Waking up KL05 using LLWU isr - ISR generated due to RTC alarm

[pradyumnakammar]

Hello all,

i'm writing a low power mode application where, processor is put to VLLS0 mode from RUN mode. i want to wake the processor using LLWU by  setting RTC alarm module.

i'm able to reset the processor or wake up through LLWU pin interrupt but failing to wake it up with RTC alarm.

Pls help me out

[pradyumnakammar]

Hi, Tian

i have done all those register setting business.. I feel RTC isnt running when i'm switch to VLL0S2 mode.

before going to the lowpower mode i.e when i'm in RUN mode (i have tried FEE and BLPI fast irc) RTC alarm works but not after switching to low-power mode VLLS0.

i dont know which part i'm missing!! processor wakes up from VLLS0 mode with raising edge falling edge GPIO in interrupt but not with RTC alarm

i think its something with MCG ... please help

[Paul_Tian · Accepted solution]

Hi, Kammardi

I think your issue is caused by incorrect clock setting. In VLLS0, you only can use RTC_CLKIN, such a external clock source for RTC, In reference manual, you can find "RTC_CR[OSCE] can override the configuration of the System OSC, configuring the OSC for 32kHz crystal operation in all power modes (except VLLS0) ".

Hope my reply can help you.

Best Regards

Paul

[pradyumnakammar]

Hi Tian,

now facing a new problem.

This is what i'm doin : at start up setting clock from FEI to FBI then FBI to BLPI core clock set to 2Mhz UART baud set to 4800.

problem :

1. some of the bits gets manipulated when recieved serially (4%error)

2. after setting clock to BLPI and if i enter VLPR mode the UART problem gets solved but LLWU wakeup(from VLLS1) does not work

[pradyumnakammar]

Hi, Tian

thank you for you replies, processor now wakes up with rtc alarm from VLLS1 to Run mode...

thank you so much

[pradyumnakammar]

HI, Tian

internal clock setting ? i feared so...

Does System OSC mean  the Fast and Slow IRC?

what can i probably do now to keep the processor up for sometime and then almost shut it for a specific time ?

could you give me some ideas to how i could get this achieved?

[Paul_Tian]

Hi, Kammardi

First, you need to check LLWU_ME value. Bit WUME5 in register LLWU_ME should be set.

Second, you can set a breakpointer to check if RTC alarm interrupt happen.

Hope my reply can help you.

Best Regards

Paul