diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
new file mode 100644
index 00000000..42be531f
--- /dev/null
+++ b/CONTRIBUTING.md
@@ -0,0 +1,7 @@
+## Contributing
+
+Thank you everyone for contributing to this project.
+
+Pull requests for new features and major fixes should be opened against the `dev` branch.
+
+*Note that the `pre_build` bin in the dev branch is never up-to-date.*
diff --git a/README.md b/README.md
index f4cf9c85..f3bd4973 100644
--- a/README.md
+++ b/README.md
@@ -92,7 +92,7 @@ build pre_build bin.
     <td>6</td><td>GPIO12</td><td></td><td></td>
   </tr>
   <tr>
-    <td>7</td><td>GPIO13</td<td></td><td></td>
+    <td>7</td><td>GPIO13</td><td></td><td></td>
    </tr>
 </table>
 #### [*] D0(GPIO16) can only be used as gpio read/write. no interrupt supported. no pwm/i2c/ow supported.
diff --git a/lua_examples/telnet.lua b/lua_examples/telnet.lua
index 18645187..22610445 100644
--- a/lua_examples/telnet.lua
+++ b/lua_examples/telnet.lua
@@ -29,11 +29,11 @@ function startServer()
    print("===Now, logon and input LUA.====")
 end
 
-tmr.alarm(1000, 1, function() 
+tmr.alarm(1, 1000, 1, function() 
    if wifi.sta.getip()=="0.0.0.0" then
       print("Connect AP, Waiting...") 
    else
       startServer()
-      tmr.stop()
+      tmr.stop(1)
    end
 end)
diff --git a/lua_modules/dht22/dht22.lua b/lua_modules/dht22/dht22.lua
index b7b04092..a80a1bd6 100644
--- a/lua_modules/dht22/dht22.lua
+++ b/lua_modules/dht22/dht22.lua
@@ -62,17 +62,17 @@ function M.read(pin)
 
   --DHT data acquired, process.
   for i = 1, 16, 1 do
-    if (bitStream[i] > 4) then
+    if (bitStream[i] > 3) then
       humidity = humidity + 2 ^ (16 - i)
     end
   end
   for i = 1, 16, 1 do
-    if (bitStream[i + 16] > 4) then
+    if (bitStream[i + 16] > 3) then
       temperature = temperature + 2 ^ (16 - i)
     end
   end
   for i = 1, 8, 1 do
-    if (bitStream[i + 32] > 4) then
+    if (bitStream[i + 32] > 3) then
       checksum = checksum + 2 ^ (8 - i)
     end
   end