在嘈杂的环境中通过USB与其他设备通信时，PC USB主机失败(EMC/EMI测试) [英] PC USB host failed when communicating with other device through USB in noisy enviornment (EMC/EMI Test)

问题描述

设置-硬件将USB设备连接到PC主机. PC和硬件之间的某些数据传输(发送和接收)可以通过使用USB通信的应用软件来完成.在台式测试中没有出现问题(意味着没有任何嘈杂的环境，即处于理想状态)，但是在嘈杂的环境中发生了问题(出于测试目的，通过连接到硬件和PC的USB电缆有力地产生了噪音).

状态-没有通过硬件和PC的通信，只需将USB电缆连接到硬件和PC，然后通过USB电缆产生噪音.噪声测试完成后，尝试使用应用程序软件进行通讯，但未建立通信.

观察-数据已被应用程序软件发送但无法接收(如USB调试软件所示).同样，硬件也没有收到接收数据的中断.因此，问题出在设备驱动程序还是硬件上.但是硬件通过使用设备和硬件主机的回送测试进行了测试.硬件主机与设备之间的测试行为相同，并且可以正常工作.因此，在PC端(在设备驱动程序中)查找问题.

Setup - Hardware have USB device connected to PC host. Some Data trasfer (send and receive) between PC and Hardware can be done through application software using USB communication. No problem occured at table test (means without any nosiy envoirnment i.e. in ideal condition) but problem occured in noisy envoirnment (for testing purpose forcefully create the noise through USB cable to hardware and PC).

Condition - No communication through hardware and PC just connect USB cable to hardware and PC then create noise through USB cable. After noise test finish try to communicate using application s/w but no communaction established.

observation - Data are send but could not receive by application s/w (shown on USB debugging s/w). Also Hardware did not get interrupt to receive data. So whether problem is in device driver or hardware. but hardware is tested by loopback test using device and host of hardware. Same test conduct between hardware host and device and it works. So problem looking in PC side (in device driver).

推荐答案

在测试环境中一切正常吗?

如果是这种情况，那么问题可能与通讯媒体，无线电或电缆有关?

电缆可以屏蔽，无线电是一个众所周知的问题"，使用工业级设备可以轻松解决，但通常价格更高.

根据环境的不同，您可能也必须屏蔽计算机内部的组件.

除非您要交付大量设备/个人电脑，否则通常最好购买已经针对目标环境进行了认证的设备.

祝你好运

问候
Espen Harlinn

Everything works in test envirenment?

If that''s the case then the problem is probably related to communication media, radio or cable?

Cable can be shielded, radio is a "well known problem", easily solved by using industrial grade equipment, but usually way more expensive.

Depending on the envirenment you may have to shield components inside the computer too...

Unless you are to deliver a huge amount of devices/pc''s it''s usually best to buy equipment allready certified for the target environment.

Best of luck

Regards
Espen Harlinn

EMC测试是一个真正的痛苦！

如果您的外部硬件(在USB电缆的末端)崩溃了，并且没有看门狗或类似的复位设备，那么我认为在PC端您几乎无能为力.如果它由USB供电，则可能可以断开电源并引起复位，但是恐怕我不知道该如何在软件中执行此操作.我看到您说数据已发送但未收到，这些看起来很奇怪.

首先考虑防止噪声引起问题可能是有用的.我发现接地在EMC中非常重要，值得尝试将电缆的一端或另一端或两端都接地，以查看最有效的方法.我想硬件还没有买进，或者您不必对它进行EMC测试，因此您应该可以在某种程度上尝试一下.您也可以尝试以某种方式屏蔽电缆.我们经常在电缆周围使用铁氧体磁珠，但我从未在USB电缆上尝试过此方法.

最后一件事，很可能是在EMC测试期间，您的软件将收到各种非法值，因此请仔细检查它们是否都得到了正确处理，这不仅是因为您的应用程序在某个时候被卡住了"，还在等待数据.永远不会到来.

祝您好运:)

Hi,

EMC Testing is a real pain!

If your external hardware (at the end of your USB cable) has crashed and has no watchdog or similar to reset, I think there is little you can do at the PC end. If it is powered by the USB then it maybe be possible to remove the power and cause a reset, but I am afraid I don''t know how to do this in software. I see you say that data was sent but not received, these seems odd.

It maybe usefull to look at preventing the noise from causing a problem in the first place. I have found that earthing is very important in EMC and it is worth trying to earth the cables at one end or the other or both and see what works best. I guess the hardware is not bought in, or you would not have to EMC test it, so you should be able to try this to some extent. You could also try to screen the cable in some way. We often use ferrite beads around the cables but I have never tried this on a USB cable.

One last thing, it is likely that during the EMC test your software will receive various illegal values so double check that they are all being handled correctly and it is not just that your application gets ''stuck'' at some point, waiting for data that will never arrive.

Best of Luck :)

更新-问题已解决

这是USB硬件问题.噪声滤波器(共模扼流圈)在USB硬件中实现.

Update - Issue has solved

This was USB hardware issue. Noise filter (common mode choke) is implemented in USB hardware.

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