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Purple_Air_Display/purple_air_display.py

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+# Purple Air AQI Display
+# for Metro M4 Airlift with RGB Matrix Shield
+# or Matrix Portal
+# and 64 x 32 RGB LED Matrix
+
+import time
+import board
+import terminalio
+from adafruit_matrixportal.matrixportal import MatrixPortal
+
+def aqi_transform(val):
+    aqi = pm_to_aqi(val)  # derive Air Quality Index from Particulate Matter 2.5 value
+    return "AQI: %d" % aqi
+
+def message_transform(val):  # picks message based on thresholds
+    index = aqi_to_list_index(pm_to_aqi(val))
+    messages = (
+        "Hazardous",
+        "Very Unhealthy",
+        "Unhealthy",
+        "Unhealthy for Sensitive Groups",
+        "Moderate",
+        "Good",
+    )
+
+    if index is not None:
+        return messages[index]
+    return "Unknown"
+
+SENSOR_ID = 3085 # Poughkeepsie  # 30183  LA outdoor  / 37823  oregon  / 21441   NYC
+SENSOR_REFRESH_PERIOD = 30  # seconds
+DATA_SOURCE = "https://www.purpleair.com/json?show=" + str(SENSOR_ID)
+SCROLL_DELAY = 0.02
+DATA_LOCATION = ["results", 0, "PM2_5Value"]  # navigate the JSON response
+
+# --- Display setup ---
+matrixportal = MatrixPortal(
+    status_neopixel=board.NEOPIXEL,
+    debug=True,
+    url=DATA_SOURCE,
+    json_path=(DATA_LOCATION, DATA_LOCATION),
+)
+
+# Create a static label to show AQI
+matrixportal.add_text(
+    text_font=terminalio.FONT,
+    text_position=(8, 7),
+    text_transform=aqi_transform,
+)
+
+# Create a scrolling label to show level message
+matrixportal.add_text(
+    text_font=terminalio.FONT,
+    text_position=(0, 23),
+    scrolling=True,
+    text_transform=message_transform,
+)
+# pylint: disable=too-many-return-statements
+def aqi_to_list_index(aqi):
+    aqi_groups = (301, 201, 151, 101, 51, 0)
+    for index, group in enumerate(aqi_groups):
+        if aqi >= group:
+            return index
+    return None
+
+def calculate_aqi(Cp, Ih, Il, BPh, BPl):  # wikipedia.org/wiki/Air_quality_index#Computing_the_AQI
+    return round(((Ih - Il)/(BPh - BPl)) * (Cp - BPl) + Il)
+
+def pm_to_aqi(pm):
+    pm = float(pm)
+    if pm < 0:
+        return pm
+    if pm > 1000:
+        return 1000
+    if pm > 350.5:
+        return calculate_aqi(pm, 500, 401, 500, 350.5)
+    elif pm > 250.5:
+        return calculate_aqi(pm, 400, 301, 350.4, 250.5)
+    elif pm > 150.5:
+        return calculate_aqi(pm, 300, 201, 250.4, 150.5)
+    elif pm > 55.5:
+        return calculate_aqi(pm, 200, 151, 150.4, 55.5)
+    elif pm > 35.5:
+        return calculate_aqi(pm, 150, 101, 55.4, 35.5)
+    elif pm > 12.1:
+        return calculate_aqi(pm, 100, 51, 35.4, 12.1)
+    elif pm >= 0:
+        return calculate_aqi(pm, 50, 0, 12, 0)
+    else:
+        return None
+
+def get_color(aqi):
+    index = aqi_to_list_index(aqi)
+    colors = (
+        (115, 20, 37),
+        (140, 26, 75),
+        (234, 51, 36),
+        (239, 133, 51),
+        (255, 255, 85),
+        (104, 225, 67),
+    )
+    if index is not None:
+        return colors[index]
+    return (150, 150, 150)
+
+sensor_refresh = None
+while True:
+    # only query the weather every 10 minutes (and on first run)
+    if (not sensor_refresh) or (time.monotonic() - sensor_refresh) > SENSOR_REFRESH_PERIOD:
+        try:
+            value = matrixportal.fetch()
+            print("Response is", value)
+            matrixportal.set_text_color(get_color(pm_to_aqi(value[0])))
+            sensor_refresh = time.monotonic()
+        except RuntimeError as e:
+            print("Some error occured, retrying! -", e)
+            continue
+
+    # Scroll it
+    matrixportal.scroll_text(SCROLL_DELAY)