Deep Sleep Summary

[sslupsky]

@dmayorquin Did you resolve this issue? Looking at your code, one question comes to mind that I have been looking to find an answer to.

You use py.go_to_sleep() to enter sleep mode which is part of the Pysense class.

Is that that call functionally equivalent to machine.deepsleep() ?

[jcaron]

@sslupsky if you have one of the older modules (LoPy 1, SiPy, WiPy 2), then there is an issue with the “native” deep sleep (machine.deepsleep) which results in a higher than expected power draw during deep sleep (>10 mA instead of 10-20 uA).

For those modules, the workaround to achieve low current deep sleep is to use an external board: Deep Sleep Shield, PySense or PyTrack, and the relevant library. This will cut all power to the module during deep sleep.

If you use one of the more recent modules, you should in most cases use the native deep sleep.

[dmayorquin]

Hi @sslupsky, I solved the issue and the complete code is here: https://forum.pycom.io/topic/3594/how-to-deep-sleep-with-sipy-pysense-3-7v-lipo/3

As @jcaron says, machine.deepsleep() works well with the new hardware, but I'm not sure it works too when your setup has a shield like Pysense. In that case I've read that you should use the deep sleep method from Pysense library (or Pytrack or whatever shield you're using).

[sslupsky]

Hi @dmayorquin ,

Your post was extremely helpful, thank you for pointing that out. It is encouraging that you achieved < 20uA sleep current.

Thank you @jcaron for the clarifications. I should have mentioned that I am using a Pysense and LoPY4.

I think I understand now that when you use a Pysense, use the Pysense API to put the system to sleep (ie: py.go_to_sleep()). If you have just a LoPY4 and are not using the Pysense, then use the machine.deepsleep() to put it to sleep.

[sslupsky]

Hi @jcaron I have another question regarding the Pysense. Is it possible to "sleep" the SD Card? Typically that would require that power to the card is turned off since most SD card sleep current specs are 100's of uA.

@administrators May I make a suggestion regarding a future update to the Pysense? Instead of an SD card, could you embed an eMMC chip instead? Or have both? eMMC chips typically have lower sleep current ratings and wider temperature ratings than SD cards.

[jcaron]

@sslupsky even if you are using a Pysense, it probably makes sense to use the native machine.deepsleep if you are using a LoPy 4. This keeps the RTC running, for instance.

[sslupsky]

@jcaron Thank you for the suggestion. I did not realize the Pysense API killed the RTC. That is good to know since I want to keep track of time. I have a code module working with the Pysense API now. I will try the native machine API.

[jcaron]

@sslupsky When you use deep sleep controlled by a PySense, PyTrack or the Deep Sleep Shield, deep sleep just completely powers off the xxPy module (ESP32, LoRa/Sigfox and/or LTE modem). No RTC, no ULP, no pin wake-up (on the ESP32), nothing...

If you use modules that support the native machine.deepsleep without the higher power consumption, it's probably always better to use that. The PySense/PyTrack/Deep Sleep Shield deep sleep was just a workaround.

[sslupsky]

@jcaron Ahh, that explains it. Now I understand better. Thank you.

[philwilkinson]

@sslupsky I just wanted to add a little to this discussion for new boards e.g. LoPy4 on an expansion board (not Pysense/Pytrack).
-The machine.pin_deepsleep_wakeup() function works fine.
-Using machine.deepsleep(time_in_ms) works fine once only. When the time_in_ms is complete, the unit wakes up OK and runs main.py. machine.wake_reason() correctly identifies a RTC WAKEUP.

However, it is not possible to then run machine.deepsleep(time_in_ms) again. The unit thinks the time has already elapsed and immediately exits deepsleep.

[tuftec]

@philwilkinson I am not sure I agree with your findings.
I have been able to use the machine.deepsleep(60000) to put the device to sleep for 10 minutes, wake up and then reboot my code. My code continues to run as expected, waking up every 10 mins.
I am using a LoPy4.
I also use the wake identification capability to differentiate between a reset/power up and a wake from sleep.

Peter.

[sslupsky]

@philwilkinson Thanks for the heads up. I have a Pysense and so far the machine.deepsleep() appears to work. I've had it running continuously for about a day now: Wake, send LoRa data packet, Sleep.

I also posted a question regarding the amount of time it takes the LoPY4 to wake. In my simple Wake, send LoRa data packet, Sleep application, it takes about 4.5 seconds to wake (I have a 10 second sleep period and the total time Wake to Wake is about 14.5 seconds). Are you aware of any way to optimize that? Or perhaps reduce the power consumption during the wake / boot?

Thanks again for the feedback.

[jcaron]

@sslupsky if you are measuring wake to wake then you have the LoRa send time included, not just boot time.

If you use LoRaWAN, then don’t forget that there’s at least 2 seconds after send for the RX1 and RX2 windows, possibly a lot more if the network sends a higher RX1 delay.

Also, a LoRa packet can be pretty slow to send in the slower data rates. It can be even longer for LoRaWAN with the frame overhead, but even in raw LoRa you need to count the preamble. The smallest frame sent over LoRaWAN at SF12 takes nearly 1.5 seconds to send.

[philwilkinson]

@tuftec, yes you are correct, the machine.deepsleep() machine.remaining_sleep_time() and pin_deepsleep_wakeup() functions all work fine.

I have isolated my problem was with the LoRa publishing code. When I commented out the lora_publish in my code below everything worked fine. The bug must be something to do with nvram functions i am using in my lora_publish function. Perhaps this bug is best published in a new thread. Thanks for the comment.

Code published to allow others a quick start!

import machine
import utime
from machine import Pin
import pycom
import config #user defined
#import LoRa_publish #user defined

rst=machine.reset_cause()
if rst != 3: # if not woken from deepsleep
    utime.sleep(10) #to allow ctrl+C
    pycom.nvs_set('counter', 0)
    #button = Pin('P23', mode = Pin.IN, pull = Pin.PULL_UP)
    machine.pin_deepsleep_wakeup(pins = ['P23'], mode = machine.WAKEUP_ALL_LOW, enable_pull = True)
    machine.deepsleep(60000)
else:
    if (machine.wake_reason()[0])==1: #pin wakeup
        total_count = pycom.nvs_get('counter') +1
        pycom.nvs_set('counter', total_count)
        print('remaining deepsleep time is {}'.format(machine.remaining_sleep_time()))
        machine.pin_deepsleep_wakeup(pins = ['P23'], mode = machine.WAKEUP_ALL_LOW, enable_pull = True)
        machine.deepsleep(machine.remaining_sleep_time())

    elif (machine.wake_reason()[0])==2: #RTC timer complete
        print('timer completed')
        total_count = pycom.nvs_get('counter')
        print('counted {} button presses'.format(total_count))
        #LoRa_publish.publish(total_count) #INT published to TTN
        pycom.nvs_set('counter', 0)
        machine.pin_deepsleep_wakeup(pins = ['P23'], mode = machine.WAKEUP_ALL_LOW, enable_pull = True)
        machine.deepsleep(60000) #this does not restart a new interval!!