Abstract: In addition to the function of clock, the multi-function electronic clock can also include the function of detecting the ambient temperature. Temperature is one of the most basic environmental parameters. In the production and daily life of various industries, the measurement and control of temperature has always occupied a very important position. At present, a typical temperature detection control system consists of an analog temperature sensor, a D conversion circuit, and a variety of microcontrollers. Because the analog signal output by the analog temperature sensor must be converted into a digital signal through the AD conversion link before it can be read and written with the microprocessor interface such as a microcontroller, the hardware circuit will be more complex and the cost is higher. The new single-wire bus digital temperature sensor represented by DS18B20 integrates temperature measurement and AD conversion, this kind of sensor can directly output digital quantity, and at the same time, the circuit structure of the interface with the single-chip microcomputer is very simple, and can be widely used in the occasion of long distance and many node distribution, which has strong promotion and application value.
Keywords: electronic clock;MCU;Analog signals.
Determination of system functions.
The system has the functions of time, stopwatch, and alarm clock, and can set the time, stopwatch, and alarm clock, and the alarm clock is reminded by a buzzer. It is required that the timing accuracy be as high as possible. The display format is:
Time: "Hour" (1st, 2nd digit), "Minute" (3rd, 4th digit), "Second" (5th, 6th digit);
Stopwatch: "Hour" (1st, 2nd), "Minute" (3rd, 4th), "Second" (5th, 6th);
Alarms: "Hour" (1st and 2nd digits), "Minute" (3rd and 4th digits), "Second" (5th and 6th digits).
System operating instructions.
1) Press the start button to automatically enter the time display, start is 0, press the k1 key to enter the change time, the flashing bit is the changeable bit, press the k2 key to adjust the change bit, the k3 key is the auto-increment key, the k4 key is the auto-decrease key, press the k1 key to confirm the modification success after the modification is successful;
2) Press the K2 button to enter the stopwatch function, press the K2 button again to start the timer, the K3 button is the stopwatch pause button, and if you continue, press the K2 button, and the K4 button is the zero button;
3) Press the K3 key to enter the alarm clock function, after entering, the flashing bit is changeable, press the K2 key to adjust and change the bit, the K3 key is the auto-increase key, and the K4 key is the auto-detract key.
MCU system electrical.
The AT89S51 is available in a 40-pin, dual in-line (DIP) package with the following pin functions: First, VCC—+5V in operation. The second is that XTAL1 is the input of the oscillator inverting amplifier and its internal clock generator. The third is GND—grounding. Fourth, RST- is used to reset the input, and when the crystal oscillator is working, the RST pin is used to act on the high level with more than 2 machine cycles to promote the reset of the microcontroller. This pin is affected by WDT overflow to output high, and can be turned off or on by setting the Disrto bit (address 8EH) of the SFT AUCR. The disrto bit defaults to REST output high on. The fifth is XTAL2, which is the output of the oscillator inverting amplifier. Sixth, there is no self-locking switch (S2 P3.).7) Switch with corresponding pin P37 to connect, press the switch, pin is low 0 when disconnected, pin has high level 1. Sixth, P1 port, P2 port—P1, P2 is an 8-bit bidirectional I-O port with internal pull-up resistor. In the process of operation, the driving circuit is controlled by the P1 port, the data is transmitted to the digital tube, and the corresponding segment code is displayed, so that the power consumption is reduced, and the power consumption is reduced, and the maximum current is limited, and a current limiting resistor is added. p2.0—p2.The 7 ports control the position selection of the digital tube, and then let the data be displayed by the six digital tubes in turn, and when it is 0, the triode is guided to the position selection, and when it is 1, the triode is cut off for the position selection. Seventh, EA VPP, off-chip program memory is accessible to the signal. If the CPU is only accessible to external program memory, the EA must be held low, and if the EA is high, the CPU will execute instructions to the internal program memory.
References. 1] Liu Pengjuan, Yang Bin. Design of multi-channel temperature measurement system based on single-chip microcomputer[J].Electronic Production,2022,30(20):39-41+82
2] Lin Sen, Hu Qing, Wang Yumeng. Design of automatic meteorological monitoring system based on single-chip microcomputer[J].Electronic Components & Information Technology,2022,6(09):35-38
3] Wang Xin, Yu Hao, Zhang Yuting, Jackie Chan, Wang Qing. Design and research of intelligent elevator system based on single-chip microcomputer[J].Internet of Things Technology,2022,12(09):68-69
4] Li Jiaxiang. Design of energy-saving window control system based on single-chip microcomputer[J].Electronic Technology and Software Engineering, 2022(18):66-69
5] Tao Ranting. Design of temperature acquisition system based on LabVIEW and microcontroller[J].Equipment Management and Maintenance,2022(17):128-132
6] Peng Chuang, Yang Yingwen, Yang You. Design of alcohol concentration testing system based on single-chip microcomputer[J].Electronic Technology and Software Engineering, 2022(17):128-131
7] Pan Ting, Long Fanying, Li Hongbo. Research on the design of temperature-controlled water cup based on single-chip microcomputer[J].Science and Technology Innovation and Application,2022,12(24):34-37
8] Xu Min. Design and implementation of buzzer based on STC89C52 microcontroller[J].Wireless Internet Technology,2022,19(16):95-98
9] Yang Zhixia. Design of wireless multi-point temperature monitoring system based on single-chip microcomputer[J].Wireless Internet Technology,2022,19(16):86-88