On the discrimination of "fake death" state of STC single chip microcomputer

About STC Single chip microcomputer “ Feign death ” State discrimination

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• Declare that this is not laihei STC Single chip microcomputer .

I found out in the process of testing the program today , my STC8G2K64S4 The development board suddenly cannot burn the program , Just burned everything normal , Suddenly, I can't burn into the program , Serial port can recognize , adopt ISP No matter the board is cold started, the software can't detect the MCU , There are serial port numbers , SCM can't be so weak to sacrifice , There is no physical operation , Burning a program can also burn out the single-chip microcomputer, which will not .

Open today STC-ISP Burn Software , Prompt for a new version , Upgraded version v6.90

Cause analysis

As for why STC ISP The software cannot recognize the chip , Here is my personal view ：

1. stay IO Mouth operation , The external crystal oscillator pin is used as the input or output pin , Try to avoid using crystal oscillator pins in the development process of single chip microcomputer , Here, only the external crystal oscillator is used , Because some models provide crystal oscillator internally .
2. It is indeed. STC ISP The tool has the following options .

STC-ISPV6.88J edition , Old edition

• stc-isp-v6.90 edition , At present, the latest , The first embarrassing thing I encountered .

stay stc-isp-v6.90 edition , The choice is STC8G2K64S4, I'm sure it's impossible for me to check the above options , Because I have encountered this situation before , The download time is right “ At the next cold start ,P3.2/P3.3 by 0/0 Before downloading the program ”, Because I burned the program several times before , It's a sudden fake death , Unrecognized situation .

First of all, I want to correct STC-ISP A mistake here ：“ At the next cold start ,P3.2/P3.3 by 0/0 Before downloading the program ” It should actually be ： Want to 89 The model of single chip microcomputer is the same ,“ At the next cold start ,P1.0/P1.1 by 0/0 Before downloading the program ”. As for why I can find this problem , I also thank myself for recording some mining experience .

Last year, I published an article about STC Burning articles ;

• 《STC Don't step on the pit burned by the single chip microcomputer 》

See this picture in this article ：

Trying to follow STC-ISP Corresponding model “ At the next cold start ,P3.2/P3.3 by 0/0 Before downloading the program ”, Option operation did not succeed , Just try to use the previous “ At the next cold start ,P1.0/P1.1 by 0/0 Before downloading the program ” Follow this connection , Click detection MCU, Immediately see the serial port Indicator Flashing , And successfully detected the single-chip microcomputer model .

SCM fake death judgment

If you know what program is burned in the MCU , If there is IO Mouth state , You can measure the corresponding IO Whether the mouth state is normal . If IO normal , It is certain that the SCM is not broken , It's just ISP The single chip microcomputer cannot be detected .