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99 lines
3.7 KiB
99 lines
3.7 KiB
# Example of low-level Python wrapper for rpi_ws281x library.
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# Author: Tony DiCola (tony@tonydicola.com), Jeremy Garff (jer@jers.net)
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#
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# This is an example of how to use the SWIG-generated _rpi_ws281x module.
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# You probably don't want to use this unless you are building your own library,
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# because the SWIG generated module is clunky and verbose. Instead look at the
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# high level Python port of Adafruit's NeoPixel Arduino library in strandtest.py.
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#
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# This code will animate a number of WS281x LEDs displaying rainbow colors.
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import time
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import _rpi_ws281x as ws
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# LED configuration.
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LED_CHANNEL = 0
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LED_COUNT = 16 # How many LEDs to light.
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LED_FREQ_HZ = 800000 # Frequency of the LED signal. Should be 800khz or 400khz.
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LED_DMA_NUM = 10 # DMA channel to use, can be 0-14.
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LED_GPIO = 18 # GPIO connected to the LED signal line. Must support PWM!
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LED_BRIGHTNESS = 255 # Set to 0 for darkest and 255 for brightest
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LED_INVERT = 0 # Set to 1 to invert the LED signal, good if using NPN
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# transistor as a 3.3V->5V level converter. Keep at 0
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# for a normal/non-inverted signal.
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# Define colors which will be used by the example. Each color is an unsigned
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# 32-bit value where the lower 24 bits define the red, green, blue data (each
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# being 8 bits long).
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DOT_COLORS = [ 0x200000, # red
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0x201000, # orange
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0x202000, # yellow
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0x002000, # green
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0x002020, # lightblue
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0x000020, # blue
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0x100010, # purple
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0x200010 ] # pink
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# Create a ws2811_t structure from the LED configuration.
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# Note that this structure will be created on the heap so you need to be careful
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# that you delete its memory by calling delete_ws2811_t when it's not needed.
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leds = ws.new_ws2811_t()
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# Initialize all channels to off
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for channum in range(2):
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channel = ws.ws2811_channel_get(leds, channum)
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ws.ws2811_channel_t_count_set(channel, 0)
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ws.ws2811_channel_t_gpionum_set(channel, 0)
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ws.ws2811_channel_t_invert_set(channel, 0)
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ws.ws2811_channel_t_brightness_set(channel, 0)
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channel = ws.ws2811_channel_get(leds, LED_CHANNEL)
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ws.ws2811_channel_t_count_set(channel, LED_COUNT)
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ws.ws2811_channel_t_gpionum_set(channel, LED_GPIO)
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ws.ws2811_channel_t_invert_set(channel, LED_INVERT)
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ws.ws2811_channel_t_brightness_set(channel, LED_BRIGHTNESS)
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ws.ws2811_t_freq_set(leds, LED_FREQ_HZ)
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ws.ws2811_t_dmanum_set(leds, LED_DMA_NUM)
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# Initialize library with LED configuration.
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resp = ws.ws2811_init(leds)
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if resp != ws.WS2811_SUCCESS:
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message = ws.ws2811_get_return_t_str(resp)
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raise RuntimeError('ws2811_init failed with code {0} ({1})'.format(resp, message))
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# Wrap following code in a try/finally to ensure cleanup functions are called
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# after library is initialized.
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try:
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offset = 0
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while True:
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# Update each LED color in the buffer.
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for i in range(LED_COUNT):
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# Pick a color based on LED position and an offset for animation.
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color = DOT_COLORS[(i + offset) % len(DOT_COLORS)]
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# Set the LED color buffer value.
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ws.ws2811_led_set(channel, i, color)
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# Send the LED color data to the hardware.
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resp = ws.ws2811_render(leds)
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if resp != ws.WS2811_SUCCESS:
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message = ws.ws2811_get_return_t_str(resp)
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raise RuntimeError('ws2811_render failed with code {0} ({1})'.format(resp, message))
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# Delay for a small period of time.
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time.sleep(0.25)
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# Increase offset to animate colors moving. Will eventually overflow, which
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# is fine.
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offset += 1
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finally:
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# Ensure ws2811_fini is called before the program quits.
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ws.ws2811_fini(leds)
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# Example of calling delete function to clean up structure memory. Isn't
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# strictly necessary at the end of the program execution here, but is good practice.
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ws.delete_ws2811_t(leds)
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