WS2812 Module

Since Origin / Contributor Maintainer Source
2015-02-05 Till Klocke, Thomas Soëte Till Klocke ws2812.c

ws2812 is a library to handle ws2812-like led strips. It works at least on WS2812, WS2812b, APA104, SK6812 (RGB or RGBW).

The library uses UART1 routed on GPIO2 (Pin D4 on NodeMCU DEVKIT) to generate the bitstream. It can use UART0 routed to TXD0 as well to handle two led strips at the same time.

WARNING: In dual mode, you will loose access to the Lua's console through the serial port (it will be reconfigured to support WS2812-like protocol). If you want to keep access to Lua's console, you will have to use an other input channel like a TCP server (see example)

ws2812.init(mode)

Initialize UART1 and GPIO2, should be called once and before write(). Initialize UART0 (TXD0) too if ws2812.MODE_DUAL is set.

Parameters

  • mode (optional) either ws2812.MODE_SINGLE (default if omitted) or ws2812.MODE_DUAL. In ws2812.MODE_DUAL mode you will be able to handle two strips in parallel but will lose access to Lua's serial console as it shares the same UART and PIN.

Returns

nil

ws2812.write()

Send data to one or two led strip using its native format which is generally Green,Red,Blue for RGB strips and Green,Red,Blue,White for RGBW strips.

Syntax

ws2812.write(data1, [data2])

Parameters

  • data1 payload to be sent to one or more WS2812 like leds through GPIO2
  • data2 (optional) payload to be sent to one or more WS2812 like leds through TXD0 (ws2812.MODE_DUAL mode required)

Payload type could be: - nil nothing is done - string representing bytes to send - ws2812.buffer see Buffer module

Returns

nil

Example

ws2812.init()
ws2812.write(string.char(255, 0, 0, 255, 0, 0)) -- turn the two first RGB leds to green

ws2812.init()
ws2812.write(string.char(0, 0, 0, 255, 0, 0, 0, 255)) -- turn the two first RGBW leds to white

ws2812.init(ws2812.MODE_DUAL)
ws2812.write(string.char(255, 0, 0, 255, 0, 0), string.char(0, 255, 0, 0, 255, 0)) -- turn the two first RGB leds to green on the first strip and red on the second strip

ws2812.init(ws2812.MODE_DUAL)
ws2812.write(nil, string.char(0, 255, 0, 0, 255, 0)) -- turn the two first RGB leds to red on the second strip, do nothing on the first

Buffer module

For more advanced animations, it is useful to keep a "framebuffer" of the strip, interact with it and flush it to the strip.

For this purpose, the ws2812 library offers a read/write buffer.

Example

Led chaser with a RGBW strip

ws2812.init()
local i, buffer = 0, ws2812.newBuffer(300, 4); buffer:fill(0, 0, 0, 0); tmr.alarm(0, 50, 1, function()
        i=i+1
        buffer:fade(2)
        buffer:set(i%buffer:size()+1, 0, 0, 0, 255)
        ws2812.write(buffer)
end)

ws2812.newBuffer()

Allocate a new memory buffer to store led values.

Syntax

ws2812.newBuffer(numberOfLeds, bytesPerLed)

Parameters

  • numberOfLeds length of the led strip
  • bytesPerLed 3 for RGB strips and 4 for RGBW strips

Returns

ws2812.buffer

ws2812.buffer:get()

Return the value at the given position

Syntax

buffer:get(index)

Parameters

  • index position in the buffer (1 for first led)

Returns

(color)

Example

buffer = ws2812.newBuffer(32, 4)
print(buffer:get(1))
0   0   0   0

ws2812.buffer:set()

Set the value at the given position

Syntax

buffer:set(index, color)

Parameters

  • index position in the buffer (1 for the first led)
  • color payload of the color

Payload could be: - number, number, ... you should pass as many arguments as bytesPerLed - table should contains bytesPerLed numbers - string should contains bytesPerLed bytes

Returns

nil

Example

buffer = ws2812.newBuffer(32, 3)
buffer:set(1, 255, 0, 0) -- set the first led green for a RGB strip

buffer = ws2812.newBuffer(32, 4)
buffer:set(1, {0, 0, 0, 255}) -- set the first led white for a RGBW strip

buffer = ws2812.newBuffer(32, 3)
buffer:set(1, string.char(255, 0, 0)) -- set the first led green for a RGB strip

ws2812.buffer:size()

Return the size of the buffer in number of leds

Syntax

buffer:size()

Parameters

none

Returns

int

ws2812.buffer:fill()

Fill the buffer with the given color. The number of given bytes must match the number of bytesPerLed of the buffer

Syntax

buffer:fill(color)

Parameters

  • color bytes of the color, you should pass as many arguments as bytesPerLed

Returns

nil

Example

buffer:fill(0, 0, 0) -- fill the buffer with black for a RGB strip

ws2812.buffer:fade()

Fade in or out. Defaults to out. Multiply or divide each byte of each led with/by the given value. Useful for a fading effect.

Syntax

buffer:fade(value [, direction])

Parameters

  • value value by which to divide or multiply each byte
  • direction ws2812.FADE_IN or ws2812.FADE_OUT. Defaults to ws2812.FADE_OUT

Returns

nil

Example

buffer:fade(2)
buffer:fade(2, ws2812.FADE_IN)

ws2812.buffer:shift()

Shift the content of the buffer in positive or negative direction. This allows simple animation effects.

Syntax

buffer:shift(value [, mode])

Parameters

  • value number of pixels by which to rotate the buffer. Positive values rotate forwards, negative values backwards.
  • mode is the shift mode to use. Can be one of ws2812.SHIFT_LOGICAL or ws2812.SHIFT_CIRCULAR. In case of SHIFT_LOGICAL, the freed pixels are set to 0 (off). In case of SHIFT_CIRCULAR, the buffer is treated like a ring buffer, inserting the pixels falling out on one end again on the other end. Defaults to SHIFT_LOGICAL.

Returns

nil

Example

buffer:shift(3)