nodemcu-firmware/examples/ds18b20-example.lua

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2014-12-08 09:23:12 +01:00
--'
-- 18b20 one wire example for NODEMCU
-- NODEMCU TEAM
-- LICENCE: http://opensource.org/licenses/MIT
-- Vowstar <vowstar@nodemcu.com>
--'
pin = 9
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