Ok now we have a duplicate for this issue, which is good, it means that it will be solved one way or another.

So now we need to discuss the solutions.

Solution 1 (time based): PR 6482:

• provide full control over X1 and X18 wake up pins in the machine/pyb module in an "easy way"
  - full control:
  - set wake up pin
  - set trigger on falling/raising wake up
  - get the reset_cause
  Solution 2 (time based): PR 6494 (this one)
• handle full control over X1 and X18 to the user
  - full control:
  - set wake up pin in python
  - set trigger on falling/raising wake up in python
  - get the reset_cause in python

Both solution have advantages and drawbacks.

Drawbacks:
Solution 1:
a lot of C code as we will need to break the calling of machine_deepsleep from pyb_standby in order to control the pins and will have to duplicate the reset_cause and have a fall-through machine_reset_cause if pyb_reset_cause is not X1/X18

Solution 2:
the complexity is moved to the user/developer

How can we have this discussion ?

Duplicate: #6482

This PR is a bugfix. It ensures that the Pyboard D behaves similarly to Pyboard 1.x. There is no conflict with alternative micropower solutions.

@dpgeorge Any thoughts on this? It does seem unfortunate to lose functionality which has been available for years on Pyboard 1.x. Is there a reason for this?

@peterhinch Sorry for the possibly dumb question but I'm not super familiar with STM32 power management. Is there a hidden interaction that I don't understand -- why is this way of solving it necessary? i.e. why doesn't removing the // disable wake-up flags line achieve the same thing? Is there an AN or RM we can link to that explains this?

It would achieve the same thing. I gather Damien has identified a hardware issue whereby the wakeup sources must be disabled while clearing the global flag. This code comment indicates that this is the case. I therefore used this approach, which works in my testing.

There are forum users asking about this. Is there a reason for not implementing this simple fix?

Sorry, this PR got really lost.

I agree with the fix, it is needed. ST examples do it this way (disable wake-up sources, clear wake-up flag, re-enable wake-up sources, enter stand-by mode).

Tested and merged in 0facd89

Thank you very much @peterhinch !