IMX7ULP EVK LP Boot Mode M4 halts

[sina_farzinfard]

I'm trying to test IMX7ULP-EVK board (REV B1) using the image files in L4.9.88_2.0.0. The demo image which is power_mode_switch starts working in LP-Boot mode and spits out some messages that working task is running. But it halts before it can proceed to the power mode switch commands. 

I'm wondering, is there any specific image file just for testing M4 in LP-Boot and also is there any instruction on how to boot the A7 by M4 in LP-Boot mode? 

[igorpadykov]

Hi Sina

>how to boot the A7 by M4 in LP-Boot mode

I am afraid it is not supported as described in i.MX 7ULP Applications Processor Reference Manual

For "power_mode_switch" example one can folow attached readme and documentation

in SDK_2.7.0_EVK-MCIMX7ULP :Welcome | MCUXpresso SDK Builder 

Also use latest BSPs as L4.9.88_2.0.0 is old release and not more supported

Best regards
igor
-----------------------------------------------------------------------------------------------------------------------
Note: If this post answers your question, please click the Correct Answer button. Thank you!
-----------------------------------------------------------------------------------------------------------------------

[sina_farzinfard]

Thanks Igor,

I understand that M4's ROM does not boot A7 and that's how it's different from Dual mode. What I was looking for is on-demand booting of A7 when M4 is running in LP mode.

from table 35-6 Configuration parameters or eFUSEs used by ROM:

 

Also, is there any specific setting for making the image file for M4 when we want to run it in LP mode?

As I said, the image I used and copied in the QSPI flash works perfectly in dual mode. However, when I switch to the LP mode after successfully booting from ROM it gets stuck and does not function properly.

[Daniel_S]

Hi Sina,

did you solve that problem in the end?
We are trying to do the same thing and getting the exact same behaviour: the software provided with the EVK (*) does work correctly on the M4 when booted in dual boot but does nothing when booted in low power mode.

(*) demo app power_mode_switch, same when we recompile it from the SDK

[igorpadykov]

Hi Sina

> is there any specific setting for making the image file for M4 when we want to run it in LP mode?

no specific settings as described in sect.35.2.2.2.3.3 Low power boot :

In Low Power Boot boot mode, only the M4 core will boot up and run on the FIRC clock
frequency to conserve battery energy. The boot sequence of the M4 in Lower Power Boot
is similar to its normal boot sequence, except the processor, bus, and peripherals operate
on the FIRC clock or a divided version of the FIRC clock.

>when I switch to the LP mode after successfully booting from ROM it gets stuck and does not function properly.

seems it is necessary to add to m4 image codes for starting a7.

Best regards
igor