Tips in getting into ARM Cortex M7 processors and external memory (imxRT1020)

[crayon]

Hi!

I'm new here, and I'm trying to get a headstart in the development of system code and application code to support some projects of mine. I got a MIMXRT1020-EVK. This board has on board QSPI flash and some SDRAM. I was using the McuXpresso SDK builder and IDE. But I started to use only the GCC toolchain (and the GCC version of the SDK) and uploaded the Jlink firmware to the openSDA debugger (with some help from a Zephyr RTOS tutorial, to make the probe Jlink compatible).

I was expecting to things not to work on the first go, but the linker script and the CMake build (both from a example project) created a elf file that I was able to load, debug and execute with the JlinkGDBServer and arm-none-eabi-gdb. It seams the QSPI flash is working and holds the code that's executed. Is there some bootloader always present that NXP shipped with that board? How can the QSPI flash work if the code that I build only contains code I can identify to not be some bootloader? Is that what NXP calls a BootROM? How would I ensure this functionality is present for development if I were to spin my own boards with some kind of external flash?

Thanks in advance for you advice.

[jhpadjustable]

The RT1020, like most ARM MCUs, has a system ROM with a bootloader for many of the chip's external interfaces. See the datasheet's Section 5, "Boot mode configuration", and the reference manual, "System Boot", for the details.