LPC55S69 : AHBCLKCTRLx registers and PowerDown mode

[EugeneHiihtaja]

Hi !

I can see AHBCLKCTRLx registers are used for enable clock of peripheral devices.

But it is not written anywhere if all clock setting remains after wakeup from PowerDown mode.

I assume they should but may be PowerDown API disable those and reenable those again.

From other side every enabled peripheral consume some uA/per Mhz and it have sense to disable clock of nonused peripheral if it not used.

my MCU wakeup from Powerdown sometimes but not all peripherals are used every wakeup.

I think I should disable clocks of some peripherals and enable clocks again for only used peripherals while next alive interval after PowerDown wakeup.

Is this right technique ? Or how PowerDown API manipulate with peripheral clock setting registers ?

Can clock manipulation help to conserve some energy in Active mode ?

Regards,

Eugene.

[xiangjun_rong]

Hi, Eugene,

In order to save power, I think it is okay to disable clocks of some peripherals and enable clocks again for only used peripherals while next alive interval after PowerDown wakeup.

BR

XiangJun Rong

[EugeneHiihtaja]

Hi xiangjun.rong‌ !

Let's take exact example. RNG consume 17uA per Mhz and at 12Mhz it will be 204uA ( ~0.2mA).

What is quite huge value. But from DS is not so clear when it consume power, when just enabled or when random values is read from peripherals.

My FW is not so often to use RNG and may be I should disable it if it not effect for quality of random values.

Should I disable RNG in PMC->PDRUNCFGCLR0  register and disable clock

OR

disabling clock is enough for minimize consumption to minimal level ?

Regards,

Eugene

[EugeneHiihtaja]

Hi xiangjun.rong‌ !

I mean what is minimal configuration is need for disable unused peripherals.

In my case not all of them are used after PowerDown wakeup and can be reinitialized at the moment what they need.

I think if peripheral mentioned in PDRUNCFGCLR0 e.g Table 292. it should be disabled.

For example TRNG , ADC and clock is disabled after that.

But in case of Flexcomm interfaces, may be clock disabling is need only.

So what is right way to save energy in case of peripherals if they temporary not in use ?

Regards,

Eugene