drive up to six 7-segment display. (seven common-cathode display drivers can be used in other places in this section describe ULN2003.) This program is used to scroll through the list DISP.Cgiven above. Whether News / character display (five character display), which are isolated and stored in an array, then these are decoded. decoding software is very simple. is the replacement of the binary equivalent of the character display code.The code shown is a byte, with the appropriate bit to open, for example, to display the character "L", a segment is opened f, e and d. This corresponds to 111000 binary or hexadecimal 38. Please note that only a limitedThe characters can be composed using the 7-segment display. characters such as M, N and K can not form normally if you are reading this first principle, the proposed Duokanjibian, grasp this principle.

7 segment rolling display using PC

7 segment rolling display using PC

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