From 02e150314ad7d47b9c36cfce20d857e73bd3f08c Mon Sep 17 00:00:00 2001
From: Nathaniel Wesley Filardo <nwf@cs.jhu.edu>
Date: Sun, 22 Jan 2017 19:59:18 -0500
Subject: [PATCH] Fork dvv-nodemcu-things lcd1602

Improve initialization sequence, remove buggy 'run' method.
This file and all changes to it retain the original (MIT) license,
independent of the rest of this project.
---
 _external/lcd1602.lua | 110 ++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 110 insertions(+)
 create mode 100644 _external/lcd1602.lua

diff --git a/_external/lcd1602.lua b/_external/lcd1602.lua
new file mode 100644
index 0000000..5c846cb
--- /dev/null
+++ b/_external/lcd1602.lua
@@ -0,0 +1,110 @@
+------------------------------------------------------------------------------
+-- LCD 1602 module
+--
+-- LICENSE: http://opensource.org/licenses/MIT
+-- Vladimir Dronnikov <dronnikov@gmail.com>
+-- Compiled from various sources inc.
+--   http://www.avrfreaks.net/forum/lcd-display-iic-1602-atmega328p
+--   http://www.avrfreaks.net/sites/default/files/lcd_22.h
+--   https://github.com/nekromant/esp8266-frankenstein/blob/4880a04452ab745b1d99c0aedbb69cc2ba7fd5cb/include/driver/i2c_hd44780.h
+--
+-- Originally from
+-- https://github.com/dvv/nodemcu-thingies/blob/master/lcd1602.lua .
+-- Modified by nwf to improve comm reliability and remove buggy 'run'
+-- function.  This file retains its original license, as above, and is
+-- not subject to the license of the containing project.
+--
+-- Example:
+-- i2c.setup(0, 3, 4, i2c.SLOW)
+-- lcd = dofile("lcd1602.lua")()
+-- lcd:put(lcd:locate(0, 5), "Hello, dvv!")
+-- lcd:clear()
+-- lcd:define_char(0, { 10, 0, 14, 17, 17, 17, 14, 0 }) -- custom char o umlaut
+-- lcd:put(lcd:locate(0, 0), "\000!"); lcd:put(lcd:locate(0, 14), "!\000")
+------------------------------------------------------------------------------
+
+local _offsets = { [0] = 0x80, 0xC0, 0x94, 0xD4 } -- 20x4
+-- local _offsets = { [0] = 0x80, 0xC0, 0x90, 0xD0 } -- 16x4
+
+-- write byte helper
+local w = function(self, b, mode)
+  i2c.start(0)
+  i2c.address(0, self._adr, i2c.TRANSMITTER)
+  local bh = bit.band(b, 0xF0) + self._ctl + mode
+  local bl = bit.lshift(bit.band(b, 0x0F), 4) + self._ctl + mode
+  i2c.write(0, bh + 4, bh, bl + 4, bl)
+  i2c.stop(0)
+  tmr.delay(40)
+end
+
+-- backlight on/off
+local light = function(self, on)
+  self._ctl = on and 0x08 or 0x00
+  w(self, 0x00, 0)
+end
+
+-- clear screen
+local clear = function(self)
+  w(self, 0x01, 0)
+end
+
+-- return command to set cursor at row/col
+local locate = function(self, row, col)
+  return col + _offsets[row]
+end
+
+-- define custom char 0-7
+-- NB: e.g. use "\003" in argument to .put to display custom char 3
+local define_char = function(self, index, bytes)
+  w(self, 0x40 + 8 * bit.band(index, 0x07), 0)
+  for i = 1, #bytes do w(self, bytes[i], 1) end
+end
+
+-- write to lcd
+local put = function(self, ...)
+  for _, x in ipairs({...}) do
+    -- number?
+    if type(x) == "number" then
+      -- direct command
+      w(self, x, 0)
+    -- string?
+    elseif type(x) == "string" then
+      -- treat as data
+      for i = 1, #x do w(self, x:byte(i), 1) end
+    end
+  end
+end
+
+-- start lcd
+local init = function(self)
+  w(self, 0x33, 0) -- move to 8 bit data mode
+  w(self, 0x32, 0) -- move to 4 bit data mode
+  w(self, 0x28, 0) -- 2 lines, 5x8 dots
+  w(self, 0x0C, 0) -- display on, cursor and cursor blink off
+  w(self, 0x06, 0) -- position increment, no display shift
+  w(self, 0x02, 0) -- cursor home
+  w(self, 0x01, 0) -- clear display
+end
+
+-- instance metatable
+local meta = {
+  __index = {
+    clear = clear,
+    define_char = define_char,
+    init = init,
+    light = light,
+    locate = locate,
+    put = put,
+    run = run,
+  },
+}
+
+-- create new LCD1602 instance
+return function(adr)
+  local self = setmetatable({
+    _adr = adr or 0x27,
+    _ctl = 0x08,
+  }, meta)
+  self:init()
+  return self
+end
-- 
2.50.1