stm32L011F4 internal RTC alarm, there is a state where it cannot be woken up

麻袋

stm32L011F4 internal RTC alarm, there is a state where it cannot be woken up [Copy link]

As the title says, using the internal RTC, the second interrupt can wake up in most cases, but there is a situation where it cannot wake up after low power consumption. I don’t know why, please help. This phenomenon has not yet been found to be 100% reproducible, it only occurs occasionally, and it has occurred on each of the 4 boards I have made.

Low power consumption process:

Enable RTC ALARM interrupt

Turn off ADC, DMA

Close serial port, timer

Close the IO port and set it to analog

Enable low power clock and clear wake-up flag

Set to stop mode,

_WIF()

Jacktang

Any flags that may be generated in the program must be cleared. If not, wake-up failure may occur.

Or after entering stop mode, have you tried to wake up through external interrupt?

chunyang

First determine whether there is an RTC clock oscillation stop problem, which can only occur when the power supply voltage is too low. If this problem is eliminated, it means that it is a software problem, so focus on checking the relevant programs.

麻袋

chunyang posted on 2021-8-23 20:51 First determine whether there is an RTC clock stop oscillation problem, which can only occur when the power supply voltage is too low. If this problem is eliminated, it means that it is a software problem, and focus on checking the relevant...

It may not be a problem of oscillation. I adjusted the position of RTC enable and changed it to enable before entering low power consumption (it was enabled during initialization before). This phenomenon did not occur yesterday and today. I guess it is because after enabling the alarm clock, the second interrupt happened to come, and at this time, the peripheral clock was set and the flag was cleared, resulting in sleep without clearing the flag, and no second interrupt was generated. I don't know if this makes sense.

chunyang

Madai posted on 2021-8-24 15:44 It may not be a start-up problem. I adjusted the position of RTC enable and changed it to enable before entering low power consumption (it was enabled during initialization before...

This you can only try yourself.

w494143467

This kind of problem is not 100% reproducible and is indeed difficult to find, but the focus is on RTC.

麻袋

w494143467 posted on 2021-8-25 11:51 This kind of problem is not 100% reproducible and is indeed difficult to find, but the focus is on RTC.

Well, by modifying the RTC enabling code position, this problem was solved. I can only guess that the previous problem was that after the alarm was enabled, the second interrupt came immediately, and when it happened to be in the process of entering low power consumption to set the clock and clear the flag bit, the interrupt flag bit was not cleared, resulting in the alarm wake-up interrupt no longer being generated. I am not sure whether this is the case.