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.

[eightycc]

Can reproduce issue on Adafruit Feather ESP32C6. Investigating.

[eightycc]

For the ESP32-C6, only pins GPIO0 through GPIO7 may be used for alarms. In low-power states, these are the only pins whose pads are powered. CircuitPython should be throwing a value error on the attempt to use GPIO20 as an alarm. From section 12.4 of "ESP32-C6 Technical Resource Manual":

Eight LP GPIO pins (GPIO0 ∼ GPIO7): These pins are always powered up and are not affected by any low-power modes, which makes them suitable for working as wake-up sources when the chip is in low-power modes. These pins can also work as regular GPIOs.

[eightycc]

The provided example is attempting deep sleep on GPIO20, a pin that is not supported for that purpose on the ESP32-C6. Attempting to use an unsupported pin on an Adafruit Feather ESP32C6 correctly results in a Value Error like this code.py:

import board
import alarm
import microcontroller
import digitalio
import time

LED_PIN = microcontroller.pin.GPIO15
led = digitalio.DigitalInOut(LED_PIN)
led.direction = digitalio.Direction.OUTPUT
led.value = True

time.sleep(10)
pin_alarm = alarm.pin.PinAlarm(pin=board.IO14, value=False, pull=False)
print("entering deep sleep...")
alarm.exit_and_deep_sleep_until_alarms(pin_alarm)

code.py output:
entering deep sleep...
Traceback (most recent call last):
  File "code.py", line 15, in <module>
ValueError: Can only alarm on RTC IO from deep sleep.

Code done running.

Changing the pin from IO14 to IO1:

pin_alarm = alarm.pin.PinAlarm(pin=board.IO1, value=False, pull=False)

while wiring a push button with a 10K pull-up to 3.3V and ground when pressed results in deep sleep until the button is pressed.

@timshac Please re-test using a supported pin and the latest 10.0.0 alpha.

Something that threw me off while testing: Entering deep sleep is not supported from REPL. This includes attempting to run a Python script by import test_deep or typing alarm.exit_and_deep_sleep_until_alarms.... This should be documented or corrected. See #10353.

[timshac]

import board
import time
import alarm
import digitalio
import microcontroller

LED_PIN = microcontroller.pin.GPIO15
led = digitalio.DigitalInOut(LED_PIN)
led.direction = digitalio.Direction.OUTPUT

for i in range(5):
    led.value = False  # turn on LED
    time.sleep(1)
    led.value = True  # turn off LED
    time.sleep(1)

pin_alarmD2 = alarm.pin.PinAlarm(pin=board.D2, value=False, pull=True) 
alarm.exit_and_deep_sleep_until_alarms(pin_alarmD2)

Board sleeps when not connected to repl.

I can confirm that the board correctly sleeps using an LP_* pin. Thank you!