Getting started¶

LEDs¶

Ok, this is a library to manipulate leds. So, you definitly need leds. The arduino sketch makes use of the fastled library. I only used WS2812B led stripes, but any led type supported by the library should work. If you’re using any other led, you may need to tweak the sketch to initialize fastled correctly. For more details on fastled it is worth checking out the website Fastled.io. There you will also find some useful information about timings and power consumtion.

A micro controller¶

The correct sketch depends on the way you want to communicate with the controller. A sketch counterparts a certain sender class. Currently two sketches are available. One for the UDPSender class and one for the SerialSender class.

Here I will focus on the serial communication. The sketch you need is the Framebuffer3.ino sketch.

#include <Arduino.h>
#include <FastLED.h>

#define DATA_PIN              5
#define BAUDRATE         500000
#define MAX_SERIAL_DELAY   3000  // Maximum delay between transmitted
                                 // data within one command in milliseconds

#define BYTES_PER_PIXEL      3
#define CMD_PAINT_PANEL    243

#define NODEBUG

const uint8_t numberOfLeds  = 100;
const int16_t numberOfByte = numberOfLeds * BYTES_PER_PIXEL;

Before uploading the script, some adjustments have to be done to match your setup.

The Data Pin¶

The pin on the micro controller, where the data line of your leds is connected to. The default is pin 5.

The Baudrate¶

The baudrate for the serial communication. The baudrate in the sketch and the baudrate in the constructor of the SerialSender have to be identical. Please read the documentation of the PySerial module, as not all speeds are supported on every plattform. Some people reported, that you have to change boot settings on the raspberry before using higher speeds than 155200 b/s. On my raspberry 3 the default speed of 0,5 Mb/s worked perfectly. Keep in mind, that also the quality and the length of the usb cable will have an impact.

The Number of Leds¶

The variable numberOfLeds holds (surprise, surprise) the number of LEDs on your panel.

Warning

Make shure you don’t use more leds in your python Display instance. Also make shure that your physical board doesn’t have less leds.

Installing the python library¶

Writing your first script¶

You can fire up the python3 REPL console or use your favorite editor or ide.

Tip

The library supports only python 3. Scripts will not run with python 2.

The Hello World of LEDWall¶

import ledwall.components as comp

s = comp.SerialSender()            # Creating a serial sender with the
                                   # default port_name and baudrate
d = comp.Display(16,32,s)          # Defining a new display component

red   = comp.Color(255,0,0)        # Defining an RGB color
col   = comp.HSVColor(0.7,0.8,1.0) # Defining an HSVColor

d.fill((0,255,0))                  # Fill the panel with green. You can specify
                                   # rgb colors as tuple as you go
d.set_pixel(0,3,red)               # which is equivalent to:
                                   # d[(0,3)] = red or d[(0,3)] = (255,0,0)
d.set_pixel(14,23,col)             # Setting the pixel to the defined
                                   # hsv color. Comversion to rgb is calculated
                                   # on the fly

col.hue += 0.13                    # Changing the HUE component of the color
d.set_pixel(15,23,col)             # Setting the pixel in this color

d.update()                         # Updating the physical component