Merge pull request adafruit#1268 from brentru/aqi-node-guide

Code: Adafruit IO Air Quality Sensor

Author: ladyada

Adafruit_IO_Air_Quality/code.py

@@ -0,0 +1,190 @@
+import time
+import board
+import busio
+from digitalio import DigitalInOut
+import neopixel
+from adafruit_esp32spi import adafruit_esp32spi, adafruit_esp32spi_wifimanager
+from adafruit_io.adafruit_io import IO_HTTP
+from simpleio import map_range
+
+import adafruit_pm25
+import adafruit_bme280
+
+### Configure Sensor ###
+# Return BME280 environmental sensor readings in degrees Celsius
+USE_CELSIUS = False
+# Interval the sensor publishes to Adafruit IO, in minutes
+PUBLISH_INTERVAL = 10
+
+### WiFi ###
+
+# Get wifi details and more from a secrets.py file
+try:
+    from secrets import secrets
+except ImportError:
+    print("WiFi secrets are kept in secrets.py, please add them there!")
+    raise
+
+# AirLift FeatherWing
+esp32_cs = DigitalInOut(board.D13)
+esp32_reset = DigitalInOut(board.D12)
+esp32_ready = DigitalInOut(board.D11)
+
+spi = busio.SPI(board.SCK, board.MOSI, board.MISO)
+esp = adafruit_esp32spi.ESP_SPIcontrol(spi, esp32_cs, esp32_ready, esp32_reset)
+status_light = neopixel.NeoPixel(board.NEOPIXEL, 1, brightness=0.2)
+wifi = adafruit_esp32spi_wifimanager.ESPSPI_WiFiManager(esp, secrets, status_light)
+
+# Connect to a PM2.5 sensor over UART
+uart = busio.UART(board.TX, board.RX, baudrate=9600)
+pm25 = adafruit_pm25.PM25_UART(uart)
+
+# Connect to a BME280 sensor over I2C
+i2c = busio.I2C(board.SCL, board.SDA)
+bme280 = adafruit_bme280.Adafruit_BME280_I2C(i2c)
+
+### Sensor Functions ###
+def calculate_aqi(pm_sensor_reading):
+    """Returns a calculated air quality index (AQI)
+    and category as a tuple.
+    NOTE: The AQI returned by this function should ideally be measured
+    using the 24-hour concentration average. Calculating a AQI without
+    averaging will result in higher AQI values than expected.
+    :param float pm_sensor_reading: Particulate matter sensor value.
+
+    """
+    # Check sensor reading using EPA breakpoint (Clow-Chigh)
+    if 0.0 <= pm_sensor_reading <= 12.0:
+        # AQI calculation using EPA breakpoints (Ilow-IHigh)
+        aqi_val = map_range(int(pm_sensor_reading), 0, 12, 0, 50)
+        aqi_cat = "Good"
+    elif 12.1 <= pm_sensor_reading <= 35.4:
+        aqi_val = map_range(int(pm_sensor_reading), 12, 35, 51, 100)
+        aqi_cat = "Moderate"
+    elif 35.5 <= pm_sensor_reading <= 55.4:
+        aqi_val = map_range(int(pm_sensor_reading), 36, 55, 101, 150)
+        aqi_cat = "Unhealthy for Sensitive Groups"
+    elif 55.5 <= pm_sensor_reading <= 150.4:
+        aqi_val = map_range(int(pm_sensor_reading), 56, 150, 151, 200)
+        aqi_cat = "Unhealthy"
+    elif 150.5 <= pm_sensor_reading <= 250.4:
+        aqi_val = map_range(int(pm_sensor_reading), 151, 250, 201, 300)
+        aqi_cat = "Very Unhealthy"
+    elif 250.5 <= pm_sensor_reading <= 350.4:
+        aqi_val = map_range(int(pm_sensor_reading), 251, 350, 301, 400)
+        aqi_cat = "Hazardous"
+    elif 350.5 <= pm_sensor_reading <= 500.4:
+        aqi_val = map_range(int(pm_sensor_reading), 351, 500, 401, 500)
+        aqi_cat = "Hazardous"
+    else:
+        print("Invalid PM2.5 concentration")
+        aqi_val = -1
+        aqi_cat = None
+    return aqi_val, aqi_cat
+
+
+def sample_aq_sensor():
+    """Samples PM2.5 sensor
+    over a 2.3 second sample rate.
+
+    """
+    aq_reading = 0
+    aq_samples = []
+
+    # initial timestamp
+    time_start = time.monotonic()
+    # sample pm2.5 sensor over 2.3 sec sample rate
+    while time.monotonic() - time_start <= 2.3:
+        try:
+            aqdata = pm25.read()
+            aq_samples.append(aqdata["pm25 env"])
+        except RuntimeError:
+            print("Unable to read from sensor, retrying...")
+            continue
+        # pm sensor output rate of 1s
+        time.sleep(1)
+    # average sample reading / # samples
+    for sample in range(len(aq_samples)):
+        aq_reading += aq_samples[sample]
+    aq_reading = aq_reading / len(aq_samples)
+    aq_samples.clear()
+    return aq_reading
+
+
+def read_bme280(is_celsius=False):
+    """Returns temperature and humidity
+    from BME280 environmental sensor, as a tuple.
+
+    :param bool is_celsius: Returns temperature in degrees celsius
+                            if True, otherwise fahrenheit.
+    """
+    humid = bme280.humidity
+    temp = bme280.temperature
+    if not is_celsius:
+        temp = temp * 1.8 + 32
+    return temperature, humid
+
+
+# Create an instance of the Adafruit IO HTTP client
+io = IO_HTTP(secrets["aio_user"], secrets["aio_key"], wifi)
+
+# Describes feeds used to hold Adafruit IO data
+feed_aqi = io.get_feed("air-quality-sensor.aqi")
+feed_aqi_category = io.get_feed("air-quality-sensor.category")
+feed_humidity = io.get_feed("air-quality-sensor.humidity")
+feed_temperature = io.get_feed("air-quality-sensor.temperature")
+
+# Set up location metadata from secrets.py file
+location_metadata = (secrets["latitude"], secrets["longitude"], secrets["elevation"])
+
+elapsed_minutes = 0
+prv_mins = 0
+
+while True:
+    try:
+        print("Fetching time...")
+        cur_time = io.receive_time()
+        print("Time fetched OK!")
+        # Hourly reset
+        if cur_time.tm_min == 0:
+            prv_mins = 0
+    except (ValueError, RuntimeError) as e:
+        print("Failed to fetch time, retrying\n", e)
+        wifi.reset()
+        wifi.connect()
+        continue
+
+    if cur_time.tm_min >= prv_mins:
+        print("%d min elapsed.." % elapsed_minutes)
+        prv_mins = cur_time.tm_min
+        elapsed_minutes += 1
+
+    if elapsed_minutes >= PUBLISH_INTERVAL:
+        print("Sampling AQI...")
+        aqi_reading = sample_aq_sensor()
+        aqi, aqi_category = calculate_aqi(aqi_reading)
+        print("AQI: %d" % aqi)
+        print("Category: %s" % aqi_category)
+
+        # temp and humidity
+        print("Sampling environmental sensor...")
+        temperature, humidity = read_bme280(USE_CELSIUS)
+        print("Temperature: %0.1f F" % temperature)
+        print("Humidity: %0.1f %%" % humidity)
+
+        # Publish all values to Adafruit IO
+        print("Publishing to Adafruit IO...")
+        try:
+            io.send_data(feed_aqi["key"], str(aqi), location_metadata)
+            io.send_data(feed_aqi_category["key"], aqi_category)
+            io.send_data(feed_temperature["key"], str(temperature))
+            io.send_data(feed_humidity["key"], str(humidity))
+            print("Published!")
+        except (ValueError, RuntimeError) as e:
+            print("Failed to send data to IO, retrying\n", e)
+            wifi.reset()
+            wifi.connect()
+            continue
+        # Reset timer
+        elapsed_minutes = 0
+    time.sleep(30)