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-- DS18B20 one wire module for NODEMCU
-- by @voborsky, @devsaurus
-- encoder module is needed only for debug output; lines can be removed if no
-- debug output is needed and/or encoder module is missing
--
-- by default the module is for integer version, comment integer version and
-- uncomment float version part for float version
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return({
pin=3,
sens={},
temp={},
conversion = function(self)
local pin = self.pin
for i,s in ipairs(self.sens) do
if s.status == 0 then
print("starting conversion:", encoder.toHex(s.addr), 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, function() self:readout() end)
end,
readTemp = function(self, cb, lpin)
if lpin then self.pin = lpin end
local pin = self.pin
self.cb = cb
self.temp={}
ow.setup(pin)
self.sens={}
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
-- 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)
table.insert(self.sens,{addr=addr, parasite=parasite, status=0})
print("contact: ", encoder.toHex(addr), parasite == 1 and "parasite" or " ")
end
addr = ow.search(pin)
tmr.wdclr()
end
-- place powered sensors first
table.sort(self.sens, function(a,b) return a.parasite<b.parasite end)
node.task.post(node.task.MEDIUM_PRIORITY, function() self:conversion() end)
end,
readout=function(self)
local pin = self.pin
local next = false
if not self.sens then return 0 end
for i,s in ipairs(self.sens) do
-- print(encoder.toHex(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
if 1/2 == 0 then
-- 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
self.temp[s.addr]=(sgn<0 and "-" or "")..tH.."."..tL
print(encoder.toHex(s.addr),(sgn<0 and "-" or "")..tH.."."..tL)
s.status = 2
end
-- end integer version
else
-- float version
if t and (math.floor(t/10000)~=85) then
self.temp[s.addr]=t/10000
print(encoder.toHex(s.addr), t)
s.status = 2
end
-- end float version
end
end
next = next or s.status == 0
end
if next then
node.task.post(node.task.MEDIUM_PRIORITY, function() self:conversion() end)
else
self.sens = nil
if self.cb then
node.task.post(node.task.MEDIUM_PRIORITY, function() self.cb(self.temp) end)
end
end
end
})
