Let's talk about MCU crash caused by hardware problems

About MCU Crash problem , Recently, Xiaobian encountered many cases during his business trip , And for different reasons . therefore , Today, Xiaobai takes this opportunity to talk about the hardware problems MCU crash .

MCU Bad

In case of a crash , It can be determined that it is caused by hardware , Most people choose cross validation MCU, First determine whether it is MCU Crash caused by bad monomer . In the process of handling the crash problem encountered by Xiaobian before , because MCU Crash caused by poor performance , Not much , But it is also true that there are such reasons .

The power supply is abnormal

About the abnormal power supply MCU crash , In fact, it is also the most common . I have encountered too many crash problems caused by abnormal power supply during my business trip to the factory production line .

Inexperienced hardware engineer , Encounter this kind of problem often have no way to start . Anxious people tend to follow the first reason above , Replace first MCU, If it still exists, replace it PMU, If... Is used in the circuit Memory, I believe it will also be replaced . If it is really caused by these three factors, it may be OK , But once it is not these three factors that lead to , We also need to relocate and troubleshoot .PMU Troubleshooting of output voltage , It should be the first step in the follow-up investigation .

Xiaobian once went on a business trip in the production line , Encountered a cause PMU Crash caused by abnormal power supply , Later, it was investigated step by step , Find out PMU The chip polarity of the later stage load chip is reversed , take PMU The relevant power supply is pulled down , Affect the stability of power supply , And then cause the crash problem . When we put the later stage load chip according to the polarity requirements , Realign , The crash problem will no longer occur .

The crystal oscillator circuit is abnormal

It is said that crystal oscillator belongs to electronic products “ Great heart ”, It's security MCU One of the orderly operating conditions , by MCU Provide clock frequency , Very stable . However, once the crystal oscillator body fails or the related circuit wiring is disturbed , It's all possible to cause MCU crash . For the problems of crystal oscillator , We can often get close to MCU End measurement clock frequency , To determine whether the measured value conforms to the design standard , Whether the measured value is stable .

Electrostatic introduction

About the crash caused by static electricity , It is often an illusory existence . In previous projects , The production test has a very low probability of crash , Software capture log, It is often impossible to see the root cause . At the same time that the root cause cannot be seen , Most people also like to talk about static electricity . The chip is unstable or poor due to static electricity , It often becomes the reason why many chip manufacturers reply to customers that their chips are defective .
although , however ！
But some problems are caused by static electricity . At this time , We can use the electrostatic gun to conduct contact discharge test at the sensitive position to simulate the crash phenomenon . The crash caused by the introduction of static electricity , We just need to follow the solution ESD To solve the problem .

Power supply interference

In some high frequency circuits , Its radiation and other interference will affect the stability of the power supply , This is the case , It can also cause a crash . The best solution is , High frequency circuit wiring shall avoid power wiring as far as possible .

besides , There are more than these reasons for the hardware crash , Unexpected short circuit caused by poor patch or assembly in the circuit can sometimes lead to crash , When doing mobile phone projects , Some employees were assembling the main and auxiliary plates FPC when , Not in strict accordance with SOP Homework , It leads to poor assembly, which causes the mobile phone to start and enter dump Pattern , The machine restarts repeatedly . Finally, it was found that the machine was disassembled and checked BTB The short circuit is caused by the deformation of the seat , To find out why .