topic Re: Core / Peripheral States after wakeup from low power mode in LPC Microcontrollers

Core / Peripheral States after wakeup from low power mode

simonwyss — Mon, 31 Jul 2017 07:11:26 GMT

Which peripherals are powered after different low power states?

I found some information in the application note AN11611 and the user-manual UM10850 but I don't know if the RTC is always started after reset from sleep, deep-sleep or power-down mode?
If I use only the IRC as clock, I think the IRC has to start after the sleep, deep-sleep or power-down mode. Because ther is no other clock available.

However, when I switch to the RTC (32kHz) bevor going to sleep, deep-sleep or power-down, what happens on wakeup?
Is the IRC automatically started? Is the main-clock-source automatically switched to the IRC clock?
If not, I would have to switch the main-clock-source manually to IRC (with the 32kHz Clock, using 32us for each CPU cycle)

Thank you in advance for your help!

There seems to be an error in the AN11611 on page 5: The IRC is shutdown in Deep-Sleep according to the user-manual:

Re: Core / Peripheral States after wakeup from low power mode

jeremyzhou — Tue, 01 Aug 2017 05:35:48 GMT

Hi Simon Wyss ,

1) when I switch to the RTC (32kHz) bevor going to sleep, deep-sleep or power-down, what happens on wakeup?

I think the MCU will resume execute after wake up events happen.
Have a great day,
TIC

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Re: Core / Peripheral States after wakeup from low power mode

simonwyss — Tue, 01 Aug 2017 07:31:01 GMT

Hi jeremyzhou
Thank you for your reply!

1) Which is the main-clock-source after wakeup?

- RTC (32kHz)

- IRC (12MHz)

2) Is the IRC always powered up after wakeup?

Re: Core / Peripheral States after wakeup from low power mode

jeremyzhou — Tue, 01 Aug 2017 08:54:49 GMT

Hi Simon Wyss,

1) Which is the main-clock-source after wakeup?

- RTC (32kHz)

- IRC (12MHz)

Depend on the previous option configured, the MCU will resume execute with the original clock source after wake up.

Please you can have a try.
Have a great day,
TIC