Board cannot boot when signal is present

[michaeldkfowler]

I have an mimxrt105-evkb rev a1 that I have installed the 0 ohm resistors on to enable using SPI from the Arduino headers. If I plug a signal generator into any of the Arduino header pins, the board will load into bootloader mode as if the reset button is held down while inserting the USB cable. Why would this happen? The board boots fine if nothing is plugged into the headers.

[jeremyzhou]

Hi @michaeldkfowler ,
Thank you for your interest in NXP Semiconductor products and for the opportunity to serve you.
I think you'd better introduce the testing environment in detail, especially, the hardware modifications you did.
Have a great day,
TIC

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[michaeldkfowler]

Hi Jeremy,
I added a 0 ohm resistor to R278, R279, R280, and R281.

[jeremyzhou]

Hi，
Thanks for your reply.
Firstly, the weld these above 0Ω resistors won't affect the boot-up, next, you'd better follow the readme of evkbimxrt1050_lpspi_interrupt_b2b_master demo to test the LPSPI module.
Have a great day,
TIC

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[michaeldkfowler]

Hi Jeremy,

 My issue has nothing to do with SPI. As I said, my issue is, the board will not boot when there is a signal generator connected to any pin on the arduino header.

[jeremyzhou]

Hi @michaeldkfowler ,
Thanks for your information, even if it seems a bit weird.
To be prudent, I was wondering if you can illustrate the steps of replicating the phenomenon, for instance, how to connect a signal generator and what kind of signal you select, etc, as I'd like to replicate it on my board.
Have a great day,
TIC

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[michaeldkfowler]

Hi Jeremy,

 I connected a signal generator with a square wave at 0-3.3v to any pin on J22, J24 or J23 to encounter the problem.

[jeremyzhou]

Hi @michaeldkfowler ,
Thanks for your reply.
I don't have a signal generator on hand, so I use a MIMXRT1170 board to generate the square wave to simulate it, you can see the wave below figure, further, I connect the wave to the J24-4 pin or other J24 pins, actually, it doesn't affect the boot-up process.

Have a great day,
TIC

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[michaeldkfowler]

Thanks Jeremy,

 Did you try plugging in the USB cable after starting the signal generator? When I do, the built in debugger boots into bootloader mode.

[jeremyzhou]

Hi @michaeldkfowler ,
Sorry for replying late, as I was not at the office since Thursday in last week.
Whether you mean the MIMXRT1170 board as the signal generator generates the square wave output to the MIMXRT1050 board, then plugging the USB cable to the MIMXRT1050 board, as the below shows.

Have a great day,
TIC

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[michaeldkfowler]

yes

[jeremyzhou]

Hi,
After several rounds of testing, the MIMXRT1050 still can boot up successfully, even though plugging in the USB cable after starting the signal generator.
Have a great day,
TIC

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Have a great day,
TIC

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