In the digital clock circuit, the second and minute counts are completed by two 60-base synchronous increasing counters, which are advanced by 24/12Make synchronous increment counter to realize hour count. The second, minute, and hour counters are cascaded synchronously. Switch K control hours 74hc00d is what chip 24 and 12 count mode selection.
Time takes 24 hours as a cycle; Display hours, minutes, seconds; It has the time calibration function, which can be calibrated separately to the time and sub-time, so that it can be calibrated to the standard time; The timing process has the function of timing, when the time reaches the hour 5 seconds before the buzzer time; In order to ensure the stability and accuracy of the timing, the crystal oscillator must provide the watch time baseQuasi-signal.
is usually 9), which returns to the minimum value (usually 0) and triggers a carry signal that adds 1 to the next counter. The base 60 counter is the same, but the upper limit of the current number plus 1 is changed from the decimal 9 to the base 60 59, when the number reaches 59, it will return to 0 and trigger a carry signal, so that the next counter plus can be implemented using a display method such as a digital tube or through the circuit.
A base 60 counter can be constructed with a 74LS161 chip and an appropriate logic gate circuit. 74LS161 is a 4Bit-synchronous binary counters allow for easy counting from 0 to 15. In order to achieve the base 60 count, 74hc00d what chip we need to cascade the two 74LS161 and add the appropriate logic circuit. First, set the first piece 74LS161 (called counter A) to a mode 10 counter.
Use two sexagesimal circuits to synthesize a double sexagesimal circuit with a carry between the two sexagesimal circuits. The double sexagesimal circuit uses CD4060, resistance and crystal oscillator to connect into a frequency division -- crystalVibration circuit. The frequency division - crystal oscillator circuit uses 74HC51D and 74HC00 and resistors to connect into a timing circuit. The timing circuit uses 74HC30 and the buzzer to connect to the hourly timing circuit. The hour signal circuit.
Multi-functional digital clock (a) Basic function: time should be 12 times 1, minutes, seconds 60. Accurate timing, showing the time of the minute and second in digital form. Correction time. (2) Extended function: timing control. Imitation radio time function. Automatic time on the hour. Touch the hour. (3) Music function: The arrival point will automatically tell the time, there is music to enjoy.
Pin description of each input and output signal: CLK: clock signal RST: system resetSignal, low level active. After the clock reset, the value is 00, 00, 00. EN: Pause signal, low level effective, press the key, digital clock pause. S1: Adjust the hour signal, the low level is effective. Each time you press it, the hour increases by one hour. S2: Adjust minute signal, low level is effective. Each time you press, the minute increases by one minute.
Introduction (1) The digitalization of clocks and watches has brought great convenience to people's production and life, and greatly expanded the original function of clocks and watches. Such as automatic alarm timing, automatic ringing on time, automatic time program control, timed broadcast, timed opening and closingSometimes go in a hurry, in the blink of an eye, another year of college life is over. Looking back on the life of the university this year, plain and full of fun, helpless and with expectations.3, you may have this feeling: sometimes the class is only a few seconds, wake up do not know what the teacher cloud, resulting in the content of this lesson can not learn to understand. Therefore, we should grasp the class time well. It is not only necessary to understand what the teacher said, but also to record the teacher's explanation combined with their own experience. Take three to five minutes after class to review your notes and then focus on the next lessonIn the study of a class.
4, learning experience is through the careful learning of a kind of knowledge, their own feelings, is a kind of reading, practice after writing feelings, is the learning things to practice to practice to reflect on the learning content and record the text, similar to the summary of experience. Experience refers to the experience and understanding of work or study: ordinary people read, each has his own experience; Learning experience. We are in the learning stage, we should have like Edison, Balzac hard work, unremitting pursuit of the spirit, because only in this way, we can be realShow your goals and show your skills on the stage of chasing your dreams. On the road of learning, we can only master every bit of knowledge with diligence and steadiness in order to eventually succeed. After reading the basic standards, I have the following three overall impressions: (1) Close to the international accounting standards. The first chapter defines the legal status of the basic standards, as well as accounting objectives, accounting assumptions, accounting elements and accounting accounting methods. In this section, the accrual basis is included in the accounting assumptions, apparently influenced by the International Accounting Standards reporting framework (of course, the original basicThere are also guidelines).
Consists of 74CH51D, 74HC00D and resistance. The correction circuit has two parts: branch and time correction. The circuit is shown in Figure 6. (7) The crystal oscillator circuit consists of a crystal with 2 30pF capacitors, 1 4060 and a 10 megabit resistor. Pin 3 of the chip outputs a 2Hz square wave signal, and the circuit is shown in Figure 7. (8) The hourly timing circuit is composed of 74HC30D and buzzer, when the time is 59:50 to 59:59, the buzzer, the circuit is shown in Figure 8.
Chapter 5 Program design As long as the program has completed the initialization, timing, in the timing process judge pressKey situation, do the corresponding treatment. The process is as follows.
The design requires the second pulse as a signal source, constituting a digital clock, displaying seconds, minutes and hours with "time" function, that is, the time can be quickly preset with the whole point prompt function. One way to do this is to trigger a "music chip" every hour, or a few seconds before every hour, to emit a sound signal such as "yes, yes, yes, answer."
Course design digital clock, a total of 16 pages, 4088 words. The Foundation of Digital Electronic Technology is a basic course of electronic technology, which is the cornerstone of further study for our electronics students. tongThrough this course design can deepen the understanding of this course and the mastery of relevant knowledge, and at the same time can enhance the ability of independent thinking and operation.