I recently purchased a particle photon IoT; a tiny reprogrammable IoT development board with inbuilt WiFi. It is available here to buy: https://store.particle.io/
There is a really good guide to getting it setup here, so I will only cover my thoughts on setting it up and using it as a wireless thermometer:
The setup is fairly straight forward, the device hosts a wireless network, using the particle smart phone application you can connect to it and provide your Wifi details. It will then connect to your home WiFi network.
I had to re-flash it and install Tinker (though this is as easy as pressing a button in the smartphone app), you can now view all of the I/O pins and read and write to them. This is a really nice feature and theres also great documentation on it here: https://docs.particle.io/guide/getting-started/tinker/core/
I wired up 3.3V output, ground and analog pins to a thermometer (TMP36) module. Using the a app, I got an analog reading from the A0 pin and calculated the temperature as follows:
Voltage at pin in milliVolts = ( (reading from pin) * (volts) ) / (max pin reading)
(904 * 3.3) / 4096 = 0.7283203125
I then converted it to Celsius using the following (-0.5 offset is to allow for negative temperatures). Have a look at https://learn.adafruit.com/tmp36-temperature-sensor/using-a-temp-sensor for more details.
(Voltage at pin in milliVolts – 0.5 (offset)) * 100 = 22.83 °C
(Which was about right for the room).
Overall, the Particle Photon was really easy to setup the smart phone application is very nice to use, the easy reading and writing of pins makes this a very useful development and prototype board.