You need an ESP8266 with nodemcu firmware. For programming your ESP8266 you need either an Arduino or other USB-to-serial adapter.
I'm using ESPlorer to program the LUA scripts onto the ESP8266 memory.
Connect the ESP8266 with the DHT11.
Connect the Arduino to the ESP8266 for programming the device. The Arduino can be removed after programming the device and if you are using an external power supply or battery.
| ESP8266 PIN | device |
|---|---|
| GND | GND |
| GPIO2 | - |
| GPIO0 | DHT11 data (2nd from left) & 3.3V VCC w/ 10kΩ resistor |
| URXD | Arduino 0 (RX), for programming |
| UTXD | Arduino 1 (TX), for programming |
| CH_PD | 3.3V VCC |
| RST | - |
| VCC | 3.3V VCC |
See also at Adafruit: "Connecting to a DHTxx Sensor"
Fritzing Parts: DHT11, ESP8266
The script is an adaption from ok1cdj's DHT11 script for Thingspeak.
Configure your wifi SSID and password in init.lua, configure your OpenSenseMap box id and temperature & humidity sensor ids in dht11.lua.
Save both init.lua & dht11.lua on your device, then restart it.