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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).
Posted 10-Jan-11 18:40pm
Comments 11-Jan-11 8:08am
Is there a question here?
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Solution 1

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

Espen Harlinn
pravin29 12-Jan-11 0:03am
Everything works in ideal condition.
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Solution 2


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 :)
pravin29 11-Jan-11 23:58pm
Right now just consider s/w has no role during noise test. After finishing noise test i tried to communicate with device and device gets connected. Send the data but could not receive. So will software or driver need some care?
Alison P 12-Jan-11 4:33am
Do you mean that you send the data from the PC end and it is not received by the device or that you send the data from the device and the PC does not receive it? Even if the software has 'no role' during test if it is running could noise create data input that 'looks like' data but is in fact invalid? Can you run the software app. in debug mode during the test, that might help you to figure out where the problem lies. Best of Luck. :)
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Solution 3

Update - Issue has solved

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

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