MagTag LEDs flash on waking from deep sleep

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Assessment

Difficulty
4/5
Estimated time
3-5 days
Newbie friendliness
25/100
Issue type
Bug
Clarity
Mostly clear
Activity status
Active
Tech stack
c, python
Domain
embedded-iot

Research direction

The reproduction is the alarm.exit_and_deep_sleep_until_alarms snippet on a MagTag (ESP32-S2), and the report says the flash first appears between 10.2.1 and 10.3.0, so start by bisecting that range. Look at the ESP32-S2 port's deep-sleep and wake path and at what initializes the NeoPixels on boot. Done means the NeoPixels no longer flash yellow after waking, confirmed on real MagTag hardware, since the pretend-sleep mode does not reproduce it.

Written by the indexing model from the issue text.

Description

bug
CircuitPython version and board name
Adafruit CircuitPython 11.0.0-alpha.3-9-g1ae2bac84e on 2026-11-13; Adafruit MagTag with ESP32S2
Code/REPL
import time
import alarm

print("Awake.")
time.sleep(5)
time_alarm = alarm.time.TimeAlarm(monotonic_time=time.monotonic() + 15)
print("Entering deep sleep.")
alarm.exit_and_deep_sleep_until_alarms(time_alarm)
Behavior

(See Item #1 in "Additional Information")

code.py output:
Awake.
Entering deep sleep.

Code done running.
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.

Adafruit CircuitPython 11.0.0-alpha.3-9-g1ae2bac84e on 2026-11-13; Adafruit MagTag with ESP32S2

Description
  1. Neopixels flash yellow 4x on waking from deep sleep (does not flash the initial blue)
Additional information
  1. Does not actually happen when running code above, per item 2 immediately following. To my knowledge I don't have a way to access the serial output while also putting the board into actual deep sleep (not pretend)
  2. Does not happen when Magtag is plugged in (i.e. pretending to deep sleep)
  3. Behavior is not present in 10.2.1 (no LEDs flash on wakeup from deep sleep), but is present on everything I've tested beyond that (10.3.0, 10.3.2, absolute newest 11.0.0 as listed above)

(Opened per recommendation of tannewt: https://forums.adafruit.com/viewtopic.php?t=225848)

Dominant language
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