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TMS320F28379D: EMI JTAG

Renato Amorim Torres
Intellectual 260 points
Part Number: TMS320F28379D
Other Parts Discussed in Thread: TMDSEMU110-U

Hello everyone,

I am trying to shrink the size of my prototype as much as possible. Therefore, I decided to use an external XDS JTAG emulator to communicate with my TMS320F28379D controller.

However, I am concerned about the IDC cable that connects the XDS emulator to my prototype JTAG connector. I have the feeling that this cable is very susceptible to electromagnetic interference (EMI). This can really problematic to me since I need to be constantly connected to the controller that is located in a quite noisy environment (high-frequency inverter). I wonder if there is a better approach than using this IDC cable, but it still needs to be a compact solution.

I was wondering, for example, if I could use the JTAG communication, but instead of using IDC cable I would use some sort of twisted shielded cable, where every signal is twisted with a ground. 

I would appreciate any suggestions or comments.

Renato

  • 0
    TI__Guru**** 171309 points

    Renato,

    The TMDSEMU110-U was fully tested for immunity (EMC) according to EN61326-1:2013 (IEC/EN61000-4-2, IEC/EN61000-4-3 and IEC/EN61000-4-8).

    In practice, this translates to a very reasonable reliability in noisy environments using the provided cables, as long as the connections are kept short and any ground loops are avoided, either by galvanic isolation or by floating one of the ends of the connection. However, this is obviously highly dependent on the environment and intensity of the EMF and surely the communications may break down in face of strong fields.

    In case of EMF, you can try to shield the cable in its entirely (a grounded copper foil tape may help) or try the twisted cable - I personally never tried any of the methods, but the twisted pair cable may not bring too much improvement since the 20-pin IDC cable already has pins 8, 10, 12, 16 and 20 already grounded. 

    In case connections are lost, I would also trim the TCLK speed (default can be 2.5MHz, 5.5MHz or 8.5MHz depending on the CCS version) - the added ground will increase the capacitance on the lines, although perhaps very marginally. 

     

    Hope this helps,

    Rafael