Add rgb led example (#67)

* Adding helper methods (toRed, toGreen, toBlue) for hex-encoded color feeds
* Adding example for AIO Basics: Color

Adafruit_IO/client.py

@@ -211,6 +211,21 @@ class Client(object):
         """
         path = "feeds/{0}/data/{1}".format(feed, data_id)
         self._delete(path)
+    
+    def toRed(self, data):
+        """Hex color feed to red channel. 
+        """
+        return ((int(data[1], 16))*16) + int(data[2], 16)
+    
+    def toGreen(self, data):
+        """Hex color feed to green channel. 
+        """
+        return (int(data[3], 16) * 16) + int(data[4], 16)
+
+    def toBlue(self, data):
+        """Hex color feed to blue channel. 
+        """
+        return (int(data[5], 16) * 16) + int(data[6], 16)
 
     # Feed functionality.
     def feeds(self, feed=None):

Adafruit_IO/mqtt_client.py

@@ -147,7 +147,7 @@ class MQTTClient(object):
         Params:
         - stop: boolean, stops the execution of the background loop.
         """
-        is stop:
+        if stop:
             self._client.loop_stop()
         self._client.loop_start()
 

examples/basics/rgb_led.py

@@ -0,0 +1,85 @@
+"""
+`rgb_led.py`
+------------------------
+Control a RGB LED using
+Adafruit IO and Python
+
+Requires:
+    - Adafruit-Blinka
+    - Adafruit-CircuitPython-PCA9685
+"""
+# import system libraries
+import time
+
+# import Adafruit Blinka
+from board import SCL, SDA
+from busio import I2C
+
+# import the PCA9685 module.
+from adafruit_pca9685 import PCA9685
+
+# import Adafruit IO REST client
+from Adafruit_IO import Client, Feed, RequestError
+
+# PWM Pins
+RED_PIN = 6
+GREEN_PIN = 5
+BLUE_PIN = 4
+
+# Set to your Adafruit IO key.
+# Remember, your key is a secret,
+# so make sure not to publish it when you publish this code!
+ADAFRUIT_IO_KEY = 'YOUR_AIO_KEY'
+
+# Set to your Adafruit IO username.
+# (go to https://accounts.adafruit.com to find your username)
+ADAFRUIT_IO_USERNAME = 'YOUR_AIO_USERNAME'
+
+# Create an instance of the REST client.
+aio = Client(ADAFRUIT_IO_USERNAME, ADAFRUIT_IO_KEY)
+
+try: # if we have a 'color' feed
+    color = aio.feeds('color')
+except RequestError: # create an `color` feed
+    feed = Feed(name='color')
+    color = aio.create_feed(feed)
+
+# Create the I2C bus interface.
+i2c_bus = I2C(SCL, SDA)
+
+# Create a simple PCA9685 class instance.
+pca = PCA9685(i2c_bus)
+pca.frequency = 60
+prev_color = '#000000'
+
+def map_range(x, in_min, in_max, out_min, out_max):
+    """re-maps a number from one range to another."""
+    mapped = (x-in_min) * (out_max - out_min) / (in_max-in_min) + out_min
+    if out_min <= out_max:
+        return max(min(mapped, out_max), out_min)
+    return min(max(mapped, out_max), out_min)
+
+while True:
+    # grab the `color` feed
+    color_val = aio.receive(color.key)
+    if color_val != prev_color:
+        # print rgb values and hex value
+        print('Received Color: ')
+        red = aio.toRed(color_val.value)
+        print('\t - R: ', red)
+        green = aio.toGreen(color_val.value)
+        print('\t - G: ', green)
+        blue = aio.toBlue(color_val.value)
+        print('\t - B: ', blue)
+        print('\t - HEX: ', color_val.value)
+        # map color values (0-255) to  16-bit values for the pca
+        red = map_range(int(red), 0, 255, 0, 65535)
+        green = map_range(int(green), 0, 255, 0, 65535)
+        blue = map_range(int(blue), 0, 255, 0, 65535)
+        # invert RGB values for common anode LEDs.
+        pca.channels[RED_PIN].duty_cycle = 65535 - int(red)
+        pca.channels[GREEN_PIN].duty_cycle = 65535 - int(green)
+        pca.channels[BLUE_PIN].duty_cycle = 65535 - int(blue)
+    prev_color = color_val
+    # let's wait a bit so we don't flood adafruit io's servers...
+    time.sleep(1)