is a programmable timing/counter with three 16-bit counters with a counting frequency range of 0-2MHz, powered by a 5V single power supply.
According to the principle of time control, the use of parallel interface and timer, the use of time interrupt to design a set of intersection traffic light management system, traffic time (orDisable time) 30 seconds, the preparation time is 3 seconds, during the preparation time, the yellow light flashes three times, the flashing frequency is 0.5 seconds, and the cycle starts again.
Master: interrupt basic principle, interrupt response, timing, interrupt processing process, interrupt service programming, interrupt vector calculation; 8259A and 8253 operating principles, initialization programming, typical system application, typical schematic connection, circuit analysis, and application program design (8153 in the way of Mode 3,8259 cascades).
A has two address pins A1 and A0 for on-chip address decoding, and A1A0 should be connected systematicallyThe process is made of programmable counter/timer, there are several chip models, shape pins and functions are compatible, but the maximum count rate is different, such as 8253 (6MHz), 8253-5 (5MHz).
2, in seconds, clk=91MHZ can be understood as the frequency of clk, then 91M is the total length of the distance of clk in one second, and the number of square waves generated by 25KHZ is 25K in one second. In this case, the value obtained by using 91M/25K is a period length of the square wave. This length is the initial value of OUT. <3, the clock input frequency of the counter is 91MHz, then the pulse period of the counting clock is 1/ (91M) seconds. Output 25KHz square wave output signal, using mode 3. The period of the square wave is 1/ (25K) second.
4. Set the port address of 8253 to 340H to 343H (the address of counter 0 is 340H, and the address of control port is 343H). Known counter 0 CLK0 input clock signal is 1MHz, OUT0 continuous output 50KHz square wave, please fill in the blank to complete the following program segment, the counting mode is binary.
5, set the input clock frequency to 100 KHz) Design a square wave pulse generator with an output frequency of 20KHZ with 8253 counter 0, if the input clock frequency of the counter is 4MHZ, the gate address of 8253 is 240H-243H, and BCD counting is used. (1) The initial value of the count is required to be calculated, and (2) the initialization program is written.
1, At89S8253, is ATMEL's AT89S series of upgraded chips were the best of the year. But that was over a decade ago. Mainly more EEPROM than AT89S53, which was worth showing off in the year. However, few people use it in China, and the most popular is AT89S51.
2, hello! It is recommended to use STC, both of which are 51 core single-chip computers, the program is basically universal, but the program download method, processing speed and part of the expansion function are different, compared to STC15 series is better if you have questions, please ask.
3, AVR MCU, PICAT89S825AT89S8253 and so on, a lot of ah! STC MCU is not EEPROM at all, the real EEPROM supports byte programming, STC is only part of the program memory.
4, the volume of the single chip is relatively small, the internal chip as a computer system, its structure is simple, but the function is perfect, the use is very convenient, can be modular application. (2) The single chip microcomputer has a high degree of integration and strong reliability, even if the single chip microcomputer is in a long time of work, there will be no fault.
5, STC is 51, ATMEDG is AVR, generally so, but if there are more chips, look at the model is not visible, 51 and AVR refers to the core of the MCU is 51 or AVR.
6, the advantage is to realize the control function at the same time has a stronger data processing ability, a powerful network communication function and the ability to perform more complex control algorithms and its almost unlimited storage capacity and other advantages. The disadvantage is poor stability, easy to be disturbed, programming and maintenance are more difficult.