topic Re: Imprecise Bus Error when trying to make use of SDRAM on RT1020 EVK in i.MX RT Crossover MCUs

Imprecise Bus Error when trying to make use of SDRAM on RT1020 EVK

dykwong — Fri, 25 Nov 2022 09:35:43 GMT

I am using the NXP RT1020 EVK with MCUXpresso IDE v11.6.0 and the latest SDK version ksdk2_0.

The project is an example from the SDK: evkmimxrt1020_sai_edma_record_playback.

I am trying to make use of the onboard SDRAM (region RAM4) by declaring a global variable "test_array[4]". Building the project did not reveal any errors.

But when it is downloaded to be debugged, the "IMPRECISERR (2) Imprecise data bus error" popped up.

When this global variable is removed, the error does not appear.

I realise that this may be a duplication of another issue BOARD_InitBootClocks causes hard fault when put inside the SystemInitHook function . However, it is unclear how to achieve the SDRAM initialisation using the DCD mechanism.

Perhaps someone may shed some light on the method to perform SDRAM memory initialisation.

Re: Imprecise Bus Error when trying to make use of SDRAM on RT1020 EVK

jay_heng — Tue, 29 Nov 2022 02:26:55 GMT

You can check project setting to see whether XIP_BOOT_HEADER_DCD_ENABLE is set

Re: Imprecise Bus Error when trying to make use of SDRAM on RT1020 EVK

dykwong — Tue, 29 Nov 2022 03:09:46 GMT

Thanks, Jay.

I just tried it, and after downloading to the RT1020 EVK. The same error popped up.

In any case, I am very interested in getting more documentation on the the ways and means to configure project properties.

Also I have attached the project which generated the above behaviour.

Keep up the good work!

Re: Imprecise Bus Error when trying to make use of SDRAM on RT1020 EVK

dykwong — Tue, 29 Nov 2022 09:36:11 GMT

It should also be noted that the addition of "XIP_BOOT_HEADER_DCD_ENABLE=1" triggered the display of the following warning during build:

"SKIP_SYSCLK_INIT should be defined to keep system pll (selected to be SEMC source clock in SDK projects) unchanged"

Re: Imprecise Bus Error when trying to make use of SDRAM on RT1020 EVK

dykwong — Tue, 29 Nov 2022 10:10:20 GMT

Great news, Jay.

Defining the following in Project Properties > Settings > MCU C Compiler > Preprocessor resolved the issue:

SKIP_SYSCLK_INIT
USE_SDRAM
XIP_BOOT_HEADER_DCD_ENABLE=1