Add mics6814 python demo

micropython/examples/breakout_mics6814/mics6814_demo.py

@@ -0,0 +1,54 @@
+import time
+from breakout_mics6814 import BreakoutMICS6814
+
+OUTPUT_FREQUENCY = 0.5
+
+gas = BreakoutMICS6814()
+
+gas.set_brightness(1.0)
+
+
+# From CPython Lib/colorsys.py
+def hsv_to_rgb(h, s, v):
+    if s == 0.0:
+        return v, v, v
+    i = int(h * 6.0)
+    f = (h * 6.0) - i
+    p = v * (1.0 - s)
+    q = v * (1.0 - s * f)
+    t = v * (1.0 - s * (1.0 - f))
+    i = i % 6
+    if i == 0:
+        return v, t, p
+    if i == 1:
+        return q, v, p
+    if i == 2:
+        return p, v, t
+    if i == 3:
+        return p, q, v
+    if i == 4:
+        return t, p, v
+    if i == 5:
+        return v, p, q
+
+
+h = 0
+
+last_output = time.time()
+
+while True:
+    oxd = gas.read_oxidising()
+    red = gas.read_reducing()
+    nh3 = gas.read_nh3()
+
+    r, g, b = [int(255 * c) for c in hsv_to_rgb(h / 360.0, 1.0, 1.0)]  # rainbow magic
+
+    if time.time() - last_output > OUTPUT_FREQUENCY:
+        print("OX: {} Red: {} NH3: {}".format(oxd, red, nh3))
+        last_output = time.time()
+
+    gas.set_led(r, g, b)
+
+    h += 1
+
+    time.sleep(0.02)