Brian Daniels / Mbed 2 deprecated WS2812_Example

Example for WS2812 Library

Dependencies:   PixelArray WS2812 mbed

Dependents:   Button_Neopixel

This is a demo for the WS2812 LED driver library.

The the timings of the bit banging operation are very sensitive. Depending on the platform, you will need to change the timing values in the WS2812 constructor. The default values in this demo are for the K64F. Here are a few other values for other platforms:

K64F, KL46Z: 0, 5, 5, 0

LPC1768: 5, 10, 10, 15

NUCLEO F411RE: 7, 15, 10, 15

UPDATE 11-29-2016

Thanks to the user Proff for the new measurements!

LPC1768: 3, 11, 10, 11

NUCLEO_F401RE: 3, 12, 9, 12

UPDATE 3-14-2017

Thanks to the user SashaK for the new measurements

NUCELO_F746ZG: 32, 105, 70, 123

If you are curious how to determine these values, see the WS2812 library page below.

Import libraryWS2812

Library for the WS2812 LED Driver. Uses bit banging and nops for precise timing. Number of nops executed are configurable at run time.

Last commit 12 Feb 2015 by Brian Daniels

.

main.cpp

Committer:
bridadan
Date:
2015-02-12
Revision:
2:cb82a3dc4031
Parent:
1:e04a0ecefa29

File content as of revision 2:cb82a3dc4031:

#include "mbed.h"
#include "WS2812.h"
#include "PixelArray.h"

#define WS2812_BUF 150
#define NUM_COLORS 6
#define NUM_LEDS_PER_COLOR 10

PixelArray px(WS2812_BUF);

// See the program page for information on the timing numbers
// The given numbers are for the K64F
WS2812 ws(D9, WS2812_BUF, 0, 5, 5, 0);

int main()
{

    ws.useII(WS2812::PER_PIXEL); // use per-pixel intensity scaling
    
    // set up the colours we want to draw with
    int colorbuf[NUM_COLORS] = {0x2f0000,0x2f2f00,0x002f00,0x002f2f,0x00002f,0x2f002f};

    // for each of the colours (j) write out 10 of them
    // the pixels are written at the colour*10, plus the colour position
    // all modulus 60 so it wraps around
    for (int i = 0; i < WS2812_BUF; i++) {
        px.Set(i, colorbuf[(i / NUM_LEDS_PER_COLOR) % NUM_COLORS]);
    }

    // now all the colours are computed, add a fade effect using intensity scaling
    // compute and write the II value for each pixel
    for (int j=0; j<WS2812_BUF; j++) {
        // px.SetI(pixel position, II value)
        px.SetI(j%WS2812_BUF, 0xf+(0xf*(j%NUM_LEDS_PER_COLOR)));
    }


    // Now the buffer is written, rotate it
    // by writing it out with an increasing offset
    while (1) {
        for (int z=WS2812_BUF; z >= 0 ; z--) {
            ws.write_offsets(px.getBuf(),z,z,z);
            wait(0.075);
        }
    }

}