topic K82: LLWU muxed with peripheral lines in Kinetis Microcontrollers

K82: LLWU muxed with peripheral lines

EugeneHiihtaja — Wed, 09 Jan 2019 12:04:15 GMT

Hello !

I can see in RM written like this:

1. Using the LLWU module, the external pins available for this chip do not require the associated peripheral function to be enabled. It only requires the function controlling the pin (GPIO or peripheral) to be configured as a digital input to allow a transition to pass to the LLWU"

Can I undestand it like this : if pin role in peripheral is also input, it is no need to remux pin as gpio input to have LLWU wakeup capabilities ?

I'm using LPUART1 and configure RX pin on PTC3 pin what is also LLWU_P7 input.

/* PORTC3 (pin B8) is configured as LPUART1_RX */
PORT_SetPinMux(LPUART1_RX_PORT, LPUART1_RX_PIN, kPORT_MuxAlt3);

And If I add LLWU capability :

LLWU_SetExternalWakeupPinMode(LLWU, LLWU_WAKEUP_P7_IDX, kLLWU_ExternalPinFallingEdge);

LLWU wakeup works without any problem from LLS3 mode to RUN mode

If I remux RX pin as GPIO input - LLWU wakeup works as well.

So this is feature OR some side effect ?

Regards,

Eugene

Re: K82: LLWU muxed with peripheral lines

kerryzhou — Thu, 10 Jan 2019 03:35:45 GMT

Hi Eugene,

Yes, you are right.

You just need to configure the LLWU pin function is enough to wake up the MCU, don't require the associated peripheral function to be enabled.

So, please configure the LLWU pin function with this API LLWU_SetExternalWakeupPinMode.

Wish it helps you!

If you still have question about it, please kindly let me know.

Have a great day,
Kerry

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Re: K82: LLWU muxed with peripheral lines

EugeneHiihtaja — Thu, 10 Jan 2019 07:39:55 GMT

Hi Kerry !

But what means "don't require the associated peripheral function to be enabled" ?

If pin muxed as LPUART RX e.g kPORT_MuxAlt3, it can stay like this and LLWU wakeup will work.

Or it means it is not mandatory to enable LPUART functionality.

Regards,

Eugene

Re: K82: LLWU muxed with peripheral lines

kerryzhou — Thu, 10 Jan 2019 07:54:35 GMT

Hi Eugene,

From my understand it is the port mux function, not the detail peripheral functionality.

Have a great day,
Kerry