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-- DS18B20 one wire module for NODEMCU
-- NODEMCU TEAM
-- LICENCE: http://opensource.org/licenses/MIT
-- @voborsky, @devsaurus, TerryE 26 Mar 2017
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local modname = ...
-- Used modules and functions
local table, string, ow, tmr, print, type, tostring, pcall, ipairs =
table, string, ow, tmr, print, type, tostring, pcall, ipairs
-- Local functions
local ow_setup, ow_search, ow_select, ow_read, ow_read_bytes, ow_write, ow_crc8, ow_reset, ow_reset_search, ow_skip, ow_depower =
ow.setup, ow.search, ow.select, ow.read, ow.read_bytes, ow.write, ow.crc8, ow.reset, ow.reset_search, ow.skip, ow.depower
local node_task_post, node_task_LOW_PRIORITY = node.task.post, node.task.LOW_PRIORITY
local string_char, string_dump = string.char, string.dump
local now, tmr_create, tmr_ALARM_SINGLE = tmr.now, tmr.create, tmr.ALARM_SINGLE
local table_sort, table_concat = table.sort, table.concat
local math_floor = math.floor
local file_open = file.open
table, string, tmr, ow = nil, nil, nil, nil
local DS18B20FAMILY = 0x28
local DS1920FAMILY = 0x10 -- and DS18S20 series
local CONVERT_T = 0x44
local READ_SCRATCHPAD = 0xBE
local READ_POWERSUPPLY= 0xB4
local MODE = 1
local pin, cb, unit = 3
local status = {}
local debugPrint = function() return end
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-- Implementation
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local function enable_debug()
debugPrint = function (...) print(now(),' ', ...) end
end
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(self)
local next = false
local sens = self.sens
local temp = self.temp
for i, s in ipairs(sens) do
if status[i] == 1 then
ow_reset(pin)
local addr = s:sub(1,8)
ow_select(pin, addr) -- select the sensor
ow_write(pin, READ_SCRATCHPAD, MODE)
data = ow_read_bytes(pin, 9)
local t=(data:byte(1)+data:byte(2)*256)
-- t is actually signed so process the sign bit and adjust for fractional bits
-- the DS18B20 family has 4 fractional bits and the DS18S20s, 1 fractional bit
t = ((t <= 32767) and t or t - 65536) *
((addr:byte(1) == DS18B20FAMILY) and 625 or 5000)
if 1/2 == 0 then
-- integer version
if unit == 'F' then
t = (t * 18)/10 + 320000
elseif unit == 'K' then
t = t + 2731500
end
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 (t~=850000) then
temp[addr]=(sgn<0 and "-" or "")..tH.."."..tL
debugPrint(to_string(addr),(sgn<0 and "-" or "")..tH.."."..tL)
status[i] = 2
end
-- end integer version
else
-- float version
if t and (math_floor(t/10000)~=85) then
t = t / 10000
if unit == 'F' then
t = t * 18/10 + 32
elseif unit == 'K' then
t = t + 27315/100
end
self.temp[addr]=t
debugPrint(to_string(addr), t)
status[i] = 2
end
-- end float version
end
end
next = next or status[i] == 0
end
if next then
node_task_post(node_task_LOW_PRIORITY, function() return conversion(self) end)
else
--sens = {}
if cb then
node_task_post(node_task_LOW_PRIORITY, function() return cb(temp) end)
end
end
end
local function conversion(self)
local sens = self.sens
local powered_only = true
for _, s in ipairs(sens) do powered_only = powered_only and s:byte(9) ~= 1 end
if powered_only then
debugPrint("starting conversion: all sensors")
ow_reset(pin)
ow_skip(pin) -- select the sensor
ow_write(pin, CONVERT_T, MODE) -- and start conversion
for i, s in ipairs(sens) do status[i] = 1 end
else
for i, s in ipairs(sens) do
if status[i] == 0 then
local addr, parasite = s:sub(1,8), s:byte(9)
debugPrint("starting conversion:", to_string(addr), parasite == 1 and "parasite" or " ")
ow_reset(pin)
ow_select(pin, addr) -- select the sensor
ow_write(pin, CONVERT_T, MODE) -- and start conversion
status[i] = 1
if parasite == 1 then break end -- parasite sensor blocks bus during conversion
end
end
end
tmr_create():alarm(750, tmr_ALARM_SINGLE, function() return readout(self) end)
end
local function _search(self, lcb, lpin, search, save)
self.temp = {}
if search then self.sens = {}; status = {} end
local temp = self.temp
local sens = self.sens
pin = lpin or pin
local addr
if not search and #sens == 0 then
-- load addreses if available
debugPrint ("geting addreses from flash")
local s,check,a = pcall(dofile, "ds18b20_save.lc")
if s and check == "ds18b20" then
for i = 1, #a do sens[i] = a[i] end
end
debugPrint (#sens, "addreses found")
end
ow_setup(pin)
if search or #sens == 0 then
ow_reset_search(pin)
-- ow_target_search(pin,0x28)
-- search the first device
addr = ow_search(pin)
else
for i, s in ipairs(sens) do status[i] = 0 end
end
local function cycle()
debugPrint("cycle")
if addr then
local crc=ow_crc8(addr:sub(1,7))
if (crc==addr:byte(8)) and ((addr:byte(1)==DS1920FAMILY) or (addr:byte(1)==DS18B20FAMILY)) then
ow_reset(pin)
ow_select(pin, addr)
ow_write(pin, READ_POWERSUPPLY, MODE)
local parasite = (ow_read(pin)==0 and 1 or 0)
sens[#sens+1]= addr..string_char(parasite) -- {addr=addr, parasite=parasite, status=0}
debugPrint("contact: ", to_string(addr), parasite == 1 and "parasite" or " ")
end
addr = ow_search(pin)
node_task_post(node_task_LOW_PRIORITY, cycle)
else
ow_depower(pin)
-- place powered sensors first
table_sort(sens, function(a, b) return a:byte(9)<b:byte(9) end) -- parasite
-- save sensor addreses
if save then
debugPrint ("saving addreses to flash")
local addr_list = {}
for i =1, #sens do
local s = sens[i]
addr_list[i] = to_string(s:sub(1,8), true)..('.."\\%u"'):format(s:byte(9))
end
local save_statement = 'return "ds18b20", {' .. table_concat(addr_list, ',') .. '}'
debugPrint (save_statement)
local save_file = file_open("ds18b20_save.lc","w")
save_file:write(string_dump(loadstring(save_statement)))
save_file:close()
end
-- end save sensor addreses
if lcb then node_task_post(node_task_LOW_PRIORITY, lcb) end
end
end
cycle()
end
local function read_temp(self, lcb, lpin, lunit, force_search, save_search)
cb, unit = lcb, lunit or unit
_search(self, function() return conversion(self) end, lpin, force_search, save_search)
end
-- Set module name as parameter of require and return module table
local M = {
sens = {},
temp = {},
C = 'C', F = 'F', K = 'K',
read_temp = read_temp, enable_debug = enable_debug
}
_G[modname or 'ds18b20'] = M
return M