strandtest.py

#!/usr/bin/python

# Simple strand test for Adafruit Dot Star RGB LED strip.
# This is a basic diagnostic tool, NOT a graphics demo...helps confirm
# correct wiring and tests each pixel's ability to display red, green
# and blue and to forward data down the line.  By limiting the number
# and color of LEDs, it's reasonably safe to power a couple meters off
# USB.  DON'T try that with other code!

import time
from dotstar import Adafruit_DotStar

numpixels = 30 # Number of LEDs in strip

# Here's how to control the strip from any two GPIO pins:
datapin  = 23
clockpin = 24
strip    = Adafruit_DotStar(numpixels, datapin, clockpin)

# Alternate ways of declaring strip:
#  Adafruit_DotStar(npix, dat, clk, 1000000) # Bitbang @ ~1 MHz
#  Adafruit_DotStar(npix)                    # Use SPI (pins 10=MOSI, 11=SCLK)
#  Adafruit_DotStar(npix, 32000000)          # SPI @ ~32 MHz
#  Adafruit_DotStar()                        # SPI, No pixel buffer
#  Adafruit_DotStar(32000000)                # 32 MHz SPI, no pixel buf
# See image-pov.py for explanation of no-pixel-buffer use.
# Append "order='gbr'" to declaration for proper colors w/older DotStar strips)

strip.begin()           # Initialize pins for output
strip.setBrightness(64) # Limit brightness to ~1/4 duty cycle

# Runs 10 LEDs at a time along strip, cycling through red, green and blue.
# This requires about 200 mA for all the 'on' pixels + 1 mA per 'off' pixel.

head  = 0               # Index of first 'on' pixel
tail  = -10             # Index of last 'off' pixel
color = 0xFF0000        # 'On' color (starts red)

while True:                              # Loop forever

	strip.setPixelColor(head, color) # Turn on 'head' pixel
	strip.setPixelColor(tail, 0)     # Turn off 'tail'
	strip.show()                     # Refresh strip
	time.sleep(1.0 / 50)             # Pause 20 milliseconds (~50 fps)

	head += 1                        # Advance head position
	if(head >= numpixels):           # Off end of strip?
		head    = 0              # Reset to start
		color >>= 8              # Red->green->blue->black
		if(color == 0): color = 0xFF0000 # If black, reset to red

	tail += 1                        # Advance tail position
	if(tail >= numpixels): tail = 0  # Off end? Reset