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IWR6843ISK: MMWAVEICBOOST strange behavior

Maximilien B
Prodigy 115 points
Part Number: IWR6843ISK
Other Parts Discussed in Thread: MMWAVEICBOOST, , IWR6843, UNIFLASH, IWR6843LEVM, IWR6843AOP

I'm used to debugging IWR6843ISK with MMWAVEICBOOST, but I've encountered extremely strange behavior since this morning.

The setup was not touched since yesterday (when debugging was working perfectly fine, including many resets using the button). I did not change any physical setting when it happened, only the code dynamically loaded into the ISK's RAM via CCS debugging. At some point, the XDS110 probe could no longer connect to the IWR6843. I started investigating, and now I have a somewhat clear definition of what happens :

  • When the ISK has just been flashed directly using its own USB connector (away from MMWAVEICBOOST board), it's booting perfectly fine (for example, using some demo and UARTs)
  • From this situation, I plug in the MMWAVEICBOOST (while setting the right switches on both boards), it works fine the first time (be it via JTAG when ccsdebug is flashed, or via UART when a CLI demo is flashed)
  • Then, if I power cycle the ISK (either completely removing the power from MMWAVEICBOOST, or using any of the reset buttons), the ISK board no longer works : no UART output (when a demo is in flash), no JTAG connection (when the debug code is in flash). It also cannot be flashed via the BOOST board anymore (which I was very used to doing, using the SOP2 MMWAVEICBOOST jumper). Sometimes, getting to this broken state takes 2-3 power cycles / resets but generally one of either is enough.
  • If I then remove the ISK from the BOOST, it works again just fine (at least demos via UART, since I can't test JTAG without BOOST).
  • If I then plug the ISK back on the BOOST, it still does not work. The only way to make it work again is to completely reflash the ISK (without the BOOST board).

This seems extremely weird to me. It means that :

  • In some way, booting or rebooting on the BOOST board affects the next reboots in a durable way (i.e. even after powering off everything)
  • This broken state prevents the ISK from functioning ONLY when plugged in to the BOOST board (be it via JTAG or UART if a demo is loaded in flash)
  • The only way to get out of this state is to flash the board again, externally using Uniflash.

The ISK is rev. D from a few years ago, while the BOOST board was purchased from TI a month ago. (Because of this problem I just placed an extra order for a new BOOST and a new IWR6843LEVM boards).

Has anyone encountered a similar situation ? Is it maybe a known issue, or if not how could I investigate it further ?

  • 0
    TI__Expert 4448 points

    Hi,

    This is not a known issue as far as we are aware. So this behavior was not present at any time prior and it just arose today? 

    Regards,

    Luke

  • 0 in reply to Luke Rouleau
    Prodigy 115 points

    I have worked full time on this setup for two whole days, including many resets and power cycles, and it first appeared this morning. Now it's fully reproductible as the post says.

    The only minor update that I have is that it only happens when resetting the ISK (through buttons) or power cycling the board in less than a few seconds. If I wait about 30 seconds or more while the board is powered down, it does not happen. It means the way to reproduce it is to reboot the 6843 on a BOOST board which has power or recently had power.

    Once the bug has happened once, even waiting 30 seconds power off does not work, and the only solution is to unmount and flash.

    I should also add that it does not happen with another IWR6843AOP board I tested (using the same BOOST).

  • 0
    Prodigy 115 points

    Now I can't make the ISK work at all. It still works fine in standalone mode but whenever connected to the BOOST board it no longer functions.

    I have tried with the new LEVM purchased on Friday, everything works perfectly.

    I'm really afraid to burn other boards using MMWAVEICBOOST. I will now always use a USB isolator and a lab grade power supply in order to avoid any problem. I have two more questions:

    • Apart from changing the EVM, is it also a good idea to use the brand new MMWAVEICBOOST (perhaps the old one, although recent, is defective and burns EVMs ?)
    • Would it be useful to send back the ISK (or perhaps both boards) for analysis in order to investigate a possible design issue with the two boards together ?