+ Add One-Wire example ds18b20.lua

examples/ds18b20.lua

@@ -0,0 +1,56 @@
+--[[
+-- 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