Design of led display interface circuit for single-chip computer
There are many ways to design the single-chip LED display interface circuit. The following are the common points: ** 1. Parallel port display ** 1. ** Resource Usage ** - This method would take up a lot of port resources of the single-chip computer. However, using chips like the 8279 could achieve dynamic display, so it was relatively easy to write programs. However, it was not recommended for designs where the parallel port of the single-chip needed to connect to many devices, because it would exhaust the parallel port resources. 2. ** Principle example ** - For example, in some designs, if the C2051 single-chip computer was used, the cheap and easily available 74LS164 and 74LS138 could be used as expansion chips. The 74LS164 is an 8-bit serial-in and serial-out shift register. It can decode the serial data output from the C2051 serial communication port and output it on its parallel port line to drive the LED digital tube. The 74LS138 was a 3 - 8 decode that would decode the address signal from the single-chip processor and drive the corresponding LED. Due to the low current drive capability of the 74LS138, the final driver 2SA1015 was sometimes used as the address driver. The segments of the four LED were connected together, and their public end was gated by 74LS138 to achieve a dynamic scanning display mode. ** 2. The serial port is displayed ** 1. ** Resource utilization advantage ** - When the number of parallel I/O ports of the single-chip computer is limited and needs to be used for other more important purposes, you can consider using the serial port display. For example, the serial communication port of the 80C51 was a powerful and easy to use communication port that could be used for display driver circuits. With two serial communication port lines and two ordinary I/O ports, a 4-bit LED display circuit could be designed; with two I/O port lines, an 8-bit LED display circuit could be easily realized. 2. ** Program Writing Characteristics ** - When using the serial port for LED communication, the programming was quite simple. The user only needed to send the data to be displayed directly to the serial port sending buffer and wait for the serial interrupt. ** 3. Digital Tubes ** 1. ** Principle of display ** - The LED digital display was a display device that used a combination of LED light emitting devices to display characters. Usually, eight LED light emitting devices were used, of which seven were used to display characters and one was used to display the decimal point. It was called a 7-segment (also known as an 8-segment) LED digital display. In order to display the characters, the LED display had to be provided with a display segment code (or glyph code). The corresponding relationship between the code positions of each segment was related to the seven segments that formed the "8" character and the decimal point. 2. ** Connection Method ** - The LED digital display had a common positive pole connection method. ** 4. Other considerations ** 1. ** Current limiting resistance ** - The resistance in the circuit played a role in limiting the current, which was used to reduce the current flowing through the LED to prevent damage to the LED lamp. Take the red chip LED as an example, its working voltage range is 1.6V to 2.4V. If the power supply voltage is 5V, the appropriate series resistance should be calculated according to Ohm's law. For example, the voltage across the resistance is the power supply voltage minus the LED voltage drop (5 - 1.8 = 3.2V), and then the resistance value is calculated according to the expected current value (Assuming that the current through the LED is 3.2mA, the resistance value is 3.2V/3.2mA = 1k Omega). 2. ** Pull-up Resistors (if involved)** - The choice of the pull up resistance needed to balance power consumption, driving ability, and circuit speed. In order to reduce power consumption and chip sink current, the resistance value should be as large as possible; in order to ensure sufficient drive current, the resistance value should be as small as possible; in high-speed circuits, too large a pull up resistance may cause the signal edge to become smooth. Usually, the value of the pull up resistance is selected between 1k Omega and 10k Omega. 3. ** Filter-filter (if involved)** - There were two types of filter condensers: high frequency and low frequency. The high-frequency filter usually uses a 0.1 microF filter, which is used to short-circuit high-frequency noise and protect the circuit from interference. The low-frequency filter usually uses a 100 microF aluminum filter, which is used to filter out low-frequency ripples and stabilize the power supply. These are usually installed next to the power interface or high-power components, such as USB interface or stepping motor. Read more exciting novels for free
On the way home at dusk, how to answer the next sentence
On the way home at dusk, it could be followed by " looking up to see the moon " to create a feeling of stepping on the way home at dusk and looking up to see the moon. It could also be followed by " love holding the old house " to express the longing and concern for home when the sun set foot on the way home. It could also be followed by " warm place in the heart " to reflect the warmth of the heart when the sun set foot on the way home.
How to say in English a written reply to an invitation
The "written reply to the invitation" could be "Answer to the invitation in writing". <a href="/?from=ask_words" style="color:red" target="_blank">Read more exciting novels for free</a>
What are the novels similar to the number one beauty in Beijing?
The following were some novels that involved elements similar to the " number one beauty in Beijing ": - In one of the novels, the female protagonist's sister was the most beautiful woman in the capital. However, when she reached adulthood, she was abused to death by the young marquis. Then, the marquis's manor slaughtered her entire family to seal her mouth, and the female protagonist carried the mission of revenge. - In another novel, Fu You was known as the most beautiful woman in the capital. She was the youngest daughter of the prime minister's family. She had been engaged to the crown prince's cousin since she was young, but later fell in love with the cold and jade-like Jiang Huaizhi. - In another novel, the female protagonist was the most beautiful woman in the capital. After she married a poor scholar, the scholar used her family's power to become the prime minister and changed his heart. After the female protagonist was reborn, she would not repeat the same mistake. <a href="/?from=ask_words" style="color:red" target="_blank">Read more exciting novels for free</a>
How did Liu Ye say Yao Chen's name?
Liu Ye once said bluntly," Cao Yu is my buddy. When I was filming Love to Be Outstanding, I knew that they were together." The " she " here referred to Yao Chen, but Liu Ye did not mention Yao Chen's name in any other way. <a href="/?from=ask_words" style="color:red" target="_blank">Read more exciting novels for free</a>
The Book of Luoyang Famous Garden
Luoyang was located in the middle of the country, with the dangers of Xiaoshan Mountain and Mianchi. It could be considered the throat of Qinchuan and Longdi, and it was also a place that Zhao and Wei fought for. It was a place that the vassals of the four directions fought for. If the world was always peaceful, it would be fine. Once there was a war, Luoyang would always be the first to suffer. For this reason, I once said,"The rise and fall of Luoyang is a sign of peace or turmoil in the world." When Emperor Taizong and Emperor Xuanzong of the Tang Dynasty were in their heyday, there were more than 1,000 officials, nobles, and imperial relatives who built mansions in Luoyang, the eastern capital. In the later stages, they were displaced by the turmoil, followed by the tragic destruction of the Five Generations. Those ponds, bamboo forests, and trees were trampled by the chariots and turned into ruins. The tall pavilions and wide towers were burned by the flames of war and turned into ashes. They were reduced to ashes along with the Tang Dynasty, leaving nothing behind. Therefore, I once said,"The prosperity or destruction of the pavilion garden is a sign of Luoyang's prosperity or decline." Moreover, the peace or turmoil of the world can be seen from the rise and fall of Luoyang. The rise and fall of Luoyang can also be seen from the rise and fall of the pavilion garden. Then, is the work "Luoyang Famous Garden Record" a futile effort? Sigh! The officials were now promoted and appointed by the imperial court. They indulged their own selfish desires and did whatever they wanted, but they forgot about the peace or turmoil of the country. Could they retire and enjoy the pleasure of this garden in the future? The Tang Dynasty's final destruction was a lesson from the past! " Fairy Dream of Tang Shi: Fate of Peony " is equally wonderful. Everyone is welcome to click and read it!
What's the name of the novel?
" I Feed the Ancient Generals ". The novel " The General's Promotion " is equally exciting. Everyone is welcome to click and read it!
How to find a job at home?
If you want to find a job during the preparation of the home exam, you can consider the following ways: 1. ** part-time job **: - He could find a part-time job suitable for the public and postgraduate examinations, such as a part-time teacher position. Some places would recruit part-time teachers who were waiting for employment. For example, Wuchuan City in Zhanjiang had a situation where they were recruiting part-time teachers. They were required to work for at least one semester (September 2024-January 2025), and they were required to teach one to three classes per week from 4 to 6 p.m. on weekdays (Monday to Friday). The targets of recruitment included those who were waiting for employment. They had a college degree or above (relevant experience could be relaxed appropriately), and they provided free teacher training. 2. ** Freelance or online work **: - If you have certain skills, such as writing, designing, programming, etc., you can find related freelance jobs online. For example, he could take on projects on some freelance platforms and complete the work at home according to the project requirements and get paid. 3. ** Temporary Work **: - He could consider some jobs that did not require an interview or could even be settled on a daily basis. Although such jobs might not be stable, they were more flexible and could earn a certain income during the examination period. However, this type of work may be relatively lacking in security and career development prospects, such as some simple manual work or short-term data entry work. 4. ** Work related to family business **: - If the family had some small businesses or business activities, such as online stores, family workshops, etc., they could participate in them. They could work from home and accumulate some business experience. <a href="/?from=ask_words" style="color:red" target="_blank">Read more exciting novels for free</a>
The difference and connection between reaction heat and combustion heat
The heat of reaction refers to the heat released or absorbed by the system when the temperature of the product returns to the initial temperature of the reagent after the chemical reaction occurs under constant pressure and without non-expansion work. It is the heat released or absorbed by the system when the chemical change occurs in the process of constant temperature and constant pressure. The heat of combustion is the heat released when 1 mole of pure substance is completely burned to form a specified product at 101 kPa. The difference between the two was: 1. The heat of reaction was a broader concept, covering the heat changes in various chemical reactions, while the heat of combustion was specific to the reaction of complete combustion of matter and oxygen. 2. The heat of reaction occurs under the conditions of constant temperature, constant pressure, and no non-expansion work. The heat of combustion is clearly defined as the heat of complete combustion of 1 mole of pure substance under 101 kPa. 3. The calculation of the heat of reaction is related to the type of reaction, the amount of substance, and the degree of reaction. The heat of combustion is only the heat of the complete combustion of 1 mole of pure substance to produce a specified product. The connection between the two was that the heat of combustion was a special form of reaction heat. The measurement of the heat of combustion could help to calculate the heat of formation of a compound, the heat of reaction of a chemical reaction, and the bond energy. The data of the heat of combustion could provide a basis for the calculation and research of the heat of reaction. <a href="/?from=ask_words" style="color:red" target="_blank">Read more exciting novels for free</a>
The novel of the eldest grandson of the Rongfu of the Red Chamber
According to the information provided, there was a novel that involved the eldest grandson of Rong Mansion. In it, Jia Ying was reborn as the eldest grandson of Rong Mansion and was the first heir of Rong Mansion. However, the people of Jia Mansion wanted to kill Jia Ying for money and tried every means to prevent Jia Ying from inheriting Rong Mansion. There was also a series of plots related to Jia Baoyu. However, based on the available information, the specific name of this novel was not clear. Sorry, I can't accurately answer the specific information of the novel about the eldest grandson of Rong Mansion. The novel " Master of the Red Chamber " is equally exciting. Everyone is welcome to click and read it!
Ran Yingying Exposes Huang Xiaoming and Ye Ke's Romance
When Ran Yingying talked about Huang Xiaoming and Ye Ke's relationship in the live broadcast, she said that Huang Xiaoming loved children and loved his family very much. She also said that the couple often had family gatherings. As long as Huang Xiaoming felt happy, she would wish them well as friends. However, Ran Yingying's words raised many people's doubts. Some people thought that if Huang Xiaoming really loved the child, he would not have gone on a trip with Ye Ke when the child had a fever and Yang Ying was taking the child to see a doctor alone. If he loved his family, he would not have divorced Yang Ying and been with Ye Ke. Moreover, after the official announcement of this relationship, many gossip incidents were triggered. Some netizens reported Huang Xiaoming to the government, saying that he did not establish a positive image as a public figure, and that his girlfriend's high-profile flaunting of wealth led to a bad social atmosphere. This series of events greatly reduced the public's impression of Huang Xiaoming. While waiting for the TV series, he could also read the exciting content related to this site!