add usage example

Author: mrmcwethy

README.rst

@@ -34,7 +34,42 @@ This is easily achieved by downloading
 Usage Example
 =============
 
-TODO
+```
+import busio
+import digitalio
+from board import SCK, MOSI, MISO, GPIO0, GPIO15
+
+from adafruit_rgb_display import color565
+import adafruit_rgb_display.ili9341 as ili9341
+
+
+# Configuratoin for CS and DC pins (these are FeatherWing defaults on ESP8266):
+CS_PIN = GPIO0
+DC_PIN = GPIO15
+# Config for display baudrate (default is 32mhz, about as fast as the ESP supports):
+BAUDRATE = 32000000
+
+
+# Setup SPI bus using hardware SPI:
+spi = busio.SPI(clock=SCK, MOSI=MOSI, MISO=MISO)
+
+# Create the ILI9341 display:
+display = ili9341.ILI9341(spi, cs=digitalio.DigitalInOut(CS_PIN),
+                          dc=digitalio.DigitalInOut(DC_PIN), baudrate=BAUDRATE)
+
+# Main loop:
+while True:
+    # Clear the display
+    display.fill(0)
+    # Draw a red pixel in the center.
+    display.pixel(120, 160, color565(255, 0, 0))
+    # Pause 2 seconds.
+    time.sleep(2)
+    # Clear the screen blue.
+    display.fill(color565(0, 0, 255))
+    # Pause 2 seconds.
+time.sleep(2)
+```
 
 API Reference
 =============