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LAUNCHXL2-TMS57012: Using launchpad to debug an external MCU

Guilherme Pissaia
Prodigy 40 points
Part Number: LAUNCHXL2-TMS57012
Other Parts Discussed in Thread: TMS570LS1224

Hello team,

My case is: I have a LAUNCHXL2-TMS57012 and I'm designing a prototype where I use the same MCU as the launchpad (TMS570LS1224).
My idea is to use the launchpad to debug the MCU in my prototype. I would connect my computer to the launchpad via USB, and the launchpad to my PCB through J1 connector, following the steps:
- Place J1 connector on the launchpad
- Supply the launchpad with 5V and GND coming from my PCB
- On my PCB, place a connector to receive the launchpad's J1 signals
- Route these signals to my PCB's MCU, in the same way as it is in the launchpad

From what I see, I would upload the CCS project to both MCUs. But, as I will not use the one at the launchpad, I does not matter. I think whthat I might have a problem while running the program while the boards are connected, but after I separate them, it should work normally, would it?
Is this going to work? Is there any other precaution that I need to have in this process?


Thanks in advance,

Guilherme Pissaia

  • 0
    TI__Mastermind 46535 points

    Hi Guilherme Pissaia,

    This is not ideal way to do because:

    You can short the input lines of two controllers, but you cannot short the output lines. I mean you can short the TCK, TMS and TDI of two controllers but you can not short the TDO of two controllers because this will lead to data corruption. The both controllers may not put same data all the time right, if one controller try to set the line and other controller try to reset the line then the result would be logic-0 and the controller which want to set the line will end up with data corruption.

    And i just found that JTAG chaining would also not possible from below thread

    TMS570LC4357: Uniflash & JTAG chain - Arm-based microcontrollers forum - Arm-based microcontrollers - TI E2E support forums

    If JTAG chaining supports then we can connect the devices as below:

    --

    Thanks & regards,
    Jagadish.

  • 0 in reply to jagadish gundavarapu
    Prodigy 40 points

    Hello Jagadish,

    Thanks for your reply, but having in mind that "do not care" for the launchpad's MCU, I believe that this issue may be simpler than what you explained.

    My goal is to not place a USB to JTAG circuit at my prototype, that's why I am considering the use of the launchpad at the middle. So, considering that I do not want to debug the launchpad's controller, just the one at my PCB, removing the controller from the launchpad and taking all the J1 traces to my PCB would make it work, right? 

  • 0 in reply to Guilherme Pissaia
    Guru 92251 points
    Guilherme Pissaia said:
    So, considering that I do not want to debug the launchpad's controller, just the one at my PCB, removing the controller from the launchpad and taking all the J1 traces to my PCB would make it work, right? 

    Would it be simpler to fit a JTAG connector on your prototype and use a standalone XDS110 JTAG Debug Probe rather than modifying the launchpad to use the on-board XDS110 on the launchpad?

  • +1 in reply to Chester Gillon
    TI__Mastermind 46535 points

    Chester,

    Guilherme Pissaia said:
    just the one at my PCB, removing the controller from the launchpad and taking all the J1 traces to my PCB would make it work, right? 

    If you remove the controller in launchpad then i don't think there would be any issues, it will work.

    Chester Gillon said:
    Would it be simpler to fit a JTAG connector on your prototype and use a standalone XDS110 JTAG Debug Probe rather than modifying the launchpad to use the on-board XDS110 on the launchpad?

    As Chester suggested you can go for standalone XDS110 JTAG probe right?

    --
    Thanks & regards,
    Jagadish.

  • 0 in reply to jagadish gundavarapu
    Prodigy 40 points

    Chester and Jagadish,

    Yes, I could use a XDS110 JTAG Debug Probe, but primarily I would like to use the materials that I already have in the lab.

    This way, at first, probably I will try removing the controller and using the launchpad. In the design itself, I will probably let both circuits ready to use.

    Thanks for your support and best regards.