Design of AT89S51 MCU extended external interrupt source system

AT89S51 provides users with two external interrupt request inputs INT0 (inverse of) and INT1 (inverse of). In the actual application system, the two external interrupt request sources are often insufficient and need to be expanded. The following describes a method to expand external interrupt sources. As shown in the figure below, if there are five […]

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Design of AT89S51 single chip microcomputer and 82c55 interface chip

1. Hardware interface circuit The following figure shows the circuit diagram of an extended 82c55 of AT89S51 single chip microcomputer. In the figure, 74ls373 is an address latch, P0.1 and p0.0 are connected with the address lines A1 and A0 of 82c55 through 74ls373; P0.7 is connected to the chip selection terminal CS via 74ls373, […]

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Introduction to the internal hardware structure and characteristics of AT89S51 single chip microcomputer

The on-chip hardware structure of AT89S51 single chip microcomputer is shown in Figure 2-1. It integrates the basic functional components necessary for control applications on a limited size integrated circuit chip, and has the following functional components and characteristics: (1) 8-bit microprocessor (CPU). (2) Data memory (128B RAM). (3) Program memory (4KB flash ROM). (4) […]

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Design of digital voltmeter based on AT89S51 single chip microcomputer

A digital voltmeter is designed by using single chip microcomputer AT89S51 and ADC0809. It can measure the DC voltage between 0-5V and display it in four digits, but it requires the least number of components. 1. Circuit schematic diagram Figure 1.28.1 2. Hardware connection on the system board a) Connect p1.0-p1.7 in the “single chip […]

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