Added LED matrix example

Author: MarkAYoder

source/examples/python/i2cmatrix.py

@@ -0,0 +1,33 @@
+#!/usr/bin/env python3
+# Write an 8x8 Red/Green LED matrix
+# https://www.adafruit.com/product/902
+
+import smbus
+import time
+bus = smbus.SMBus(1)
+matrix = 0x70
+
+delay = 1; # Delay between images in s
+
+bus.write_byte_data(matrix, 0x21, 0)   # Start oscillator (p10)
+bus.write_byte_data(matrix, 0x81, 0)   # Disp on, blink off (p11)
+bus.write_byte_data(matrix, 0xe7, 0)   # Full brightness (page 15)
+
+# The first byte is GREEN, the second is RED.
+smile = [0x00, 0x3c, 0x00, 0x42, 0x28, 0x89, 0x04, 0x85,
+    0x04, 0x85, 0x28, 0x89, 0x00, 0x42, 0x00, 0x3c
+]
+frown = [0x3c, 0x00, 0x42, 0x00, 0x85, 0x20, 0x89, 0x00,
+    0x89, 0x00, 0x85, 0x20, 0x42, 0x00, 0x3c, 0x00
+]
+neutral = [0x3c, 0x3c, 0x42, 0x42, 0xa9, 0xa9, 0x89, 0x89,
+    0x89, 0x89, 0xa9, 0xa9, 0x42, 0x42, 0x3c, 0x3c
+]
+
+bus.write_i2c_block_data(matrix, 0, frown)
+time.sleep(delay)
+
+bus.write_i2c_block_data(matrix, 0, neutral)
+time.sleep(delay)
+
+bus.write_i2c_block_data(matrix, 0, smile)