onewire-ds18b20.lua

--'
-- 18b20 one wire example for NODEMCU
-- NODEMCU TEAM
-- LICENCE: http://opensource.org/licenses/MIT
-- Vowstar <vowstar@nodemcu.com>
--' 

pin = 8
ow.setup(pin)
count = 0
repeat
  count = count + 1
  addr = ow.reset_search(pin)
  addr = ow.search(pin)
  tmr.wdclr()
until((addr ~= nil) or (count > 100))
if (addr == nil) then
  print("No more addresses.")
else
  print(addr:byte(1,8))
  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.")
        repeat
          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
             t = (data:byte(1) + data:byte(2) * 256) * 625
             t1 = t / 10000
             t2 = t % 10000
             print("Temperature= "..t1.."."..t2.." Centigrade")
          end                   
          tmr.wdclr()
        until false
    else
      print("Device family is not recognized.")
    end
  else
    print("CRC is not valid!")
  end
end

--     -- read temperature with DS18B20
-- --     node.compile("ds18b20.lua")   --  run this only once to compile and save to "ds18b20.lc"
--     t=require("ds18b20")
--     t.setup(9)
--     addrs=t.addrs()
--     -- Total DS18B20 numbers, assume it is 2
--     print(table.getn(addrs))
--     -- The first DS18B20
--     print(t.read(addrs[1],t.C))
--     print(t.read(addrs[1],t.F))
--     print(t.read(addrs[1],t.K))
--     -- The second DS18B20
--     print(t.read(addrs[2],t.C))
--     print(t.read(addrs[2],t.F))
--     print(t.read(addrs[2],t.K))
--     -- Just read
--     print(t.read())
--     -- Just read as centigrade
--     print(t.read(nil,t.C))
--     -- Don't forget to release it after use
--     t = nil
--     ds18b20 = nil
--     package.loaded["ds18b20"]=nil