Method and circuit for protecting single chip microcomputer chip from damage caused by reverse insertion

Abstract

Provided is a method and circuit for protecting a single chip microcomputer chip from damage caused by reverse insertion. A monitor circuit is set which contains a microprocessor master chip U2 for monitoring whether MCS-51 series chips U1 of a single chip microcomputer are reversely inserted in sockets. A transistor Q1 in the monitor circuit is serially connected with an input terminal of a powersupply source Vcc of the single chip microcomputer. The three pins of the chip U1 are electrically coupled to the P1 pins of the master chip U2, respectively; when the single chip microcomputer is powered on, a method 1: detecting that the pin P1.3 of the master chip U2 is at a high level, indicating that the single chip microcomputer is in a reset state and the pin PSEN and ALE of the single chip microcomputer U1 are both at a high level, which are at the normal state; otherwise, if the two pins are at low level, the U1 is inverted, Q1 is transiently switched off, and Vcc is blocked; a method 2: detecting the voltage drop VD-S of the Q1 tube, if it increases abnormally, it is determined that the U1 is inverted, and then Q1 is turned off instantaneously, and Vcc is blocked. The method andcircuit are simple and reliable, which is suitable for 51 series single chip microcomputer teaching and learning.

Description

technical field [0001] The present invention relates to a single-chip microcomputer used as a teaching instrument (hereinafter referred to as "single-chip microcomputer" or "single-chip microcomputer"), especially relates to MCS-51 series single-chip microcomputer, which protects and warns that its chip is inserted upside down during the teaching and learning process. Damage methods and circuits. Background technique [0002] Prior art MCS-51 series single-chip microcomputers are widely used in the intelligent management of instruments and meters, household appliances, medical equipment, aerospace and various special equipment in the electronic control equipment manufacturing industry and in the teaching of colleges and universities and secondary vocational schools, and process control etc. However, when some beginners use the single-chip microcomputer, they often do not know the order of the pin arrangement of the microprocessor (hereinafter referred to as "chip" or "main ...

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Problems solved by technology

However, when some beginners use the single-chip microcomputer, they often do not know the order of pin arrangement of the microprocessor (hereinafter referred to as "chip" or "main chip") installed in the single-chip microcomputer, and it is easy to insert the single-chip microcomputer chip in the reverse direction (hereinafter referred to as "chip" or "main chip"). Referred to as "inverted insertion") into the dual-in-line socket, causing the single-chip microcomputer and its chip circuit to be short-circuited, causing the chip and peripheral circuits to be injured or even damaged

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