Re: Example - measure temperature using 1-wire DS1820
Posted: Tue Dec 09, 2014 8:10 am
I'll try to simulate negative temperatures and I'll update the example tonight.
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pin = 9
ow.setup(pin)
counter=0
lasttemp=-999
function bxor(a,b)
local r = 0
for i = 0, 31 do
if ( a % 2 + b % 2 == 1 ) then
r = r + 2^i
end
a = a / 2
b = b / 2
end
return r
end
function getTemp()
addr = ow.reset_search(pin)
repeat
tmr.wdclr()
if (addr ~= nil) then
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
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)
data = nil
data = string.char(ow.read(pin))
for i = 1, 8 do
data = data .. string.char(ow.read(pin))
end
crc = ow.crc8(string.sub(data,1,8))
if (crc == data:byte(9)) then
t = (data:byte(1) + data:byte(2) * 256)
if (t > 32768) then
t = (bxor(t, 0xffff)) + 1
t = (-1) * t
end
t = t * 625
lasttemp = t
print("Last temp: " .. lasttemp)
end
tmr.wdclr()
end
end
end
addr = ow.search(pin)
until(addr == nil)
end
srv=net.createServer(net.TCP)
srv:listen(8080,function(conn)
getTemp()
t1 = lasttemp / 10000
t2 = (lasttemp >= 0 and lasttemp % 10000) or (10000 - lasttemp % 10000)
conn:send("Temperature: " .. t1 .. "." .. string.format("%04d", t2) .. "\n\n")
conn:on("sent",function(conn) conn:close() end)
end)
nc esp 8080
Temperature: -9.1875
function getTemp()
tmr.wdclr()
ow.reset(pin)
ow.skip(pin)
ow.write(pin,0x44,1)
tmr.delay(800000)
ow.reset(pin)
ow.skip(pin)
ow.write(pin,0xBE,1)
data = nil
data = string.char(ow.read(pin))
data = data .. string.char(ow.read(pin))
t = (data:byte(1) + data:byte(2) * 256)
if (t > 32768) then
t = (bxor(t, 0xffff)) + 1
t = (-1) * t
end
t = t * 625
lasttemp = t
print("Last temp: " .. lasttemp)
end