Wemos WS2812 and OLED

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Aug 132016
 

It was surprisingly difficult to find some working nodeMCU examples. Thus here my findings and sample code:

First the WS2812 shield: It’s using D2 (NodeMCU numbering, which is printed on the board). The ws2812 module for NodeMCU uses D4 though. Here what it looks like:

Wemos-WS2812-modified

With this change, this sample program works:

ws2812.init()
ws2812.write(string.char(100, 20, 5))

Green 100, Red 20, Blue 5. GRB.

The OLED shield needs no hardware modification, but it’s using non-standard I²C pins it seems. Here a working example (using a very slightly modified https://github.com/nodemcu/nodemcu-firmware/blob/master/lua_examples/u8glib/u8g_graphics_test.lua).

I removed the SPI parts, adjusted the pins. The rest is unmodified:

-- ***************************************************************************
-- Rotation Test
--
-- This script executes the rotation features of u8glib to test their Lua
-- integration.
--
-- Note: It is prepared for SSD1306-based displays. Select your connectivity
-- type by calling either init_i2c_display() or init_spi_display() at
-- the bottom of this file.
--
-- ***************************************************************************

-- setup I2c and connect display
function init_i2c_display()
 -- SDA and SCL can be assigned freely to available GPIOs
 local sda = 2 -- 5 -- GPIO14
 local scl = 1 -- 6 -- GPIO12
 local sla = 0x3c
 i2c.setup(0, sda, scl, i2c.SLOW)
 disp = u8g.ssd1306_64x48_i2c(sla)
end


-- the draw() routine
function draw()
 disp:setFont(u8g.font_6x10)
 
 disp:drawStr( 0+0, 20+0, "Hello!")
 disp:drawStr( 0+2, 20+16, "Hello!")

 disp:drawBox(0, 0, 3, 3)
 disp:drawBox(disp:getWidth()-6, 0, 6, 6)
 disp:drawBox(disp:getWidth()-9, disp:getHeight()-9, 9, 9)
 disp:drawBox(0, disp:getHeight()-12, 12, 12)
end


function rotate()
 if (next_rotation < tmr.now() / 1000) then
  if (dir == 0) then
   disp:undoRotation()
  elseif (dir == 1) then
   disp:setRot90()
  elseif (dir == 2) then
   disp:setRot180()
  elseif (dir == 3) then
   disp:setRot270()
  end

  dir = dir + 1
  dir = bit.band(dir, 3)
  -- schedule next rotation step in 1000ms
  next_rotation = tmr.now() / 1000 + 1000
 end
end

function rotation_test()
 print("--- Starting Rotation Test ---")
 dir = 0
 next_rotation = 0
 print("size:", disp:getWidth(), disp:getHeight())
 local loopcnt
 for loopcnt = 1, 100, 1 do
  rotate()

  disp:firstPage()
  repeat
    draw()
  until disp:nextPage() == false

  tmr.delay(100000)
  tmr.wdclr()
  end

 print("--- Rotation Test done ---")
end

init_i2c_display()
rotation_test()

The important bits: SDA=2, SCL=1, ADDR=0x3C (there’s a jumper to change it to 0x3D if needed)