Reading

Miles from Nowhere by Barbara Savage

ESP8266 net display

Using the previous lcdprint function here is a simple remote display. To display on it from your server you can use wget (or nc or whatever) eg.

a message
wget "http://xxx.xxx.xxx.xxx/?message=This%20is%20line%201&line=1&col=0" 
the time and date
wget "http://xxx.xxx.xxx.xxx/?message=`date +"%H:%M %a %d %b"`&line=2&col=0"
 

Here is the code based on the toggle_pin.lua webap (here)  Run node.compile() on this as well as the lcdprint or it runs out of heap.

--based on the webap toggle_pin.lua
srv=net.createServer(net.TCP)
srv:listen(80,function(conn)
 conn:on("receive", function(client,request)
   local buf = "ok";
   local _, _, method, path, vars = string.find(request, "([A-Z]+) (.+)?(.+) HTTP");
   if(method == nil)then
      _, _, method, path = string.find(request, "([A-Z]+) (.+) HTTP");
   end
   local _GET = {}
   if (vars ~= nil)then
     for k, v in string.gmatch(vars, "(%w+)=([%(%)%-:%w%s%%]+)&*") do
        _GET[k] = v
      end
   end
 if (_GET.message ~= nil)then
  -- from http://lua-users.org/wiki/StringRecipes
  local function url_decode(str)
    str = string.gsub (str, "+", " ")
    str = string.gsub (str, "%%(%x%x)",function(h) return string.char(tonumber(h,16)) end)
    str = string.gsub (str, "\r\n", "\n")
    return str
  end 

  local line=1
  local col=0

  if (_GET.line~= nil) then  line=_GET.line+0 end
  if (_GET.col ~= nil) then  col=_GET.col+0 end
  local message=url_decode(_GET.message)
  dofile("lcdprint.lc").lcdprint(message,line,col)

 end
 client:send(buf);
 client:close();
 collectgarbage();
 end)
end) 

ESP8266 I2C LCD

Starting with the init and send code from from abel's post on ESP8266.com , thanks it was very helpful. Changed the lcdprint function to use bit-wise ops and  added cursor movement . The display I have is this  from banggood, the reg value needed to be 0x00 instead of 0x4e.

Example usage:

--print on the first line 
dofile("lcdprint.lua").lcdprint("This is line 1",1,0)
 --print on the second line 
dofile("lcdprint.lua").lcdprint("This is line 2",2,2)
--clear screen
dofile("lcdprint.lua").cls()
--home
dofile("lcdprint.lua").home()
--show cursor
dofile("lcdprint.lua").cursor(1)
--hide cursor
dofile("lcdprint.lua").cursor(0)  

Here is the code (to be saved in "lcdprint.lua")  

--based on http://www.esp8266.com/viewtopic.php?f=6&t=841&p=20082&hilit=lcd#p11075 by abel 

--   PCF8574
--   P7   P6   P5   P4    P3      P2   P1   P0
--   D7   D6   D5   D4   (BL)   EN   RW   RS
--   HD44780
local M
do
local id = 0
local sda = 4      -- GPIO2
local scl = 5      -- GPIO14
local dev = 0x27   -- PCF8574
local reg = 0x00   -- write
i2c.setup(id, sda, scl, i2c.SLOW)

local bl = 0x08      -- 0x08 = back light on

local function send(data)
   local value = {}
   for i = 1, #data do
      table.insert(value, data[i] + bl + 0x04 + rs)
      table.insert(value, data[i] + bl +  rs)      -- fall edge to write
   end
  
   i2c.start(id)
   i2c.address(id, dev ,i2c.TRANSMITTER)
   i2c.write(id, reg, value)
   i2c.stop(id)
end
 
if (rs == nil) then
-- init
 rs = 0
 send({0x30})
 tmr.delay(4100)
 send({0x30})
 tmr.delay(100)
 send({0x30})
 send({0x20, 0x20, 0x80})   -- 4 bit, 2 line
 send({0x00, 0x10})            -- display clear
 send({0x00, 0xc0})            -- display on
end

local function cursor(op)
 local oldrs=rs
 rs=0
 if (op == 1) then 
   send({0x00, 0xe0})            -- cursor on
  else 
   send({0x00, 0xc0})            -- cursor off
 end
 rs=oldrs
end

local function cls()
 local oldrs=rs
 rs=0
 send({0x00, 0x10})
 rs=oldrs
end

local function home()
 local oldrs=rs
 rs =0
 send({0x00, 0x20})
 rs=oldrs
end

local function lcdprint (str,line,col)
rs = 0
--move cursor
if (line == 2) then
 send({0xc0,bit.lshift(col,4)})
elseif (line==1) then 
 send({0x80,bit.lshift(col,4)})
end

rs = 1
for i = 1, #str do
 local char = string.byte(string.sub(str, i, i))
 send ({ bit.clear(char,0,1,2,3),bit.lshift(bit.clear(char,4,5,6,7),4)})
end

end

M={
lcdprint=lcdprint,
cls = cls,
home=home,
cursor=cursor,
}
end
return M



Reading

The Long Earth
The Long War
The Long Mars by  Terry Pratchett and Stephen Baxter