The commonly used displays in the single-chip microcomputer include LED light-emitting diode display, LCD liquid crystal display, CRT cathode ray display, etc. The display structure of the LED display is a segment display, that is, a 7-bit segment display, an 8-bit segment display, a rice-shaped display, etc., an 8-bit segment. The display shows one more decimal point display bit dp than the 7-bit segment display. For example, LED display such as digital tube commonly used in single-chip technology applications has a digital tube, two digits, and four digital tubes. The display structure of the LCD display is dot matrix display, that is, 8 & TImes; 8, 16 & TImes; 16, 32 & TImes; 32 and other products, the more bits of the dot matrix, the better the display effect. Commonly used LCD liquid crystal displays are LCD1602 and so on.
First, the structure and working principle of LED digital tubeThe basic unit of LED digital tube is a semiconductor light-emitting diode. The 7-segment LED digital tube is a 7-segment LED that is arranged in the word "æ—¥". According to the top horizontal, the letter a~ is arranged clockwise. g means that it can display 0~9 ten digits, and can also display simple English letters such as l, o, a, g and so on. The 8-segment LED digital tube is based on the 7-segment and then added a dot in the lower right corner of the digital tube with the letter dp, which is used to display the decimal places.
According to the different connection forms of the eight light-emitting diodes, the LED digital tube can be divided into two types: a common anode and a common cathode, and the anodes of the eight light-emitting diodes are connected together as a common anode LED digital tube; The cathodes are connected together and are called common cathode LED digital tubes. In order to make the LED of the LED digital tube emit light numbers or letters, for the common cathode LED digital tube, it is necessary to input a high level at the input end, that is, the input is "1", then the LED emits light, and input low level input at the input end. When it is "0", the LED does not emit light, and the LED digital tube for the common anode is just the opposite. For example, taking a common cathode LED digital tube as an example, if the LED digital tube displays the number "5", the light-emitting diodes of the b, c, f, and g segments are illuminated, and the value is "1", while the other segments a, d The LEDs of the e, dp, and dp segments do not emit light, and the value is “0â€. The assignment result is 01101101B in the order of dp, g, f, e, d, c, b, and a, and the conversion is hexadecimal number 0x5bH.
Second, the principle and function of the latchThe latches are all transparent D-type latches. When enable (G) is high, the Q output will vary with the data (D) input. When enable is low, the output will be latched at the established data level, the output control does not affect the internal operation of the latch, ie old data can be maintained, even when the output is turned off, new data can be placed .
If the LED digital tube is used without adding a latch, especially in the case of dynamic display, the display of the LED digital tube may be irregularly beaten. In addition, the use of latches can make the CPU less time consuming, occupy less output ports of the microcontroller, and can support port multiplexing. Therefore, in order to ensure the display signal effect of the LED digital tube, when using the LED digital tube, a latch is generally used, and the commonly used latches are 74LS373, 74HC573, and the like.
It is composed of AT89C52 single-chip microcomputer, two 74HC573 latches, three two-digit digital tubes, reset circuit and crystal oscillator circuit produced by American ATMEL Company. The P0 port is respectively connected with the D port of the bit selection and segment selection latches, and the selected Q ports are respectively connected with the a~dp of the LED digital tube, and the selected Q ports are respectively connected with the chip selection ports of the LED digital tube. . The bit selection terminal is connected with the single chip microcomputer P2.0, and the segment selection terminal is connected with the single chip microcomputer P2.1.
(1) Static display of LED digital tube
The static display of the LED digital tube means that multiple LED digital tube positions are selected independently in the system, and the segment selection ends are connected together. At the same time, the signals of the segment selection terminals are the same, and the displayed symbols should be the same, but the bit selection terminal can control which LED digital tube emits light. For example, taking the common cathode LED digital tube as an example, when the bit selection and the segment selection end are "1", it is turned on, when it is "0", it is turned off, when the common cathode digital tube is "1", the light is emitted, and when it is "0", it does not emit light.
...... //52 series MCU header files
Sbitduan=P2^1, wei=P2^0; //Declare the latch end of the segment select and bit select latch
Voidmain()
{wei=1;//Open the bit selection
P0 = 0xFE; / / send signal 11111110B, even if the first LED digital tube shines
Wei=0; //close the bit selection
Duan=1;//Open segment selection
P0 = 0x5bH; / / send signal 01101101B, that is, let the LED digital tube display the number "5"
Duan=0;//Close segment selection}
(2) Dynamic display of LED digital tube
The dynamic display of the LED digital tube is also called the dynamic scanning display of the LED digital tube. The afterglow of the LED tube and the persistence of the human eye vision make people feel like the digital tube is displayed at the same time, but in reality there is only one digital tube at a certain moment. The data is displayed and the display time is short, generally between 1~10MS. The dynamic display of the LED digital tube, the CPU should periodically scan and refresh the display, generally suitable for occasions with a large number of display bits, occupying fewer ports, and the circuit design is relatively simple, but the editing is more complicated.
How is a mezzanines definition ?
The mezzanines are supported by shelves and can be designed into multi-storey floors (usually 2-3 floors). There are stairs, handrails and elevators. This is a simple shelf that makes full use of space. Build an intermediate loft over existing racks or worksites to increase storage area. Generally, light foam and small and medium-sized goods or goods with a long storage period can be placed on the mezzanines. It is suitable for situations where the warehouse is high, the goods are small, manual access and storage are large. The floor support racks have a complete range of specifications, and the mezzanines includes flat plates, checkered plates, steel chrome plates, and wood panels. Light trolleys or pallet traction trolleys are generally used on the mezzanines.
What is the advantage of a mezzanine floor ?
1. The mezzanines is a full-scale structure, with a special steel floor slab
2. It can be flexibly designed into two or more layers to make full use of space
3. The mezzanines is suitable for storing small batches of multi-variety goods
Mezzanine Shelves,Mezzanines For Warehouse Storage,Space Saving Mezzanines,Storage Metal Mezzanines
Wuxi Lerin New Energy Technology Co.,Ltd. , https://www.lerin-tech.com