add milk checker code

Author: caternuson

CLUE_Milk_Checker/bmps/milk_bg.bmp

@@ -0,0 +1,75 @@
+import time
+import board
+import terminalio
+import displayio
+import adafruit_sgp30
+from adafruit_bitmap_font import bitmap_font
+from adafruit_display_text import label
+import adafruit_imageload
+from adafruit_clue import clue
+
+#--| User Config |-------------------------
+TVOC_LEVELS = (80, 120) # set two TVOC levels
+MESSAGES = ("GOOD", "SUS?", "BAD!") # set three messages (4 char max)
+#------------------------------------------
+
+# setup UI
+cow_bmp, cow_pal = adafruit_imageload.load("bmps/milk_bg.bmp")
+background = displayio.TileGrid(cow_bmp, pixel_shader=cow_pal)
+
+mouth_bmp, mouth_pal = adafruit_imageload.load("bmps/mouth_sheet.bmp")
+mouth = displayio.TileGrid(mouth_bmp, pixel_shader=mouth_pal,
+    tile_width = 40,
+    tile_height = 20,
+    width = 1,
+    height = 1,
+    x = 35, y=110)
+
+msg_font = bitmap_font.load_font("fonts/Alphakind_28.bdf")
+msg_font.load_glyphs("".join(MESSAGES))
+message = label.Label(msg_font, text="WAIT", color=0x000000)
+message.anchor_point = (0.5, 0.5)
+message.anchored_position = (172, 38)
+
+data_font = bitmap_font.load_font("fonts/F25_Bank_Printer_Bold_12.bdf")
+data_font.load_glyphs("eTVOC=12345?")
+tvoc = label.Label(data_font, text="TVOC=?????", color=0x000000)
+tvoc.anchor_point = (0, 1)
+tvoc.anchored_position = (5, 235)
+
+eco2 = label.Label(data_font, text="eCO2=?????", color=0x000000)
+eco2.anchor_point = (0, 1)
+eco2.anchored_position = (130, 235)
+
+splash = displayio.Group(max_size=5)
+splash.append(background)
+splash.append(mouth)
+splash.append(message)
+splash.append(tvoc)
+splash.append(eco2)
+clue.display.show(splash)
+
+# setup SGP30 and wait for initial warm up
+sgp30 = adafruit_sgp30.Adafruit_SGP30(board.I2C())
+time.sleep(15)
+
+# loop forever
+while True:
+    eCO2, TVOC = sgp30.iaq_measure()
+
+    tvoc.text = "TVOC={:5d}".format(TVOC)
+    eco2.text = "eCO2={:5d}".format(eCO2)
+
+    level = 0
+    for thresh in TVOC_LEVELS:
+        if TVOC <= thresh:
+            break
+        level += 1
+
+    if level <= len(TVOC_LEVELS):
+        message.text = MESSAGES[level]
+        mouth[0] = level
+    else:
+        message.text = "????"
+
+    time.sleep(1)