VLLS3 wake up,but no reset flow, MK20DX128

diegocolombo — Mon, 05 Nov 2012 14:34:06 GMT

Hello.Please can i have help, hints or ideas?I'm trying to wake up from vlls3 mode using a switch on a pin, but something goes wrong.

I reduced code at example level to better focus on the problem:after reset 1)initialization2)an easy recognizable 4 seconds square wave is outputted on a pin,3) an infinite loop is entered,where another sequence of different frequency is repeatedly outputted,and the status of a button is polled;

if pressed ,the vlls3 mode is called,just after the button itself is configured as wakeup trigger source,then the uC goes to sleep in vlls3 mode.

Resumed code looks like this:

void main(void){

wdog_disable();

PE_low_level_init();

TogglePin2KHz_4Sec();//to see it on oscilloscope when it passes through this point,once-only

for(;;)//infinite loop {

TogglePin500Hz_1Sec();//to see it on oscilloscope when it passes through this point,repeatedly

if(BUTTON PRESSED) {

..... //prepare Button as wake up trigger event

asm("WFI")

}//end of if

}//end of for(;;)

}//end of main

I measure the power consumption by 1 ohm resistor and a digital multimeter with less significative digit representing 0.1uV->100nA(probably not actually),i tried to follow tips from AN4503 11.1.2 Tips for making low-power measurements on the bench.

I can see current absorption =20 mA in RUN mode,and few uA when i call vlls3,,so i can think to be entered in vlls3.Ok until there.

Pushing the button the absorption rises up to 20 mA,typical of RUN mode,but i can't see any square wave on the scope.Where is my program running?

Debugging with Cyclone Max adds hundreds of uA,but that is non the main problem, i can see the debug stopping during vlls3.When,i turn back in RUN mode the debugger appears able to follow the code,but no signal on output pin when code should toggle it.If i check registers inherent to that PORT_PIN they look unchanged,if compared to the previous RUN mode.Is the debug realistic?

Reading the AN4503 at page 31:

• VLLSx exits to Run mode through the reset flow.

• For Kinetis devices, after exit from VLLSx, execution starts with the instruction pointed to by the RESET vector address.

I should expect that the the code starts from RESET,initializing stack pointer,global variables etc.It is my expectation wrong?

In code examples i found that at least GPIO iniatilization is done in wake up ISR,so i done(see attached file).

Thanks for your attention,

Diego.

Original Attachment has been moved to: Test_VLLS3.c.zip

Re: VLLS3 wake up,but no reset flow, MK20DX128

diegocolombo — Thu, 20 Dec 2012 19:30:35 GMT

My fault,sorry

the project was started by another guy that in waiting for a K20 128K uC buided some code for a K20 256K ,

My lack of skill with debug tool aavoided me to notice that some registers were different(MC instead of SMC and so on)

Starting from zero the K20 works correctly,and restarts passing from reset.

checking the System Reset Status Register i can have one more confirmation that the VLLS mode was used .

Thanks again

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VLLS3 wake up,but no reset flow, MK20DX128

Re: VLLS3 wake up,but no reset flow, MK20DX128