What is the functionality of SDRAM in IMX RT 1020 EVK

[narenchandra401]

Hi , we have been checking for a suitable MCU for our application and we came down to IMX RT 1020 . 

We wanted to go with this chipset and since it does not have a inbuilt Flash we planned to boot it from QSPI ,

But here when we were going to the EVK we did not understand one thing

As per the Document 

Here it says we can select the BOOT CFG pins to boot from QSPI 

But the question  is will it be executed directly from QSPI or will it do a copy into the SDRAM and them execute , because we had no idea why this SDRAM is there in the EVK . 

If you can guide us with the procedure it will be helpfull for us to place a order of the EVK and start development . 

Let us if it is directly executed from QSPI , also why the BOOT MODE pins are used ? is it to have two boot options and to switch between them ? 

Will the Boot config pins handle the booting or it will it be the Code that decides to boot from which memory resource .

Will the code to dump the application binary into QSPI be provided by NXP , How does it work , if some one can provide a clarity it would be helpful since this is the first time we are trying out a MCU with External memory .

[narenchandra401]

Purpose of SDRAM ? should we consider it in our custom board . does it boot directly boot from QSPI or will a copy of application binary be copied into SDRAM and then executed?

[samsaprunoff · Accepted solution]

Good day Naren,

I will try and answer a few of your questions:

Purpose of SDRAM

The RT1020 internally has limited on-board memory (DTCM, ITCM, and OCRAM... max 256 kB) which may be very limited in all but simple applications.  To address this limitation the EVK has provided 32 MB of SDRAM to allow the EVK to be used to develope larger and more sophisticated applications.

should we consider it in our custom board?

This will be dependent upon your intended application.  As mentioned above, you will need to determine if the internal memory of the RT1020 is large enough for your application.  If not then you may wish to include SDRAM, etc in order to have additional memory.  To get an idea of how much RAM is needed for various applications review and download the SDK example programs.  Compiling the various example programs will reveal how much Flash and RAM is used.  From here you can determine if external RAM is required.

does it boot directly boot from QSPI or will a copy of application binary be copied into SDRAM and then executed?

This will be dependent upon your intended application and use of the RT1020 and/or the EVK.  The SDK Example programs are designed to run directly out of the Flash (QSPI) Memory... in other words XIP - eXecute-In-Place.  You can relink the sample application to run out of internal RAM, but to do so you will need the EVK's on-board debugger or an external debugger to load the application into RAM.  Currently, there are no direct RT102x examples which allow the EVK to boot from Flash and then copy the application into the SDRAM, and then execute from SDRAM.  However, I found this thread which provides some guidance on what is required on the RT1050:

RT1050 - Booting from serial NOR flash to SDRAM 

Interestingly, if you read the PDF included within the zip file NXP has stated that running your code out of flash generally provides better performance than out of SDRAM.

I hope the above helps answer a few of your questions.

Cheers,

Sam