Thanks for the explanations guys.
I am feeling a bit stupid here looking at this function. I can read roughly what its doing, but where do all the values come from for these variables?
What is MODIFY_REG, SET_BIT, CLEAR_BIT ? Are these functions all of their own. They arent defined anywhere that i can see so cant tell whats inside them.
I still dont get this __WFI, __WFE thing at the moment. This is my first ever time trying to get a uC into sleep.
This line : SET_BIT(SCB->SCR, ((uint32_t)SCB_SCR_SLEEPDEEP_Msk)); sets the sleep bit although i cannot find out what value SCB_SCR_SLEEPDEEP_Msk is supposed to have?? Currently trying to find the section in the datasheet for these registers.
So am i right in that once you set this bit that the CPU goes to sleep as soon as it is set?
Then is this part waiting for the interrupt to wake the CPU back up??
if(STOPEntry == PWR_STOPENTRY_WFI)
{
/* Request Wait For Interrupt */
__WFI();
}
else
{
/* Request Wait For Event */
__SEV();
__WFE();
__WFE();
}
When the interrupt triggers do i then clear the bit inside the interrupt and the CPU starts back up? using this line?
CLEAR_BIT(SCB->SCR, ((uint32_t)SCB_SCR_SLEEPDEEP_Msk));
Below is the whole function:
void HAL_PWR_EnterSTOPMode(uint32_t Regulator, uint8_t STOPEntry)
{
/* Check the parameters */
assert_param(IS_PWR_REGULATOR(Regulator));
assert_param(IS_PWR_STOP_ENTRY(STOPEntry));
/* Select the regulator state in Stop mode: Set PDDS and LPDS bits according to PWR_Regulator value */
MODIFY_REG(PWR->CR, (PWR_CR_PDDS | PWR_CR_LPDS), Regulator);
/* Set SLEEPDEEP bit of Cortex System Control Register */
SET_BIT(SCB->SCR, ((uint32_t)SCB_SCR_SLEEPDEEP_Msk));
/* Select Stop mode entry --------------------------------------------------*/
if(STOPEntry == PWR_STOPENTRY_WFI)
{
/* Request Wait For Interrupt */
__WFI();
}
else
{
/* Request Wait For Event */
__SEV();
__WFE();
__WFE();
}
/* Reset SLEEPDEEP bit of Cortex System Control Register */
CLEAR_BIT(SCB->SCR, ((uint32_t)SCB_SCR_SLEEPDEEP_Msk));
}
