alarm.exit_and_deep_sleep_until_alarms(pin_alarm) fails to deep sleep on Xiao ESP32 C6

[timshac]

CircuitPython version and board name

Adafruit CircuitPython 9.2.6 on 2025-03-23; Seeed Xiao ESP32-C6 4MB Flash 512KB SRAM with ESP32-C6FH4

Code/REPL

import board
import alarm
import microcontroller
import digitalio

# LED pin for observing if deep sleep was reached (LED will go out)
LED_PIN = microcontroller.pin.GPIO15
led = digitalio.DigitalInOut(LED_PIN)
led.direction = digitalio.Direction.OUTPUT
led.value = False  # turn on LED

pin_alarm = alarm.pin.PinAlarm(pin=board.D9, value=True, pull=False)
alarm.exit_and_deep_sleep_until_alarms(pin_alarm)
# board does not deep sleep here (above)
# this code (below) will correctly sleep, forever:
# alarm.exit_and_deep_sleep_until_alarms()

Behavior

With the pin_alarm, the board will not sleep:

alarm.exit_and_deep_sleep_until_alarms(pin_alarm)

The device will not deep sleep.

With no alarms, the board will sleep forever:

alarm.exit_and_deep_sleep_until_alarms()

This code will correctly deep sleep.

Deep sleeping correctly works with a time alarm:

time_alarm = alarm.time.TimeAlarm(monotonic_time=time.monotonic() + 10)
alarm.exit_and_deep_sleep_until_alarms(time_alarm)

This code will correctly deep sleep, and wake up 10s later.

Description

No response

Additional information

No response

[dhalbert]

If you jumper D9 (GPIO20) to ground, does it sleep? Is anything connected to D9?

[timshac]

Good point.

If I strap D9 to ground or 3V3, the board still does not sleep.

I tried with the following alarms individually, all which failed to sleep:

pin_alarm = alarm.pin.PinAlarm(pin=board.D9, value=True, pull=False)
pin_alarm = alarm.pin.PinAlarm(pin=board.D9, value=False, pull=True)
pin_alarm = alarm.pin.PinAlarm(pin=board.D9, value=False)
pin_alarm = alarm.pin.PinAlarm(pin=board.D9, value=True) 

Thanks for having a look.