RT1020 can not debug from mcuxpresso

dani-tse — Thu, 26 Feb 2026 05:45:29 GMT

I'm working on a project based on mimxrt1021CAG4B using a custom board. I tried one of the demos in mcuxpresso, after successfully flashing it using jflash the mcu is not leaving serial downoader mode. I then configured the project to link to ram instead of external flash, this time I can run and debug the program from mcuxpresso, but when I configure the project to link to flash I can not debug or run from mcuxpresso. As a final test I used mcu boot utility to flash the program(linked to flash not ram) and this time the mcu is able to execute code from flash(xip). It turns out mcu boot utility is changing the first 8k of my program with values that I don't know how it came to modify them. it's changing the boot config data, part of the IVT, boot data and almost entire DCD section. If the only way to execute from flash is by letting mcu boot utility change the first 8k of my program, then why bother having it the possiblity to edit those value in mcuxpresso? I am talking about the following variables:

const flexspi_nor_config_t qspiflash_config

const ivt image_vector_table
const BOOT_DATA_T g_boot_data

Re: RT1020 can not debug from mcuxpresso

mayliu1 — Thu, 26 Feb 2026 10:20:47 GMT

Hi @dani-tse ,

Thank you so much for your interest in our products and for using our community.

1. Why it worked with MCUBootUtility
MCUBootUtility generates and inserts the required FlexSPI NOR boot header (FDCB, IVT, Boot Data, ....) at the beginning of the flash image. This allows the ROM to correctly initialize the external flash and boot your application.

2. Why it worked in RAM but not in Flash
When you link the project to RAM, the debugger simply loads your code into on‑chip SRAM and runs it.
For this mode, FlexSPI NOR initialize by the ROM is not required, so your application code can run even without a valid flash boot header.

However, when the image is linked to Flash, the ROM must read a valid FDCB/IVT header first.
If the header is missing or incorrect, the ROM cannot initialize the flash and will enter Serial Downloader mode.

3. Recommended fastest method to enable XIP flash debugging on RT1020
The quickest and most reliable approach is to import an existing RT1020 SDK XIP demo and modify it.
If you are using a different flash device, adjust the flexspi_nor_config_t accordingly.
Please pay special attention to the LUT tables, since incorrect LUT settings are one of the most common causes of XIP boot failures.

Wish it helps you

Best Regards

MayLiu

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RT1020 can not debug from mcuxpresso

Re: RT1020 can not debug from mcuxpresso