Django Busy GPIOs Raspberry Pi 5

Question

When trying to interface with the GPIO of the RPi 5 using gpiozero, I am running into an error stating that the GPIO is busy. The context is that I am running this code in a Celery task in Django.

The issue is similar to this, but the fix provided did not work in this context.

Full error trace

Exception in thread django-main-thread:
Traceback (most recent call last):
  File "/usr/lib/python3/dist-packages/gpiozero/pins/pi.py", line 408, in pin
    pin = self.pins[info]
          ~~~~~~~~~^^^^^^
KeyError: PinInfo(number=36, name='GPIO16', names=frozenset({'GPIO16', 16, 'BOARD36', 'WPI27', 'BCM16', 'J8:36', '16'}), pull='', row=18, col=2, interfaces=frozenset({'', 'uart', 'spi', 'dpi', 'gpio'}))

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/usr/lib/python3.11/threading.py", line 1038, in _bootstrap_inner
    self.run()
  File "/usr/lib/python3.11/threading.py", line 975, in run
    self._target(*self._args, **self._kwargs)
  File "/usr/lib/python3/dist-packages/django/utils/autoreload.py", line 64, in wrapper
    fn(*args, **kwargs)
  File "/usr/lib/python3/dist-packages/django/core/management/commands/runserver.py", line 110, in inner_run
    autoreload.raise_last_exception()
  File "/usr/lib/python3/dist-packages/django/utils/autoreload.py", line 87, in raise_last_exception
    raise _exception[1]
  File "/usr/lib/python3/dist-packages/django/core/management/__init__.py", line 375, in execute
    autoreload.check_errors(django.setup)()
  File "/usr/lib/python3/dist-packages/django/utils/autoreload.py", line 64, in wrapper
    fn(*args, **kwargs)
  File "/usr/lib/python3/dist-packages/django/__init__.py", line 24, in setup
    apps.populate(settings.INSTALLED_APPS)
  File "/usr/lib/python3/dist-packages/django/apps/registry.py", line 91, in populate
    app_config = AppConfig.create(entry)
                 ^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3/dist-packages/django/apps/config.py", line 224, in create
    import_module(entry)
  File "/usr/lib/python3.11/importlib/__init__.py", line 126, in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "<frozen importlib._bootstrap>", line 1206, in _gcd_import
  File "<frozen importlib._bootstrap>", line 1178, in _find_and_load
  File "<frozen importlib._bootstrap>", line 1149, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 690, in _load_unlocked
  File "<frozen importlib._bootstrap_external>", line 940, in exec_module
  File "<frozen importlib._bootstrap>", line 241, in _call_with_frames_removed
  File "/home/user/Desktop/PressureSwitchTestGUI/SD_18_GUI/app/__init__.py", line 3, in <module>
    from .celery import app as celery_app
  File "/home/user/Desktop/PressureSwitchTestGUI/SD_18_GUI/app/celery.py", line 9, in <module>
    from app.tasks import IO
  File "/home/user/Desktop/PressureSwitchTestGUI/SD_18_GUI/app/tasks.py", line 36, in <module>
    servo = PWMLED(servoControlPin)
            ^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3/dist-packages/gpiozero/devices.py", line 103, in __call__
    self = super().__call__(*args, **kwargs)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3/dist-packages/gpiozero/output_devices.py", line 392, in __init__
    super().__init__(pin, active_high=active_high, initial_value=None,
  File "/usr/lib/python3/dist-packages/gpiozero/output_devices.py", line 74, in __init__
    super().__init__(pin, pin_factory=pin_factory)
  File "/usr/lib/python3/dist-packages/gpiozero/mixins.py", line 75, in __init__
    super().__init__(*args, **kwargs)
  File "/usr/lib/python3/dist-packages/gpiozero/devices.py", line 549, in __init__
    pin = self.pin_factory.pin(pin)
          ^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3/dist-packages/gpiozero/pins/pi.py", line 410, in pin
    pin = self.pin_class(self, info)
          ^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3/dist-packages/gpiozero/pins/lgpio.py", line 126, in __init__
    lgpio.gpio_claim_input(
  File "/usr/lib/python3/dist-packages/lgpio.py", line 755, in gpio_claim_input
    return _u2i(_lgpio._gpio_claim_input(handle&0xffff, lFlags, gpio))
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3/dist-packages/lgpio.py", line 458, in _u2i
    raise error(error_text(v))
lgpio.error: 'GPIO busy'

Here is the Django settings.py file

"""
Django settings for project project.

Generated by 'django-admin startproject' using Django 5.0.

For more information on this file, see
https://docs.djangoproject.com/en/5.0/topics/settings/

For the full list of settings and their values, see
https://docs.djangoproject.com/en/5.0/ref/settings/
"""

from pathlib import Path

# Build paths inside the project like this: BASE_DIR / 'subdir'.
BASE_DIR = Path(__file__).resolve().parent.parent


# Quick-start development settings - unsuitable for production
# See https://docs.djangoproject.com/en/5.0/howto/deployment/checklist/



# SECURITY WARNING: don't run with debug turned on in production!
DEBUG = False

ALLOWED_HOSTS = ['localhost']


# Application definition

INSTALLED_APPS = [
    'app',
    'daphne',
    'channels',
    'django.contrib.admin',
    'django.contrib.auth',
    'django.contrib.contenttypes',
    'django.contrib.sessions',
    'django.contrib.messages',
    'django.contrib.staticfiles',
]

MIDDLEWARE = [
    'django.middleware.security.SecurityMiddleware',
    'django.contrib.sessions.middleware.SessionMiddleware',
    'django.middleware.common.CommonMiddleware',
    'django.middleware.csrf.CsrfViewMiddleware',
    'django.contrib.auth.middleware.AuthenticationMiddleware',
    'django.contrib.messages.middleware.MessageMiddleware',
    'django.middleware.clickjacking.XFrameOptionsMiddleware',
]

ROOT_URLCONF = 'project.urls'

TEMPLATES = [
    {
        'BACKEND': 'django.template.backends.django.DjangoTemplates',
        'DIRS': [],
        'APP_DIRS': True,
        'OPTIONS': {
            'context_processors': [
                'django.template.context_processors.debug',
                'django.template.context_processors.request',
                'django.contrib.auth.context_processors.auth',
                'django.contrib.messages.context_processors.messages',
            ],
        },
    },
]

WSGI_APPLICATION = 'project.wsgi.application'


# Database
# https://docs.djangoproject.com/en/5.0/ref/settings/#databases

DATABASES = {
    'default': {
        'ENGINE': 'django.db.backends.sqlite3',
        'NAME': BASE_DIR / 'db.sqlite3',
    }
}


# Password validation
# https://docs.djangoproject.com/en/5.0/ref/settings/#auth-password-validators

AUTH_PASSWORD_VALIDATORS = [
    {
        'NAME': 'django.contrib.auth.password_validation.UserAttributeSimilarityValidator',
    },
    {
        'NAME': 'django.contrib.auth.password_validation.MinimumLengthValidator',
    },
    {
        'NAME': 'django.contrib.auth.password_validation.CommonPasswordValidator',
    },
    {
        'NAME': 'django.contrib.auth.password_validation.NumericPasswordValidator',
    },
]


# Internationalization
# https://docs.djangoproject.com/en/5.0/topics/i18n/

LANGUAGE_CODE = 'en-us'

TIME_ZONE = 'UTC'

USE_I18N = True

USE_TZ = True


# Static files (CSS, JavaScript, Images)
# https://docs.djangoproject.com/en/5.0/howto/static-files/

STATIC_URL = 'static/'

# Default primary key field type
# https://docs.djangoproject.com/en/5.0/ref/settings/#default-auto-field

DEFAULT_AUTO_FIELD = 'django.db.models.BigAutoField'

CACHES = {
    "default": {
        "BACKEND": "django_redis.cache.RedisCache",
        "LOCATION": "redis://127.0.0.1:6379/1",
        "OPTIONS": {
            "CLIENT_CLASS": "django_redis.client.DefaultClient"
        },
        "KEY_PREFIX": "example"
    }
}

# django_celery/settings.py

# ...

# Celery settings
CELERY_BROKER_URL = "redis://localhost:6379"
CELERY_RESULT_BACKEND = "redis://localhost:6379"

# Daphne
ASGI_APPLICATION = "project.asgi.application"

Tasks.py code

# CELERY TASK PREREQUSITES
from celery import shared_task
from channels.layers import get_channel_layer
from asgiref.sync import async_to_sync

# GENERAL PREREQUSITES
import datetime
import time
from collections import deque

# ADC PREREQUSITES
import board
import busio
import adafruit_ads1x15.ads1115 as ADC
from adafruit_ads1x15.analog_in import AnalogIn as AnalogRead

# GPIO REREQUSITES
from gpiozero import PWMLED, Button
#from gpiozero.pins.lgpio import LGPIOFactory

# CONSTANTS
voltagePressureRelation = 300/5

# BUTTONS AND PWM
#fact = LGPIOFactory()


interruptPin = 21
servoControlPin = 16
pressureSwitchReadPin = 12

#servo = PWMLED(servoControlPin, pin_factory=fact)
#interruptButton = Button(interruptPin, pull_up=True, pin_factory=fact)
#switchState = Button(pressureSwitchReadPin, pull_up=True, pin_factory=fact)

servo = PWMLED(servoControlPin)
interruptButton = Button(interruptPin, pull_up=True)
switchState = Button(pressureSwitchReadPin, pull_up=True)