Timing issue with machine.deepsleep

[mu88]

Hey everyone,

I'm facing a strange issue: after calling machine.deepsleep(300000) (sleep for 5 min), the Pico awakes after approx. 3 min.

I also checked machine.wake_reason() which returns 3.

Is there any explanation why the Pico wakes up two minutes early?

Here's the complete code if necessary.

Thank you for your help!

[mu88]

Interesting update: I've doubled the sleep time, i. e. now calling machine.deepsleep(600000) - but the Pico still wakes up after 3 min 😮

[robert-hh]

Looking at the code, the sleep time should range up to 2**32/1000, which is ~4200 seconds. Is WiFi enabled in your tests?
edit: The way it's implemented, deepsleep() is lightsleep() followed by a reset.

[robert-hh]

If power consumption matters, you could deinit WiFi and drop the machine.freq() to 18MHz before calling time.sleep(). That drops the current consumption to ~5 mA.

[mu88]

Thx for that hint - I'm already deinit-int the WiFi. Does dropping the machine frequency have an impact on the timing? And do you know whether there are already existing issues tracking the broken sleep APIs?

[robert-hh]

A short test showed, that time.sleep() still works right at 18 MHz. About earlier issues: A short search revealed a discussion I had at issue #9006. Issue #8994 may may also be interesting.

[mu88]

#9006 looks indeed very similar to my problem - so I have to find a way to trim MicroPython (i. e. remove modules I don't need) as soon as the next version of MicroPython gets released to get rid of the OutOfMemory problem

[mu88]

So I can confirm that calling machine.freq(18000000) reduces the power consumption from 24 mA to 15 mA