USB Tap noise sensitivity

[Oppie]

We were having several problems with a spontaneous target reset or loss of communication between the target and USB Tap when debugging a DSP56F8357. This became very obvious when we had one engineer performing ESD (electro-static discharge) testing on a system across the room from another engineer debugging with a USB TAP.  Quite often, on a discharge event, the target system would reset. Very strange since the two projects were on different benches and served by different electrical systems.

By adding a ground lug to the USB tap case and connecting it with a faston terminal and 18AWG wire to the target earth ground, all the reset and communication problems went away. We were shooting 10KV sparks repetitively to a system in close proximity (that would have made Marconi proud) with no USB Tap problems. Before the addition of case ground, even 4KV would cause problems from a further distance.

This would suggest that something is either weakly terminated or floating inside the Tap's case or that the case itself is not grounded to anything internal.

[trytohelp]

Hi,

I suggest you to log your request to the Freescale CRM system.
Please use Freescale on line support web page.
  - Go to following URL: http://www.freescale.com/TechSupport
  - Click on Submit a Service Request to create a new one or Manage Existing Service Request.
  - You will come to a login page.
  - You can submit your request through the web from there or view the activities of a SR.

We should contact the development team regarding this USBTap question.

Regards

Pascal