WS2812 driver

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Python driver for controlling WS2812(B) or any comparable RGB adressable LED strip over I2S bus.

For all platforms (NanoPi, RPi, etc.) make sure your system is able to compile Python extensions. On your OS (Armbian, Raspbian, Ubuntu, etc.) ensure your system is ready by executing:

sudo apt-get update
sudo apt-get install gcc python3-dev libasound2-dev

Overview

This repository includes a python code needed to build an LED strip scale thermometer:

This code for visualization includes functions:

  • scale thermometer
  • demo trail

Prerequisites

This project is based on I2S bus, so use DOUT pin of I2S bus on your device. Before you run code, you should make sure that you work with:

  • Linux embedded platform (recommended Armbian 5.30 stable Ubuntu 16.04.2)
  • ws2812b addressable led strip (of any size)
  • 5V power supply (recommended)

Python Dependencies

Compatible with Python 3.5 (including pyalsaaudio package).

  • Tested on Debian-based Armbian (Armbian 5.30 stable Ubuntu 16.04.2).
  • Linux kernel version at least 3.4.113

Installing dependencies

You will need to set up a I2S device with following commands:

cd /boot
sudo bin2fex script.bin script.fex
sudo nano script.fex

In next step change following attributes in script:

[twi1]
twi_used = 0

[pcm0]
daudio_used = 1
sample_resolution = 16
slot_width_select = 16
pcm_lrck_period = 16
slot_width = 16

Save your changes and convert file again:

sudo fex2bin script.fex script.bin

Reboot your device. After reboot try command:

aplay -l

It looks like:

**** List of PLAYBACK Hardware Devices ****
card 0: audiocodec [audiocodec], device 0: SUNXI-CODEC sndcodec-0 []
Subdevices: 1/1
Subdevice #0: subdevice #0
card 1: snddaudio [snddaudio], device 0: SUNXI-TDM0 snddaudio-0 []
Subdevices: 1/1
Subdevice #0: subdevice #0
card 2: sndhdmi [sndhdmi], device 0: SUNXI-HDMIAUDIO sndhdmi-0 []
Subdevices: 1/1
Subdevice #0: subdevice #0

“card 1” is the one we want.

Demo trail

  • Function show_animation will display fast moving trail.

Scale thermometer

  • Function meas_temperature sets up led string as a thermometer or scale display.
  • As arguments you have to define number of leds, minimum, maximum and actual temperature.
def meas_temperature(num_leds, min_temp, max_temp, temp, bright=100, heatmap=None, reverse=None)
  • Optional arguments are brigtness, your own-defined heatmap and reverse mode
heatmap = [(0,   100,  (0, 0, 256)),
           (400, 500,  (0, 256, 0)),
           (900, 1000, (256, 0, 0))]
  • You can define heatmap with fixed limits for each color e.g. (0, 150, (10, 256, 20). Coulours among are set transiently.

Credits

This package was created with Cookiecutter and the audreyr/cookiecutter-pypackage project template.