MPC5604P PLL De-Initialization

[cthhk]

Dear Team:

We are using MPC5604P and we need to perform De-Initialization before entering low power mode, in other words, to restore everything of PLL to reset state.

Could you provide an example on how to do this?

Appreciate your help!

Best Regards,

Wang.

[petervlna]

Hi,

Here are the steps you need to perform.

1. make sure no periphery is running from PLL clock.

2. Configure target mode for IRC clock as system clock and PPL to be off in target mode in entry module.

3. Perform the mode transition to desired target mode

PLLs are now off and you can perform mode transition to low power modes.

Peter

[cthhk]

Dear Petr:

Thank you for your reply.

I also want to restore the contents of all the PLL registers to reset state, so that I can use the same PLL Initializing routine after the micro comes back to run mode.

Could you help to suggest the process of this? I tried but it seemed that sometimes it was not successful especially when both PLL0 and PLL1 are being used.

Best Regards,

Wang.

[petervlna]

Hi,

From programmers view this doesn't make any sense to me.

Why would you put PPL into reset state and then overwrite it with PLL configuration?

Just call PLL initialization and write the desired values into it. There is no need to put registers in reset state and then overwrite them.

Peter

[howell]

cthhk‌petervlna

Hi,

There are both Bootloader Program and Application Program in the same MCU.  

After a reset occurs, PLLs are firstly initialized by Bootloader, then they are overwritten by Application Program. 

If the relevant registers don't recover to reset state, maybe some errors will occur during the second PLLs' initialization.

In general, before jumping to Application Program from Bootloader Program, we expect the status of all  PLLs' registers goes back to reset state.

Expecting your reply!

Howell, From Beijing, China.

[petervlna]

Hi,

Only way to put register to reset state is to perform reset or manually write the reset value to register.

I expect that if you are going to use some peripheral, you will first do initialization of all relevant registers and then enable this peripheral. So it still makes no sense to rewrite the register twice.

Peter