1, RST input has two functions. First, the RST switches on the control logic, allowing the address/command sequence to be fed into the shift register; Second, RST provides a means of terminating the transmission of single byte or multi-byte data. When RST is high, all data transfers are initialized to allow for DS1302 Perform operations. If RST is set to a low level during transfer, the data transfer is terminated and the I/O pin changes to a high resistance state.
2, CD4511 has 4 inputs, 8 outputs, 4 input high and low levels constitute different sizes of 4-bit binary number, on the other end of the 8 outputs on the digital tube, the digital tube will display a hexadecimal number, to achieve the effect of translation and drive.
3, DS1302 used, very inaccurate, depending on the external capacitance, not good to tune, sometimes a day can be different for a few minutes, can only use software correction, very numbBother. DS3231 is good, only one or two minutes a year, the circuit connection is very simple, very easy to use.
4, the crystal oscillator circuit is the clock circuit in the smallest system, which provides the time benchmark for the MCU. When the MCU works, it takes instructions from the ROM one by one and then executes them step by step. How often to execute an instruction, which requires a time benchmark, so that the basic functions of the single chip computer program to be realized. The crystal oscillator circuit is used to provide this time reference.
5, DS1302 serial communication interface is neither standard SPI, norIt's not an IIC, it's a simple three-wire bus.
6, DS1302 is a clock chip, produces standard clock data, and is not a timer, so it can only be timed according to the clock, not timing. To timing, use the MCU according to the time of DS1302, by timing start time, end time to judge, to achieve timing. For example, if the timing is 10 minutes, you can set the start time at 9 o 'clock and the end time at 9:10 o 'clock.
DS1302 used the programmable clock chip , very inaccurate Programmable clock chip , depending on the external capacitance, it is not easy to adjust, sometimes a few minutes a day can be different, can only use software correction, very troublesome. DS3231 is good, only one or two minutes a year, the circuit connection is very simple, very easy to use.
Timing accuracy is the most key to the crystal oscillator, the crystal oscillator with the single chip computer is very roughRough, used to complete simple timing tasks with low precision. To implement the clock must be very wrong. DS1302 is a special clock chip produced by the old United States, which is specially used for clock circuits, and the accuracy is definitely not the same. In addition, it is extremely convenient to use, no longer use timers to achieve interrupt timing, only simple reading can be done.
DS1302 Contents 1 Abstract 1 Introduction 2 DS1302 structure and working principle 3 DS1302 real-time display time hardware and software 4 Problem description in debugging 5 Conclusions [edit this paragraph]1 Abstract introduction of the United States DThe structure, working principle and application in real-time display time of DS1302, a low power real-time clock circuit with trickle current charging capability, introduced by ALLAS.
DS1302 Programmable clock chip : This is a classic RTC chip, with low power consumption, multi-year life, and high precision. The price in the market is generally around 1 yuan. PCF8563: This is an RTC chip suitable for anniversaries, alarm clocks, timers and other applications, with high time accuracy, small size, low price and other characteristics.
887, this is a parallel port output, has its own internal battery, even if the external power off can work for a few years, the price is very expensive, of course, it is very much compared with its programmable clock chip , the price is more than 10 pieces, and the volume is very large. 1302 is the most used, the price is cheap, the price is about 1 piece, the use of serial communication, small size, no internal power supply and crystal vibration, the need for external connection.MCU timer uses its own crystal oscillator, not specially used to do electronic clock, because its accuracy is not high, and operationMake trouble! And to correct a point, DS1302 is not used for timing, it is a clock chip, there is a special register inside for storing the year, month, day, minute and second, the crystal oscillator is also connected to another, high precision.
PCF8563 has three chips: PCF8563P, PCF8563T, and PCF8563TS. PCF8563 has two types of encapsulation, of which the T suffix is SOIC-8 encapsulation, with suffixP is DIP-8 package. Its pin functions are as follows.
Overview The PCF8563 is a low power CMOS real-time clock/calendar chip that provides a programmable clock output, an interrupt output, and a power down detector, with all addresses and data passed serially through the I2C bus interface. The maximum bus speed is 400Kbits/s, and the embedded word address register automatically generates increments after each read/write.This chip parameter is BS27 package, operating voltage from 6V to 18V, 4x25W output power (14V, 10)>
RX8025, PCF8563. RX8025 million calendar chip, with USB charging, PM2 point 5 sensor interface, SHT20 temperature and humidity sensor interface, infrared receiving interface, etc. PCF8563 is a low power consumption CMOS calendar chip, providing 1 programmable clock output, 1 interrupt output and power failure detector. All addresses and data are passed serially through the I2C bus interface.
Can be used AT89S52 MCU DS1302 oscillating IC LCD, as shown in picture 1, can also be used perpetual calendar IC provider ICTo do it. There are many options. Using the perpetual calendar IC manufacturer's program, the cost will be much lower, reduce the development time, reduce the development cycle, just need to get back, cloth a PCB board, do an LCD or design an LED driver circuit.
Yes. TG1508 is only the digital calendar inside the time control chip, it controls the digital calendar time, date, week, temperature and other information setting and operation, and time, date, week, temperature is displayed through the LED digital tube. The perpetual calendar is the oldest solar calendar in ancient Chinese legend. The name of the perpetual calendar is derived from the quotientTo a man named Ten thousand, who was the compiler of this calendar.
1, mainly highlight the count and carry, omit the preset and calibration, and simplify the seven-segment code display circuit.
2, clock circuit principle -- pin real-time clock circuit DS1302 including VCCVCCXXSCLK, I/O, RST, GND eight pins.
3, the internal clock schematic (is a self-excited oscillation circuitIn the internal mode clock circuit, the quartz crystal oscillator and two fine tuning capacitors must be connected at both ends of the XTAL1 and XTAL2 pins to form an oscillation circuit, usually C1 and C2 generally take 30pF, and the frequency of the crystal oscillator is between 2MHz and 12MHz.
4, ①② step more intuitive status diagram is as follows. The counter requires 3 JK triggers, labeled JK1/JK2/JK Step 3 Carnaugh diagram simplification Take J2 as an example, other values are similar, J2 Carnot diagram: that is, J2=BC=Q1Q0, so simple and gate can be achieved.
Cost is different, precision is different. The DS3231M is low cost and high precision. The DS1337 has low power consumption. The DS3231M is a low-cost, high-precision I2C real-time clock (RTC). The device includes a battery input that maintains accurate timing when the main power supply is disconnected. Integrated microelectromechanical systems (MEMS) improve the long-term accuracy of devices and reduce the number of components in the production line. The DS3231M is the same as the popular DS3231RTCDevice packaging.