Design of LED electronic display screen based on MCU
Author:Wang Jiaolong Time:2021-09-12 16:51 Browse(632)
I have done such a graduation project, 16 * 64 dot matrix display screen, can be a variety of display, time, temperature and other functions.
I have done such a graduation project, 16 * 64 dot matrix display screen, which can display all kinds of functions, such as time, temperature and so on.

Design of LED electronic display screen based on MCU

to give you a reference: you can go to my blog to download: LED dot matrix Chinese character display screen overview. Due to the time constraint, the production of this competition was only made in turn in order to reduce the difficulty of production, In actual use, the number of words displayed can be expanded according to this principle.
the design and production are mainly used in the propaganda column of the University.
for example, various information of undergraduate evaluation, important notice of the University and college, Weather forecast and other information.
system design hardware circuit (1) system composition: main hardware circuit: LED dot matrix bar screen is composed of 16 8 * 8 LED dot matrix blocks.
forming 16 * 64 rectangular dot matrix, AT89S51 is used as the control core.
other main hardware of the display screen are as follows: 1. The 8-bit shift register 74HC595 with latch output is used as the column line drive input of LED; ② Four six decoder 74ls154, as the decoding choice of LED line (considering the cost in the actual production, it is changed to two 74HC138 combined); ③ The triode 9012 is connected to 16 output terminals of the four six decoder, which is used as a switch to drive the line of LED.
Fig. 2 the pins of AT89S51 related devices in the minimum system of AT89S51 single chip microcomputer are as follows: pa0-pa3 is connected to the input port a of 4-16 decoder.
b, C, D; Pb0-pb3 is connected with the input ports Si, SCK and RCK of 74HC595; Pd6-pd7 is used as serial port communication, 16 outputs composed of two 38S decoders (RXD and TXD) 74LS138 are connected to the base B of 16 9012 triodes,The emitter e is connected to a 5V power supply, and the collector C is connected to 16 row line control terminals of three Chinese character lattice.
the 48 column data line driver of the lattice is composed of six 74HC595 cascades.
the q'h pin of the former 74HC595 is connected to the Si PIN of the next one, and the SCK, RCK, srclr, srclr, and so on of each chip (2) the LED lattice of LED lattice block 8 * 8 in Figure 3 is a monochrome row common cathode module.
the working voltage of a single point is 1.8 V, and the forward current is 8-10 ma.
the total current is 640 Ma when the device is illuminated statically (64 points are all on).
the total voltage is 1.8 v, The total power is 1.15 W.
the dynamic state depends on the scanning frequency (1 / 8 or 1 / 16 sec).
the instantaneous current of a single point can reach 80-160 ma.
16 * 16 lattice static state 16 * 16 * 10mA.
the dynamic state single point current is 80-160 ma.
the actual test: the current of the whole machine is 700 MA (2) shift register 74HC595 Fig. 4 74HC595 internal logic diagram 74HC595 is an 8-bit shift register with latch output.
the pins are shown in In the figure below, Si is the input terminal of serial data; VCC and GND are power supply and ground respectively; RCK is the input clock of the storage register, SCK is the input clock of the shift register, SCLR is the input clear of the shift register, q'h is the output of the serial data, G is the output enable control of the input data, QA ~ QH is the parallel output of the serial data.
the data input from Si port is input into 74HC595 under the action of the rising edge of SCK pin of the shift registerUnder the action of rising edge of RCK pin, the input data is locked in 74HC595. When G is at low level, the data is output in parallel.
SCLR is the input clear end of shift register.
(3) 74HC138 and its driving circuit diagram 5. 74HC138 and its driving circuit diagram 4-16 line decoder (composed of two 74HC138 blocks).
its pins are shown in the figure, a, B, C and D are the decoding inputs, The range of values is from 0000 to 1111. Y1 ~ Y15 are the output pins corresponding to the four input pins a, B, C and D. the selected line uses the output low level, and the unselected line uses the output high level. G1 and G2 are the enable terminals, Only by inputting the corresponding D low level can the decoder work normally.
the driving triode is 16 9012.
welding with universal board.
two software designs the program design of single chip microcomputer, which is mainly responsible for data receiving, data processing and data processing in LED dot matrix Chinese character display system This is a general subroutine.
it is called in the display subroutine. The function is that the shift register 74HC595 receives the lattice line data sent by the single chip microcomputer, moves to the corresponding position bit by bit, and then latch and output. At the same time, it switches the four or six decoders, Control the display of the screen.
part of the program: initialization program: # include # define uchar unsigned char # define uint unsigned int # define speed 3 uchar Col.
disow; uin,
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