CCS/MSP432P401R: MSP432P401R - Not being able to put design into low power mode

Wheezy D.

Part Number: MSP432P401R

Tool/software: Code Composer Studio

Hi,

So based off many examples I see that I need to use

__enable_irq();

__wfi();

in order to enter low power mode in the msp432. Now exit low power mode I have to use the following

SCB_SCR &= ~SCB_SCR_SLEEPONEXIT;

The problem is that code composer is giving the following error 

Multiple markers at this line
    - #20 identifier "SCB_SCR_SLEEPONEXIT" is 
     undefined
    - #20 identifier "SCB_SCR" is undefined

I do not understand why it is giving me this error. If you guys have any input please let me know. Thank you

I am using CCS 6.2.0 if that makes a difference.

Thank you

over 8 years ago

0 Bruce McKenney over 8 years ago

Guru 100405 points

This looks like a CMSIS thing. You probably want

SCB->SCR &= ~SCB_SCR_SLEEPONEXIT_Msk;

That said, the ARM UG (DUI0553A Table 4-12) says that SLEEPONEXIT is 0 at reset, so if you don't mess with it you probably don't need this line of code at all.

0 Wheezy D. over 8 years ago in reply to Bruce McKenney

Prodigy 70 points

That seemed to have fixed the error. I will test it into a bit. Thank you

if I don't need it then how would I come out of low power mode after I put it into low power mode?

0 Bruce McKenney over 8 years ago in reply to Wheezy D.

Guru 100405 points

You need the bit to be 0 to wake up main(), but I was suggesting that it is probably already 0 (the core doesn't switch it to 1 on its own).

Including that line of code doesn't hurt anything.

0 Evan W over 8 years ago

TI__Mastermind 40450 points

Wheezy,

As Bruce said, I believe the proper naming for the macro is SCB_SCR_SLEEPONEXIT_Msk;

Example is below:
dev.ti.com/.../

What example are you looking at? Have you updated your code example pack along with your updates to CCS?

Another thing to note is it's important to use a __DSB(); as noted in this doc before going to WFI.
infocenter.arm.com/.../DAI0321A_programming_guide_memory_barriers_for_m_profile.pdf

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CCS/MSP432P401R: MSP432P401R - Not being able to put design into low power mode