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+--------------------------------------------------------------------------------
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+-- DS18B20 one wire module for NODEMCU
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+-- NODEMCU TEAM
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+-- LICENCE: http://opensource.org/licenses/MIT
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+-- @voborsky, @devsaurus, TerryE 26 Mar 2017
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+--------------------------------------------------------------------------------
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+local modname = ...
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+
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+-- Used modules and functions
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+local type, tostring, pcall, ipairs =
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+ type, tostring, pcall, ipairs
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+-- Local functions
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+local ow_setup, ow_search, ow_select, ow_read, ow_read_bytes, ow_write, ow_crc8,
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+ ow_reset, ow_reset_search, ow_skip, ow_depower =
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+ ow.setup, ow.search, ow.select, ow.read, ow.read_bytes, ow.write, ow.crc8,
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+ ow.reset, ow.reset_search, ow.skip, ow.depower
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+
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+local node_task_post, node_task_LOW_PRIORITY = node.task.post, node.task.LOW_PRIORITY
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+local string_char, string_dump = string.char, string.dump
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+local now, tmr_create, tmr_ALARM_SINGLE = tmr.now, tmr.create, tmr.ALARM_SINGLE
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+local table_sort, table_concat = table.sort, table.concat
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+local file_open = file.open
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+local conversion
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+
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+local DS18B20FAMILY = 0x28
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+local DS1920FAMILY = 0x10 -- and DS18S20 series
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+local CONVERT_T = 0x44
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+local READ_SCRATCHPAD = 0xBE
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+local READ_POWERSUPPLY= 0xB4
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+local MODE = 1
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+
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+local pin, cb, unit = 3
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+local status = {}
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+
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+local debugPrint = function() return end
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+
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+--------------------------------------------------------------------------------
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+-- Implementation
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+--------------------------------------------------------------------------------
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+local function enable_debug()
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+ debugPrint = function (...) print(now(),' ', ...) end
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+end
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+
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+local function to_string(addr, esc)
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+ if type(addr) == 'string' and #addr == 8 then
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+ return ( esc == true and
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+ '"\\%u\\%u\\%u\\%u\\%u\\%u\\%u\\%u"' or
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+ '%02X:%02X:%02X:%02X:%02X:%02X:%02X:%02X '):format(addr:byte(1,8))
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+ else
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+ return tostring(addr)
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+ end
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+end
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+
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+local function readout(self)
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+ local next = false
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+ local sens = self.sens
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+ local temp = self.temp
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+ for i, s in ipairs(sens) do
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+ if status[i] == 1 then
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+ ow_reset(pin)
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+ local addr = s:sub(1,8)
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+ ow_select(pin, addr) -- select the sensor
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+ ow_write(pin, READ_SCRATCHPAD, MODE)
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+ local data = ow_read_bytes(pin, 9)
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+
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+ local t=(data:byte(1)+data:byte(2)*256)
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+ -- t is actually signed so process the sign bit and adjust for fractional bits
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+ -- the DS18B20 family has 4 fractional bits and the DS18S20s, 1 fractional bit
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+ t = ((t <= 32767) and t or t - 65536) *
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+ ((addr:byte(1) == DS18B20FAMILY) and 625 or 5000)
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+ local crc, b9 = ow_crc8(string.sub(data,1,8)), data:byte(9)
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+
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+ if unit == 'F' then
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+ t = (t * 18)/10 + 320000
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+ elseif unit == 'K' then
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+ t = t + 2731500
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+ end
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+ local sgn = t<0 and -1 or 1
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+ local tA = sgn*t
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+ local tH=tA/10000
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+ local tL=(tA%10000)/1000 + ((tA%1000)/100 >= 5 and 1 or 0)
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+
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+ if tH and (t~=850000) then
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+ debugPrint(to_string(addr),(sgn<0 and "-" or "")..tH.."."..tL, crc, b9)
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+ if crc==b9 then temp[addr]=t end
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+ status[i] = 2
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+ end
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+ end
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+ next = next or status[i] == 0
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+ end
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+ if next then
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+ node_task_post(node_task_LOW_PRIORITY, function() return conversion(self) end)
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+ else
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+ --sens = {}
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+ if cb then
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+ node_task_post(node_task_LOW_PRIORITY, function() return cb(temp) end)
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+ end
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+ end
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+end
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+
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+conversion = (function (self)
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+ local sens = self.sens
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+ local powered_only = true
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+ for _, s in ipairs(sens) do powered_only = powered_only and s:byte(9) ~= 1 end
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+ if powered_only then
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+ debugPrint("starting conversion: all sensors")
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+ ow_reset(pin)
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+ ow_skip(pin) -- skip ROM selection, talk to all sensors
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+ ow_write(pin, CONVERT_T, MODE) -- and start conversion
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+ for i, _ in ipairs(sens) do status[i] = 1 end
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+ else
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+ local started = false
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+ for i, s in ipairs(sens) do
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+ if status[i] == 0 then
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+ local addr, parasite = s:sub(1,8), s:byte(9) == 1
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+ if parasite and started then break end -- do not start concurrent conversion of powered and parasite
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+ debugPrint("starting conversion:", to_string(addr), parasite and "parasite" or "")
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+ ow_reset(pin)
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+ ow_select(pin, addr) -- select the sensor
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+ ow_write(pin, CONVERT_T, MODE) -- and start conversion
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+ status[i] = 1
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+ if parasite then break end -- parasite sensor blocks bus during conversion
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+ started = true
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+ end
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+ end
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+ end
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+ tmr_create():alarm(750, tmr_ALARM_SINGLE, function() return readout(self) end)
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+end)
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+
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+local function _search(self, lcb, lpin, search, save)
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+ self.temp = {}
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+ if search then self.sens = {}; status = {} end
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+ local sens = self.sens
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+ pin = lpin or pin
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+
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+ local addr
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+ if not search and #sens == 0 then
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+ -- load addreses if available
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+ debugPrint ("geting addreses from flash")
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+ local s,check,a = pcall(dofile, "ds18b20_save.lc")
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+ if s and check == "ds18b20" then
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+ for i = 1, #a do sens[i] = a[i] end
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+ end
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+ debugPrint (#sens, "addreses found")
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+ end
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+
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+ ow_setup(pin)
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+ if search or #sens == 0 then
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+ ow_reset_search(pin)
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+ -- ow_target_search(pin,0x28)
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+ -- search the first device
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+ addr = ow_search(pin)
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+ else
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+ for i, _ in ipairs(sens) do status[i] = 0 end
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+ end
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+ local function cycle()
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+ if addr then
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+ local crc=ow_crc8(addr:sub(1,7))
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+ if (crc==addr:byte(8)) and ((addr:byte(1)==DS1920FAMILY) or (addr:byte(1)==DS18B20FAMILY)) then
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+ ow_reset(pin)
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+ ow_select(pin, addr)
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+ ow_write(pin, READ_POWERSUPPLY, MODE)
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+ local parasite = (ow_read(pin)==0 and 1 or 0)
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+ sens[#sens+1]= addr..string_char(parasite)
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+ status[#sens] = 0
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+ debugPrint("contact: ", to_string(addr), parasite == 1 and "parasite" or "")
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+ end
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+ addr = ow_search(pin)
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+ node_task_post(node_task_LOW_PRIORITY, cycle)
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+ else
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+ ow_depower(pin)
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+ -- place powered sensors first
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+ table_sort(sens, function(a, b) return a:byte(9)<b:byte(9) end) -- parasite
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+ -- save sensor addreses
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+ if save then
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+ debugPrint ("saving addreses to flash")
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+
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+ local addr_list = {}
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+ for i =1, #sens do
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+ local s = sens[i]
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+ addr_list[i] = to_string(s:sub(1,8), true)..('.."\\%u"'):format(s:byte(9))
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+ end
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+ local save_statement = 'return "ds18b20", {' .. table_concat(addr_list, ',') .. '}'
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+ debugPrint (save_statement)
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+ local save_file = file_open("ds18b20_save.lc","w")
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+ save_file:write(string_dump(loadstring(save_statement)))
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+ save_file:close()
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+ end
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+ -- end save sensor addreses
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+ if lcb then node_task_post(node_task_LOW_PRIORITY, lcb) end
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+ end
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+ end
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+ cycle()
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+end
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+
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+local function read_temp(self, lcb, lpin, lunit, force_search, save_search)
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+ cb, unit = lcb, lunit or unit
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+ _search(self, function() return conversion(self) end, lpin, force_search, save_search)
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+end
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+
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+ -- Set module name as parameter of require and return module table
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+local M = {
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+ sens = {},
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+ temp = {},
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+ C = 'C', F = 'F', K = 'K',
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+ read_temp = read_temp, enable_debug = enable_debug
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+}
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+_G[modname or 'ds18b20'] = M
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+return M
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