ESP8266 / Hardware / IOT / nodemcu

ESP8266 OLED Example

by htladmin · Published November 30, 2015 · Updated November 30, 2015

OLED Displays are great in many ways. They use very little power, are bright, easy to read with large viewing angle and have high resolution considering their small size.
The OLED we will use today is .96″ inch in size, features 128×64 pixels and uses the SPI Bus.
We will use the u8glib library to communicate with our display. This library has many available parameters, we will use some of them to display a bitmap image and to display some text.
If you would like to experiment and learn more about this library, you can go to the Wiki: U8GLIB Wiki.
In this tutorial we will use the ESP8266 Wifi Module SSD1306 based OLED Display.
Our OLED display uses the SPI Bus.
Since the SPI Bus is faster than I2C, this will make our display very responsive.
Of course there’s a tradeoff, the SPI Bus uses more pins on our ESP8266

Pinout of our OLED Display

GND – Ground
VCC – Power 2.8V to 5.5V
D0 – Clock
D1 – Data
Res – Reset
DC – Data/Command
CS – Chip Select

Connect the OLED to the esp8266 Module

GND = GND
VCC = 3.3V
Hardware SPI CLK/D0 = GPIO14
Hardware SPI MOSI/D1 = GPIO13
RESET = GPIO16
DC = GPIO2
CS = GPIO15, pull-down 10k to GND

Code

Make sure to use the latest nodemcu firmware (greater than 0.9.6)

you can download from here

https://github.com/nodemcu/nodemcu-firmware/releases/download/0.9.6-dev_20150704/nodemcu_float_0.9.6-dev_20150704.bin

function init_spi_display()
     -- Hardware SPI CLK  = GPIO14
     -- Hardware SPI MOSI = GPIO13
     -- Hardware SPI MISO = GPIO12 (not used)
     -- CS, D/C, and RES can be assigned freely to available GPIOs
     local cs  = 8 -- GPIO15, pull-down 10k to GND
     local dc  = 4 -- GPIO2
     local res = 0 -- GPIO16
     spi.setup(1, spi.MASTER, spi.CPOL_LOW, spi.CPHA_LOW, spi.DATABITS_8, 0)
     disp = u8g.ssd1306_128x64_spi(cs, dc, res)
end
function prepare()
     disp:setFont(u8g.font_6x10)
     disp:setFontRefHeightExtendedText()
     disp:setDefaultForegroundColor()
     disp:setFontPosTop()
end

function stringtest(a)
     disp:drawStr(30+a, 31, " 0")
     disp:drawStr90(30, 31+a, " 90")
     disp:drawStr180(30-a, 31, " 180")
     disp:drawStr270(30, 31-a, " 270")
end
function line(a)
     disp:drawStr(0, 0, "drawLine")
     disp:drawLine(7+a, 10, 40, 55)
     disp:drawLine(7+a*2, 10, 60, 55)
     disp:drawLine(7+a*3, 10, 80, 55)
     disp:drawLine(7+a*4, 10, 100, 55)
end
function triangle(a)
     local offset = a
     disp:drawStr(0, 0, "drawTriangle")
     disp:drawTriangle(14,7, 45,30, 10,40)
     disp:drawTriangle(14+offset,7-offset, 45+offset,30-offset, 57+offset,10-offset)
     disp:drawTriangle(57+offset*2,10, 45+offset*2,30, 86+offset*2,53)
     disp:drawTriangle(10+offset,40+offset, 45+offset,30+offset, 86+offset,53+offset)
end

function ascii_1()
     local x, y, s
     disp:drawStr(0, 0, "ASCII page 1")
     for y = 0, 5, 1 do
          for x = 0, 15, 1 do
               s = y*16 + x + 32
               disp:drawStr(x*7, y*10+10, string.char(s))
          end
     end
end

function extra_page(a)
     disp:drawStr(0, 12, "setScale2x2")
     disp:setScale2x2()
     disp:drawStr(0, 6+a, "setScale2x2")
     disp:undoScale()
end

function draw(draw_state)
     local component = bit.rshift(draw_state, 3)

     prepare()

     if (component == 0) then
         stringtest(bit.band(draw_state, 7))
     elseif (component == 1) then
          line(bit.band(draw_state, 7))
     elseif (component == 2) then
          triangle(bit.band(draw_state, 7))
     elseif (component == 3) then
          ascii_1()
     elseif (component == 4) then
            extra_page(bit.band(draw_state, 7))
     end
end

function graphics_test(delay)
     print("--- Starting Graphics Test ---")
     local draw_state
     for draw_state = 0, 4 + 8*8, 1 do
          disp:firstPage()
          repeat
               draw(draw_state)
          until disp:nextPage() == false
          --print(node.heap())
          tmr.delay(delay)
          -- re-trigger Watchdog!
          tmr.wdclr()
     end
     print("--- Graphics Test done ---")
end

--init_i2c_display()
init_spi_display()
graphics_test(50000)

function init_spi_display()

-- Hardware SPI CLK = GPIO14

-- Hardware SPI MOSI = GPIO13

-- Hardware SPI MISO = GPIO12 (not used)

-- CS, D/C, and RES can be assigned freely to available GPIOs

local cs = 8 -- GPIO15, pull-down 10k to GND

local dc = 4 -- GPIO2

local res = 0 -- GPIO16

spi.setup(1, spi.MASTER, spi.CPOL_LOW, spi.CPHA_LOW, spi.DATABITS_8, 0)

disp = u8g.ssd1306_128x64_spi(cs, dc, res)

end

function prepare()

disp:setFont(u8g.font_6x10)

disp:setFontRefHeightExtendedText()

disp:setDefaultForegroundColor()

disp:setFontPosTop()

end

function stringtest(a)

disp:drawStr(30+a, 31, " 0")

disp:drawStr90(30, 31+a, " 90")

disp:drawStr180(30-a, 31, " 180")

disp:drawStr270(30, 31-a, " 270")

end

function line(a)

disp:drawStr(0, 0, "drawLine")

disp:drawLine(7+a, 10, 40, 55)

disp:drawLine(7+a*2, 10, 60, 55)

disp:drawLine(7+a*3, 10, 80, 55)

disp:drawLine(7+a*4, 10, 100, 55)

end

function triangle(a)

local offset = a

disp:drawStr(0, 0, "drawTriangle")

disp:drawTriangle(14,7, 45,30, 10,40)

disp:drawTriangle(14+offset,7-offset, 45+offset,30-offset, 57+offset,10-offset)

disp:drawTriangle(57+offset*2,10, 45+offset*2,30, 86+offset*2,53)

disp:drawTriangle(10+offset,40+offset, 45+offset,30+offset, 86+offset,53+offset)

end

function ascii_1()

local x, y, s

disp:drawStr(0, 0, "ASCII page 1")

for y = 0, 5, 1 do

for x = 0, 15, 1 do

s = y*16 + x + 32

disp:drawStr(x*7, y*10+10, string.char(s))

end

function extra_page(a)

disp:drawStr(0, 12, "setScale2x2")

disp:setScale2x2()

disp:drawStr(0, 6+a, "setScale2x2")

disp:undoScale()

end

function draw(draw_state)

local component = bit.rshift(draw_state, 3)

prepare()

if (component == 0) then

stringtest(bit.band(draw_state, 7))

elseif (component == 1) then

line(bit.band(draw_state, 7))

elseif (component == 2) then

triangle(bit.band(draw_state, 7))

elseif (component == 3) then

ascii_1()

elseif (component == 4) then

extra_page(bit.band(draw_state, 7))

end

function graphics_test(delay)

print("--- Starting Graphics Test ---")

local draw_state

for draw_state = 0, 4 + 8*8, 1 do

disp:firstPage()

repeat

draw(draw_state)

until disp:nextPage() == false

--print(node.heap())

tmr.delay(delay)

-- re-trigger Watchdog!

tmr.wdclr()

end

print("--- Graphics Test done ---")

end

--init_i2c_display()

init_spi_display()

graphics_test(50000)

Example 2

myStr0 = "Hello"
myStr1 = "Hello"
myStr2 = "Hello" -- place holders for the other lines
myStr3 = "Hello" -- place holders for the other lines
myStr4 = "Hello"
myStr5 = "Hello"
myStr6 = "Hello"
myStr7 = "Hello"

-- setup SPI and connect display
function init_spi_display()
     -- Hardware SPI CLK  = GPIO14   5
     -- Hardware SPI MOSI = GPIO13   7
     -- Hardware SPI MISO = GPIO12 (not used)
     -- CS, D/C, and RES can be assigned freely to available GPIOs
     local cs  = 8 -- GPIO15, pull-down 10k to GND
     local dc  = 4 -- GPIO2
     local res = 0 -- GPIO16
     spi.setup(1, spi.MASTER, spi.CPOL_LOW, spi.CPHA_LOW, spi.DATABITS_8, 0)
     disp = u8g.ssd1306_128x64_spi(cs, dc, res)
end

-- graphic test components
function prepare()
     disp:setFont(u8g.font_6x10)
     disp:setFontRefHeightExtendedText()
     disp:setDefaultForegroundColor()
     disp:setFontPosTop()
end


function draw(void) 
    prepare()
    disp:drawStr(0,0,myStr0)
    disp:drawStr(0,8,myStr1)
    disp:drawStr(0,16,myStr2)
    disp:drawStr(0,24,myStr3)
    disp:drawStr(0,32,myStr4)
    disp:drawStr(0,40,myStr5)
    disp:drawStr(0,48,myStr6)
    disp:drawStr(0,56,myStr7)
end


function loop(void) 
-- this is the loop that u8g apparently needs for display
  disp:firstPage() 
  repeat
    draw()
  until disp:nextPage() == false
 end

 

 
-- below is to set up the timer to keep hitting the display
init_spi_display()

tmr.alarm(3,1000,1,function()   
   disp:firstPage() 
   repeat
      draw()
   until disp:nextPage() == false 
end)

myStr0 = "Hello"

myStr1 = "Hello"

myStr2 = "Hello" -- place holders for the other lines

myStr3 = "Hello" -- place holders for the other lines

myStr4 = "Hello"

myStr5 = "Hello"

myStr6 = "Hello"

myStr7 = "Hello"

-- setup SPI and connect display

function init_spi_display()

-- Hardware SPI CLK = GPIO14 5

-- Hardware SPI MOSI = GPIO13 7

-- Hardware SPI MISO = GPIO12 (not used)

-- CS, D/C, and RES can be assigned freely to available GPIOs

local cs = 8 -- GPIO15, pull-down 10k to GND

local dc = 4 -- GPIO2

local res = 0 -- GPIO16

spi.setup(1, spi.MASTER, spi.CPOL_LOW, spi.CPHA_LOW, spi.DATABITS_8, 0)

disp = u8g.ssd1306_128x64_spi(cs, dc, res)

end

-- graphic test components

function prepare()

disp:setFont(u8g.font_6x10)

disp:setFontRefHeightExtendedText()

disp:setDefaultForegroundColor()

disp:setFontPosTop()

end

function draw(void)

prepare()

disp:drawStr(0,0,myStr0)

disp:drawStr(0,8,myStr1)

disp:drawStr(0,16,myStr2)

disp:drawStr(0,24,myStr3)

disp:drawStr(0,32,myStr4)

disp:drawStr(0,40,myStr5)

disp:drawStr(0,48,myStr6)

disp:drawStr(0,56,myStr7)

end

function loop(void)

-- this is the loop that u8g apparently needs for display

disp:firstPage()

repeat

draw()

until disp:nextPage() == false

end

-- below is to set up the timer to keep hitting the display

init_spi_display()

tmr.alarm(3,1000,1,function()

disp:firstPage()

repeat

draw()

until disp:nextPage() == false

end)

Example 3

function init_spi_display()
     local cs  = 8 -- GPIO15, pull-down 10k to GND
     local dc  = 4 -- GPIO2
     local res = 0 -- GPIO16
     spi.setup(1, spi.MASTER, spi.CPOL_LOW, spi.CPHA_LOW, spi.DATABITS_8, 0)
     disp = u8g.ssd1306_128x64_spi(cs, dc, res)
end


function draw()
   disp:setFont(u8g.font_6x10)
   disp:drawStr( 30, 10, "Hello IoT!")
   disp:drawStr( 20, 50, "www.htlinux.com")
   disp:drawLine(0, 25, 128, 25);
   disp:setFont(u8g.font_chikita)
   disp:drawStr( 20, 40, "Hello welcome users") 
   
end
  
function display()
  disp:firstPage()
  repeat
       draw()
  until disp:nextPage() == false      
  display();
end

init_spi_display()

display()

function init_spi_display()

local cs = 8 -- GPIO15, pull-down 10k to GND

local dc = 4 -- GPIO2

local res = 0 -- GPIO16

spi.setup(1, spi.MASTER, spi.CPOL_LOW, spi.CPHA_LOW, spi.DATABITS_8, 0)

disp = u8g.ssd1306_128x64_spi(cs, dc, res)

end

function draw()

disp:setFont(u8g.font_6x10)

disp:drawStr( 30, 10, "Hello IoT!")

disp:drawStr( 20, 50, "www.htlinux.com")

disp:drawLine(0, 25, 128, 25);

disp:setFont(u8g.font_chikita)

disp:drawStr( 20, 40, "Hello welcome users")

end

function display()

disp:firstPage()

repeat

draw()

until disp:nextPage() == false

display();

end

init_spi_display()

display()

Have a happy coding!!

Tags: 0.96" oled esp8266 esp8266 oled nodemcu nodemcu display nodemcu oled oled oled code SSD1306

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