reproducible problem with infinite loop of deep sleep

[garberw]

CircuitPython version and board name

Adafruit CircuitPython 9.2.8 on 2025-05-28; Raspberry Pi Pico W with rp2040

Code/REPL

#!/usr/bin/env python3                                                                                                                                                                                                                                                                                                                                                                        
import os
import time
import busio
import wifi
import microcontroller
from microcontroller import watchdog
from watchdog import WatchDogMode
import socketpool
import board
import alarm

# this gives you time to copy something else to code.py if CIRCUITPY won't mount                                                                                                                                                                                                                                                                                                              
def microcontroller_reset():
    ttt = 7
    print(f'resetting microcontroller in {ttt:f} seconds')
    for idx in range(ttt):
        print(f'feed_sleep  iter = {idx:d} / {ttt:f}   ......')
        time.sleep(1)
        print(">>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> feed watchdog timer")
        watchdog.feed()
    microcontroller.reset()

class FileClient:
    """stub"""
    def __init__(self):
        print('FileClient.__init__')
        self.i2c = busio.I2C(board.GP27, board.GP26)
        try:
            wifi_ssid     = os.getenv('CIRCUITPY_WIFI_SSID')
            wifi_password = os.getenv('CIRCUITPY_WIFI_PASSWORD')
            wifi.radio.connect(wifi_ssid, wifi_password)
            print('--------------------------  WIFI PASSED  --------------------------')
        except Exception as exc:
            print(f'wifi.radio.connection {exc=}')
            raise exc
        try:
            self.socket_pool = socketpool.SocketPool(wifi.radio)
            print('-----------------------  SOCKETPOOL PASSED  ----------------------')
        except Exception as exc:
            print(f'socketpool {exc=}')
            raise exc
        print('FileClient.__init__ PASS')

    def run(self):
        """stub"""
        print('run')
        for idx in range(4):
            print(f'---------------- awake and feeding {idx:3d} ----------------')
            watchdog.feed()
            time.sleep(5.0)
        print('---------------- reset 4 ----------------')
        microcontroller.reset()

def example_main():
    """stub"""
    try:
        print('example_main')
        loop_sleep_time = 12
        print(f'alarm.wake_alarm = {alarm.wake_alarm}')
        if not alarm.wake_alarm:
            print('wake up from reset;')
            print('start deep_sleep() before WatchDogTimerLocal.init();')
            ds_alarm = alarm.time.TimeAlarm(monotonic_time = time.monotonic() + loop_sleep_time)
            alarm.exit_and_deep_sleep_until_alarms(ds_alarm)
        print('wake up from alarm after deep sleep')
        weatherc = None
        print('!!!!!!!!!!!!!!!!!!!!!!! starting WatchDogTimerLocal !!!!!!!!!!!')
        watchdog.timeout = 8
        watchdog.mode = WatchDogMode.RESET
        print(">>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> feed watchdog timer")
        watchdog.feed()
        weatherc = FileClient()
        weatherc.run()
        print('---------------- reset 1 ----------------')
        microcontroller_reset()
    except Exception as exc:
        print(f"main exception {exc=}")
        if weatherc:
            weatherc.close()
        print('---------------- reset 2 ----------------')
        microcontroller_reset()

if __name__ == '__main__':
    example_main()

# eee eof

Behavior

Pretending to deep sleep until alarm, CTRL-C or file write.
Woken up by alarm.

Auto-reload is on. Simply save files over USB to run them or enter REPL to disable.
code.py output:
log.setLevel() level = 10
log.setLevel() level = 10
example_main
alarm.wake_alarm = <TimeAlarm>
wake up from alarm after deep sleep
!!!!!!!!!!!!!!!!!!!!!!! starting WatchDogTimerLocal !!!!!!!!!!!
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> feed watchdog timer
FileClient.__init__
--------------------------  WIFI PASSED  --------------------------
-----------------------  SOCKETPOOL PASSED  ----------------------
FileClient.__init__ PASS
run
---------------- awake and feeding   0 ----------------
---------------- awake and feeding   1 ----------------
---------------- awake and feeding   2 ----------------
---------------- awake and feeding   3 ----------------
---------------- reset 4 ----------------

[22:25:36.332] Disconnected
[22:25:37.333] Warning: Could not open /dev/ttypicoi (No such file or directory)
[22:25:37.333] Waiting for tty device..
[22:25:47.345] Connected to /dev/ttypicoi
Auto-reload is on. Simply save files over USB to run them or enter REPL to disable.

Press any key to enter the REPL. Use CTRL-D to reload.
Pretending to deep sleep until alarm, CTRL-C or file write.
Woken up by alarm.

Auto-reload is on. Simply save files over USB to run them or enter REPL to disable.
code.py output:
log.setLevel() level = 10
log.setLevel() level = 10
example_main
alarm.wake_alarm = <TimeAlarm>
wake up from alarm after deep sleep
!!!!!!!!!!!!!!!!!!!!!!! starting WatchDogTimerLocal !!!!!!!!!!!
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> feed watchdog timer
FileClient.__init__
--------------------------  WIFI PASSED  --------------------------
-----------------------  SOCKETPOOL PASSED  ----------------------
FileClient.__init__ PASS
run
---------------- awake and feeding   0 ----------------
---------------- awake and feeding   1 ----------------
---------------- awake and feeding   2 ----------------
---------------- awake and feeding   3 ----------------
---------------- reset 4 ----------------

[22:26:18.091] Disconnected
[22:26:19.092] Warning: Could not open /dev/ttypicoi (No such file or directory)
[22:26:19.093] Waiting for tty device..
[22:26:31.108] Connected to /dev/ttypicoi
Auto-reload is on. Simply save files over USB to run them or enter REPL to disable.

Press any key to enter the REPL. Use CTRL-D to reload.
Pretending to deep sleep until alarm, CTRL-C or file write.
Woken up by alarm.

Auto-reload is on. Simply save files over USB to run them or enter REPL to disable.
code.py output:
log.setLevel() level = 10
log.setLevel() level = 10
example_main
alarm.wake_alarm = <TimeAlarm>
wake up from alarm after deep sleep
!!!!!!!!!!!!!!!!!!!!!!! starting WatchDogTimerLocal !!!!!!!!!!!
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> feed watchdog timer
FileClient.__init__
--------------------------  WIFI PASSED  --------------------------
-----------------------  SOCKETPOOL PASSED  ----------------------
FileClient.__init__ PASS
run
---------------- awake and feeding   0 ----------------
---------------- awake and feeding   1 ----------------
---------------- awake and feeding   2 ----------------
---------------- awake and feeding   3 ----------------
---------------- reset 4 ----------------
[22:27:02.031] Disconnected
[22:27:03.032] Warning: Could not open /dev/ttypicoi (No such file or directory)
[22:27:03.032] Waiting for tty device..
[22:27:30.065] Connected to /dev/ttypicoi
Auto-reload is off.
Running in safe mode! Not running saved code.

You are in safe mode because:
CircuitPython core code crashed hard. Whoops!
Hard fault: memory access or instruction error.
Please file an issue with your program at github.com/adafruit/circuitpython/issues.
Press reset to exit safe mode.

Description

After a couple (or a great many) iterations, following a deep sleep the usb tty output of the pico boots to the circuit python (I think this is the) repl prompt >>> and does not resume running. This time above it actually booted into safe mode which is worse than usual. Also the first time you run this program it almost always boots to the >>> prompt and does not resume running; after resetting it with Control-C Control-D the second and following times it keeps running for a long time and eventually gets stuck booting to the repl >>> instead of resuming.

Desired behavior is to alternate; (1) sleep (2) run (1) sleep (2) run etc.

Additional information

note this is a synopsis of a larger program that has a lot of tty print statement debugging output.
I attach the tty with the udev rules

SUBSYSTEM=="tty",                       ATTRS{idVendor}=="239a",ATTRS{idProduct}=="8120",ATTRS{serial}=="E66141040383362E",OWNER="garberw",GROUP="garberw",MODE="0600",SYMLINK+="ttypicoi"

in /etc/udev/rules.d/whatever.rules
and there is also an entry for the CIRCUITPY mount in udev and fstab;
I use the linux program screen applied to the linux program tio (terminal) to access and log the tty;

maybe it is just not triggering the udev rule fast enough to reconnect the tty; the beginning output of the program before sleeping is chopped off

[garberw]

udev rules got mangled udev rules are

ACTION=="add",   SUBSYSTEMS=="usb",KERNEL=="ttyACM[0-9]*"                           ,ATTRS{idVendor}=="239a",ATTRS{idProduct}=="8120",ATTRS{serial}=="E66141040383362E",OWNER="garberw",GROUP="garberw",MODE="0600",SYMLINK+="ttypicoi"
SUBSYSTEM=="tty",                       ATTRS{idVendor}=="239a",ATTRS{idProduct}=="8120",ATTRS{serial}=="E66141040383362E",OWNER="garberw",GROUP="garberw",MODE="0600",SYMLINK+="ttypicoi"
SUBSYSTEM=="block", KERNEL=="sd[a-z]1", ATTRS{idVendor}=="239a",ATTRS{idProduct}=="8120",ATTRS{serial}=="E66141040383362E",OWNER="garberw",GROUP="garberw",MODE="0600",SYMLINK+="picoi"

and fstab is

/dev/picoi        /media/picoi  vfat   ro,auto,nofail,noatime,nodiratime,uid=1000,gid=1000,fmask=0022,dmask=0022,sync        0       0

I tried adding time.sleep(8) as the first line in the program to wait for the tty to connect (like you do at the beginning of an arduino program); that may have helped but it still crashed after 1 hour;

next I did sudo apt purge modemmanager and am testing now. NOTE am running in tio terminal which is in turn running under screen terminal for logging;

[dhalbert]

I have not had to add custom udev rules. Are you doing this to get a consistent tty name?

tio --log will do logging.

[garberw]

yes I am doing this to get a consistent tty name I chose. the host is a Pi4b running raspbian. you can't detach and reattach to tio otherwise that could allow me to eliminate screen. Not sure how to run tio in background and then view logs with tail -f

[garberw]

I have a whole elaborate set of scripts for transferring files to the pico and recovering from lockups and so on. Is there some way to upload them to you if you are interested? attach .gz file?

[garberw]

am testing in tio without using screen as intermediary. figured out how to use in background with nohup etc.

[eightycc]

Pretending to deep sleep until alarm, CTRL-C or file write.

@garberw This indicates that the issue is in "pretend" deep sleep, not in actual deep sleep. In "pretend" deep sleep you will not achieve any power savings. To enter real deep sleep, your board cannot be connected to USB. Have you tested with real deep sleep?

I'm adding this issue to my list of Pico sleep issues and will attempt to reproduce with the script you've provided.

[garberw]

From the documentation (confused me a little):

If CircuitPython is connected to a host computer via USB or BLE the first time a deep sleep is requested, the connection will be maintained and the system will not go into deep sleep. This allows the user to interrupt an existing program with ctrl-C, and to edit the files in CIRCUITPY, which would not be possible in true deep sleep.

If CircuitPython goes into a true deep sleep, and USB or BLE is reconnected, the next deep sleep will still be a true deep sleep. You must do a hard reset or power-cycle to exit a true deep sleep loop.

Am currently seeing how long it will stay up with tio only and no screen. If and when that crashes will do a run with no usb tty connected. Regards.

[bablokb]

Real deep sleep should have no problems because it resets.

[garberw]

in my previous post ... there is something about how it crashes when reconnecting about the time it says "pretending to sleep";
I tried inserting a time.sleep(8) as the first line in the program to wait for the tty to connect. I think this helps to wait for it to connect before printing anything on the tty. Maybe I did not wait long enough (8 sec). With this modification it stayed working
longer but still eventually crashed.

Any help? is there a way to wait for the tty to be ready for output e.g. select like you do on arduino in the first line of code
while (!Serial); Staying up for 8 extra seconds uses a lot of power; it's only supposed to stay up for 15 seconds total
every 5 minutes; that's the target.

[garberw]

[08:56:37.042] Warning: Could not open tty device (No such file or directory)
[08:56:37.042] Waiting for tty device..
[08:56:48.055] Connected

The Waiting for tty device delay occurs while the udev rule for the /dev/picoi
(/media/picoi like /media/CIRCUITPYTHON usb flash drive) udev rule is recognizing the flash drive;
this is about the same time as the udev rule for the tty regognizes the tty;
this might be faster without the custom udev rule;
I need the udev rules because there are 5 similar picos in the project and I need consistent device names;

[dhalbert]

If you just take away the udev rule (and use just one device) does the problem happen.

Instead of sleeping, would it help to busy-wait on supervisor.runtime.usb_connected or supervisor.runtime.serial_connected?