ds18b20.lua

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-- DS18B20 one wire module for NODEMCU
-- by @voborsky, @devsaurus
--
-- by default the module is for integer version, comment integer version and
-- uncomment float version part for float version
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local modname = ...

local ow_setup, ow_search, ow_select, ow_read, ow_read_bytes, ow_write, ow_crc8, ow_reset, ow_reset_search = 
      ow.setup, ow.search, ow.select, ow.read, ow.read_bytes, ow.write, ow.crc8, ow.reset, ow.reset_search
local node_task_post = node.task.post
local node_task_LOW_PRIORITY = node.task.LOW_PRIORITY
--local tmr_now = tmr.now

local pin = 3
local sens = {}
local temp= {}
local cb

-- local function to_string(addr, esc)
  -- if type(addr) == 'string' and #addr == 8 then
    -- return ( esc == true and
             -- '"\\%u\\%u\\%u\\%u\\%u\\%u\\%u\\%u"' or
             -- '%02X:%02X:%02X:%02X:%02X:%02X:%02X:%02X '):format(addr:byte(1,8)) 
  -- else
    -- return tostring(addr)
  -- end
-- end

local function readout()
  local next = false
  if not sens then return 0 end
  for i,s in ipairs(sens) do
    -- print(encoder.toBase64(s.addr), s.status)
    if s.status == 1 then
      ow_reset(pin)
      ow_select(pin, s.addr)   -- select the  sensor
      ow_write(pin, 0xBE, 0) -- READ_SCRATCHPAD
      data = ow_read_bytes(pin, 9)

      local t=(data:byte(1)+data:byte(2)*256)
      if (t > 0x7fff) then t = t - 0x10000 end
      if (s.addr:byte(1) == 0x28) then
        t = t * 625  -- DS18B20, 4 fractional bits
      else
        t = t * 5000 -- DS18S20, 1 fractional bit
      end
      
      -- integer version
      local sgn = t<0 and -1 or 1
      local tA = sgn*t
      local tH=tA/10000
      local tL=(tA%10000)/1000 + ((tA%1000)/100 >= 5 and 1 or 0)
            
      if tH and (tH~=85) then
        temp[s.addr]=(sgn<0 and "-" or "")..tH.."."..tL
        --print(('%02X:%02X:%02X:%02X:%02X:%02X:%02X:%02X '):format(s.addr:byte(1,8)),(sgn<0 and "-" or "")..tH.."."..tL)
        s.status = 2
      end
      -- end integer version
      -- -- float version
      -- if t and (math.floor(t/10000)~=85) then
        -- self.temp[s.addr]=t
        -- print(encoder.toBase64(s.addr), t)
        -- s.status = 2
      -- end
      -- -- end float version
    end
    next = next or s.status == 0
  end
  if next then 
    node_task_post(node_task_LOW_PRIORITY, conversion)
  else
    --sens = {}
    while #sens ~= 0 do rawset(sens, #sens, nil) end
    
    if cb then
      node_task_post(node_task_LOW_PRIORITY, function() return cb(temp) end) 
    end
  end
end

local function conversion()
  for i,s in ipairs(sens) do
    if s.status == 0 then
      --print("starting conversion:", ('%02X:%02X:%02X:%02X:%02X:%02X:%02X:%02X '):format(s.addr:byte(1,8)), s.parasite == 1 and "parasite" or " ")
      ow_reset(pin)
      ow_select(pin, s.addr)  -- select the sensor
      ow_write(pin, 0x44, 1)  -- and start conversion
      s.status = 1
      if s.parasite == 1 then break end -- parasite sensor blocks bus during conversion
    end
  end
  tmr.create():alarm(750, tmr.ALARM_SINGLE, readout)
end

local function readTemp(lcb, lpin)
  --local start = tmr_now()
  cb = lcb
  --temp={}
  while #temp ~= 0 do rawset(temp, #temp, nil) end
  if lpin then pin = lpin end
  ow_setup(pin)
  
  --sens={}
  while #sens ~= 0 do rawset(sens, #sens, nil) end
  ow_reset_search(pin)
  -- ow_target_search(pin,0x28)
  -- search the first device
  local addr = ow_search(pin)
  -- and loop through all devices
  while addr do -- !!!!!!!!!!!!!!!!!!!!!!! should be looped in a task, also separated to separate
    -- search next device
    local crc=ow_crc8(string.sub(addr,1,7))
    if (crc==addr:byte(8)) and ((addr:byte(1)==0x10) or (addr:byte(1)==0x28)) then
      ow_reset(pin)
      ow_select(pin, addr)   -- select the found sensor
      ow_write(pin, 0xB4, 1) -- Read Power Supply [B4h]
      local parasite = (ow_read(pin)==0 and 1 or 0)
      sens[#sens+1]={addr=addr, parasite=parasite, status=0}
      --print("contact: ", ('%02X:%02X:%02X:%02X:%02X:%02X:%02X:%02X'):format(addr:byte(1,8)), parasite == 1 and "parasite" or " ")
    end
    addr = ow_search(pin)
    tmr.wdclr()
  --print(1,tmr_now()-start,#sens)
  end
    
  -- place powered sensors first
  table.sort(sens, function(a, b) return a.parasite<b.parasite end)

  node_task_post(node_task_LOW_PRIORITY, conversion)
  --print(2,tmr_now()-start)
end
 
local M = {
  sens=sens,
  temp=temp,
  readTemp = readTemp
}
_G[modname or 'ds18b20'] = M
return M