Reboot after Standby/LPU Standby exit in MPC574x

[svsagar92]

Hi,

I am using MPC5746C controller.

Regarding transition from Standby/LPU Standby  to DRUN.

After transition from  Standby/LPU Standby to DRUN, is it compulsory to re boot the Z4 core?

Can we start the code execution in Z4 where it stopped before Standby /LPU Standby transition occurred?

After Standby exit,

Is it possible to run the code similar to  STOP/LPU STOP exit,where core starts the execution from stopped address location  before STOP/LPU STOP Transition .

Regards

Vidyasagar

[martin_kovar]

Hello,

as soon as the microcontroller is switched into LPU run mode, e200z4 core is in similar state as it is in Standby mode. This means, it is not possible to continue from the point where e200z4 enters Standby or any of LPU-RUN/STOP/STANDBY and it is necessary to reboot e200z4 core.

Here is a notice from reference manual:

The exit sequence of this mode is similar to the reset sequence, and the resets to all but
power domain #0 are asserted with timing that is the same as reset PHASE1 through
PHASE3. However, in addition to booting from the default location, the chip can also be
configured to boot from the backup RAM. In the case of booting from backup RAM , it is
also possible to keep the flashes disabled by writing “01” to the FLAON fields in the
ME_DRUN_MC register prior to STANDBY0 entry.

If you have any other question, please feel free to write me back.

Regards,

Martin

[svsagar92]

Hi b55689,

I dont want to loss data and current context after standby exit.

After Exiting from Standby mode , I want to run the code from previous context (before standby mode request).

1.Is there any possibility to run from previous context after standby exit?

From Nxp documentation i read that ,

By going to  RAM boot up and RAM Retention from Standby exit ,we can run from the previous context where code stopped.

2.After Standby exit I am trying to boot up from RAM by changing MC_ME CADDR1 register, but unable to bootup

Please explain the details about query.

Regards

Vidyasagar

[petervlna]

Hi,

1.Is there any possibility to run from previous context after standby exit?

No. Standby exit is going trough reset.  You need to initialize micro first.

If you are talking about Standby RAM, it is ram which is active in standby mode, intended to be used for execution code on Z2 when LPU_Standby moved to LPU_RUN.

Exit from stand by is always trough reset as reference manual describes:

Regards,
Peter