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Multilink USB JTAG/ONCE issue
Victor M. Oct 9, 2014 at 08:25 AM (08:25 hours)
Staff: Takao Y.

  • Hello,

    I'm attempting to communicate with a MPC5566 via JTAG but am having trouble connecting. The error I am running into is: error in ONCE status register during instruction execution. This error repeats multiple times until some sort of connection is established. Once I am somewhat connected, I am unable to see anything as everything read as a Bus Error - No Opcode or change values within the general purpose registers. I have attached an image that shows what my issue is in ICDPPCNEXUS and PROGPPCNEXUS. I am using the 64k Starter Edition debugger version Do i have to use the JTAG to set the ONCE status register? Any help is appreciated.




  • Greetings,

    This is not an issue on the software but something is wrong with your hardware setup. Something is preventing the software to read the ONCE status registers needed for flash programming and debugging.

    Some questions:

    1) Is this your first attempt with the P&E software and hardware tools or has this setup worked in the past?

    2) Do you have any custom ribbon cables, adapters, external watchdog, or other reset circuitry in your hardware setup?

    3) Double check your connections. Do you have all the pins connected? Or are you omitting signals like VDD or GND?

    You should not need to do anything special to get this working.

    Takao Yamada

    • Hi Takao,

      The issue was due to the MPC5566 being held in reset and I was able to resolve this issue, thanks for the help. I was aware that this was most likely a hardware issue, but wasn't sure where to ask. I posted a similar question on freescales website, but I noticed you guys were better at answering in a timely matter.

      As of now I can establish a connection. To answer your questions:

      1. Yes, this is my first time using P&E software and hardware tools.

      2. I do have a custom setup.

      3. One of the reset pins was incorrectly connected.

      Since I am unfamiliar with the P&E software tools, could you refer me to documentation that would assist with understanding the tool?

      Thanks for your help!

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