adafruit_neopixels.py

import time
 
import Adafruit_GPIO as GPIO
import Adafruit_GPIO.FT232H as FT232H
 
 
class NeoPixel_FT232H(object):
	def __init__(self, n):
		# Create an FT232H object.
		self.ft232h = FT232H.FT232H()
		# Create a SPI interface for the FT232H object.  Set the SPI bus to 6mhz.
		self.spi    = FT232H.SPI(self.ft232h, max_speed_hz=6000000)
		# Create a pixel data buffer and lookup table.
		self.buffer = bytearray(n*24)
		self.lookup = self.build_byte_lookup()
 
	def build_byte_lookup(self):
		# Create a lookup table to map all byte values to 8 byte values which
		# represent the 6mhz SPI data to generate the NeoPixel signal for the
		# specified byte.
		lookup = {}
		for i in range(256):
			value = bytearray()
			for j in range(7, -1, -1):
				if ((i >> j) & 1) == 0:
					value.append(0b11100000)
				else:
					value.append(0b11111000)
			lookup[i] = value
		return lookup
 
	def set_pixel_color(self, n, r, g, b):
		# Set the pixel RGB color for the pixel at position n.
		# Assumes GRB NeoPixel color ordering, but it's easy to change below.
		index = n*24
		self.buffer[index   :index+8 ] = self.lookup[int(g)]
		self.buffer[index+8 :index+16] = self.lookup[int(r)]
		self.buffer[index+16:index+24] = self.lookup[int(b)]
 
	def show(self):
		# Send the pixel buffer out the SPI data output pin (D1) as a NeoPixel
		# signal.
		self.spi.write(self.buffer)
 
 
# Run this code when the script is called at the command line:
if __name__ == '__main__':
	# Define the number of pixels in the NeoPixel strip.
	# Only up to ~340 pixels can be written using the FT232H.
	pixel_count = 16
	# Create a NeoPixel_FT232H object.
	pixels = NeoPixel_FT232H(pixel_count)
	# Animate each pixel turning red.
	# Loop through each pixel.
	for i in range(pixel_count):
		# Set the pixel color to pure red.
		pixels.set_pixel_color(i, 255, 0, 0)
		# Show the pixel buffer by sending it to the LEDs.
		pixels.show()
		# Delay for a short period of time.
		time.sleep(0.25)
	# Animate each pixel turning pure green.
	for i in range(pixel_count):
		pixels.set_pixel_color(i, 0, 255, 0)
		pixels.show()
		time.sleep(0.25)
	# Animate each pixel turning pure blue.
	for i in range(pixel_count):
		pixels.set_pixel_color(i, 0, 0, 255)
		pixels.show()
		time.sleep(0.25)
	# Animate a pattern of colors marching around the pixels.
	# Create a pattern of colors to display.
	colors = [ (255, 0, 0), (255, 255, 0), (0, 255, 0), (0, 255, 255), 
				(0, 0, 255), (255, 0, 255) ]
	offset = 0
	print 'Press Ctrl-C to quit.'
	while True:
		# Loop through all the pixels and set their color based on the pattern.
		for i in range(pixel_count):
			color = colors[(i+offset)%len(colors)]
			pixels.set_pixel_color(i, color[0], color[1], color[2])
		pixels.show()
		# Increase the offset to make the colors change position.
		offset += 1
		time.sleep(0.25)