134 lines
3.3 KiB
Lua
134 lines
3.3 KiB
Lua
--------------------------------------------------------------------------------
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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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-- Vowstar <vowstar@nodemcu.com>
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--------------------------------------------------------------------------------
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-- Set module name as parameter of require
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local modname = ...
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local M = {}
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_G[modname] = M
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--------------------------------------------------------------------------------
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-- Local used variables
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--------------------------------------------------------------------------------
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-- DS18B20 dq pin
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local pin = nil
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-- DS18B20 default pin
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local defaultPin = 9
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--------------------------------------------------------------------------------
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-- Local used modules
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--------------------------------------------------------------------------------
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-- Table module
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local table = table
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-- String module
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local string = string
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-- One wire module
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local ow = ow
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-- Timer module
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local tmr = tmr
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-- Limited to local environment
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setfenv(1,M)
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--------------------------------------------------------------------------------
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-- Implementation
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--------------------------------------------------------------------------------
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C = 0
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F = 1
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K = 2
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function setup(dq)
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pin = dq
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if(pin == nil) then
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pin = defaultPin
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end
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ow.setup(pin)
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end
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function addrs()
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setup(pin)
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tbl = {}
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ow.reset_search(pin)
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repeat
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addr = ow.search(pin)
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if(addr ~= nil) then
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table.insert(tbl, addr)
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end
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tmr.wdclr()
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until (addr == nil)
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ow.reset_search(pin)
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return tbl
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end
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function readNumber(addr, unit)
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result = nil
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setup(pin)
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flag = false
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if(addr == nil) then
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ow.reset_search(pin)
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count = 0
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repeat
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count = count + 1
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addr = ow.search(pin)
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tmr.wdclr()
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until((addr ~= nil) or (count > 100))
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ow.reset_search(pin)
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end
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if(addr == nil) then
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return result
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end
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crc = ow.crc8(string.sub(addr,1,7))
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if (crc == addr:byte(8)) then
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if ((addr:byte(1) == 0x10) or (addr:byte(1) == 0x28)) then
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-- print("Device is a DS18S20 family device.")
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ow.reset(pin)
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ow.select(pin, addr)
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ow.write(pin, 0x44, 1)
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-- tmr.delay(1000000)
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present = ow.reset(pin)
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ow.select(pin, addr)
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ow.write(pin,0xBE,1)
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-- print("P="..present)
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data = nil
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data = string.char(ow.read(pin))
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for i = 1, 8 do
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data = data .. string.char(ow.read(pin))
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end
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-- print(data:byte(1,9))
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crc = ow.crc8(string.sub(data,1,8))
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-- print("CRC="..crc)
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if (crc == data:byte(9)) then
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if(unit == nil or unit == C) then
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t = (data:byte(1) + data:byte(2) * 256) * 625
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elseif(unit == F) then
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t = (data:byte(1) + data:byte(2) * 256) * 1125 + 320000
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elseif(unit == K) then
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t = (data:byte(1) + data:byte(2) * 256) * 625 + 2731500
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else
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return nil
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end
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t = t / 10000
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-- print("Temperature="..t1.."."..t2.." Centigrade")
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-- result = t1.."."..t2
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return t
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end
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tmr.wdclr()
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else
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-- print("Device family is not recognized.")
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end
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else
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-- print("CRC is not valid!")
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end
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return result
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end
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function read(addr, unit)
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t = readNumber(addr, unit)
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if (t == nil) then
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return nil
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else
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return t
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end
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end
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-- Return module table
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return M
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