Please tell me the setting function of deep sleep

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Please tell me the setting function of deep sleep [Copy link]

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Please see if the following function can achieve its: When the parameter is FALSE: it will not automatically enter sleep mode after waking up, assuming that the first bit of SCR is 1 before entering the function

/**
******************************************************************************
** \brief Enter deep sleep mode
**
** \input bOnExit - TRUE: After exiting exception handling, it will automatically enter sleep again;
** FALSE: It will not automatically enter sleep after waking up
**
** \retval NULL
*****************************************************************************/
void Lpm_GotoDeepSleep(boolean_t bOnExit) // ? Error FALSE: It will not automatically enter sleep after waking up It seems that it will not work when it is FALSE
{
SCB->SCR |= SCB_SCR_SLEEPDEEP_Msk;
SCB->SCR |= 1u<<bOnExit;

// When bOnExit = TRUE, 1 < 1 = 2, that is, set the first bit of SCR to 1 to realize the function that when exiting the exception handling and returning to the program thread, the processor automatically enters the sleep mode (WFI) // When bOnExit = false, 1 < 0 = 1, that is, set the 0th bit of SCR to 1, which has no effect on the 1st and 2nd bits of SCR

// i.e. SCB->SCR |= 1u<<0 --> SCB->SCR |= 1u Set bit 0 to 1 and have no effect on bit 1

That is, when the first bit is 1, you cannot change the first bit 1 to 0.

It also fails to achieve the expected function of [no longer automatically entering sleep after waking up]

It is still in the state of [Automatically enter sleep again after exiting exception handling]

}

Please check if my analysis in red font is correct. Thank you. Another question is what is the initial value of SCR after power-on reset of the microcontroller? Thank you.

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You are so hardworking, don’t you sleep?

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Deeply confused published on 2021-6-26 09:05 You are so hardworking, don’t you sleep?

Due to the pressure of life, no one wants to get up early.

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What is the initial value of SCR after power-on reset of the microcontroller? Reset value: 0x0000 0000

I don't know what's going on with your problem, but I found a problem in your program:

You said: "That is, SCB->SCR |= 1u<<0 --> SCB->SCR |= 1u sets bit 0 to 1, which has no effect on bit 1." This is true, but it does have an effect on bit 0. The manual says that bit 0 must remain 0.

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Deep confusion published on 2021-6-26 10:00 What is the initial value of SCR after power-on reset of the microcontroller? Reset value: 0x0000 0000 Not for your question...

Thank you very much. The program is not written by me, but a piece of code from a program downloaded from the Internet.

Since it is reserved, why is it required to be 0?

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Shenzhen Xiaohua published on 2021-6-26 15:50 Thank you very much. The program was not written by me, but a piece of code from a program downloaded from the Internet. Since it is reserved, why is it required to be 0...

I don't know if setting it to 1 will have any effect, but setting it to 0 will definitely have no effect, so in this case just follow the manual for safety. Maybe the manufacturer knows what function setting this bit to 1 will have, but doesn't intend to open this function to you, so they stipulate that this bit must be 0.