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-- DS18B20 one wire module for NODEMCU
-- NODEMCU TEAM
-- LICENCE: http://opensource.org/licenses/MIT
-- Vowstar <vowstar@nodemcu.com>
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-- Set module name as parameter of require
local modname = ...
local M = {}
_G[modname] = M
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-- Local used variables
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-- DS18B20 dq pin
local pin = nil
-- DS18B20 default pin
local defaultPin = 9
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-- Local used modules
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-- Table module
local table = table
-- String module
local string = string
-- One wire module
local ow = ow
-- Timer module
local tmr = tmr
-- Limited to local environment
setfenv(1,M)
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-- Implementation
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C = 0
F = 1
K = 2
function setup(dq) 
    pin = dq
	if(pin == nil) then
		pin = defaultPin		
	end
	ow.setup(pin)
end

function addrs()
	setup(pin)
	tbl = {}
	ow.reset_search(pin)
	repeat
		addr = ow.search(pin)
		if(addr ~= nil) then
			table.insert(tbl, addr)	
		end
		tmr.wdclr()
	until (addr == nil)
	ow.reset_search(pin)
	return tbl
end

function readNumber(addr, unit)
  result = nil
  setup(pin)
  flag = false
  if(addr == nil) then
    ow.reset_search(pin)
	count = 0
    repeat
		count = count + 1
		addr = ow.search(pin)
		tmr.wdclr()
	until((addr ~= nil) or (count > 100))
	ow.reset_search(pin)
  end	
  if(addr == nil) then
	return result
  end
  crc = ow.crc8(string.sub(addr,1,7))
  if (crc == addr:byte(8)) then
    if ((addr:byte(1) == 0x10) or (addr:byte(1) == 0x28)) then
        -- print("Device is a DS18S20 family device.")
        ow.reset(pin)
        ow.select(pin, addr)
        ow.write(pin, 0x44, 1)
        -- tmr.delay(1000000)
        present = ow.reset(pin)
        ow.select(pin, addr)
        ow.write(pin,0xBE,1)
        -- print("P="..present)  
        data = nil
        data = string.char(ow.read(pin))
        for i = 1, 8 do
            data = data .. string.char(ow.read(pin))
        end
        -- print(data:byte(1,9))
        crc = ow.crc8(string.sub(data,1,8))
        -- print("CRC="..crc)
        if (crc == data:byte(9)) then
			if(unit == nil or unit == C) then
				t = (data:byte(1) + data:byte(2) * 256) * 625
			elseif(unit == F) then
				t = (data:byte(1) + data:byte(2) * 256) * 1125 + 320000 
			elseif(unit == K) then
				t = (data:byte(1) + data:byte(2) * 256) * 625 + 2731500
			else
				return nil
			end            
            t1 = t / 10000
            t2 = t % 10000
            -- print("Temperature="..t1.."."..t2.." Centigrade")
			-- result = t1.."."..t2
			return t1, t2
        end                   
        tmr.wdclr()
    else
     -- print("Device family is not recognized.")
    end
  else
   -- print("CRC is not valid!")
  end
  return result
end

function read(addr, unit)
	t1, t2 = readNumber(addr, unit)
	if((t1 == nil ) or (t2 ==nil)) then
		return nil
	else	
		return t1.."."..t2
	end
end

-- Return module table
return M