Step 1: Overview

I built a WiFi IoT board called WiThumb and would like to show you one of the many applications enabled by WiThumb. It is currently listed on KickStarter to make it available to more people. Check it out.

In short, WiThumb is an Arduino compatible WiFi IoT board with integrated high precision temperature sensor and 6-axis IMU (gyroscope + accelerometer). An optional plastic case could be ordered through KickStarter as well.

Specifications

32-bit MCU with 802.11b/g/n WiFi (ESP8266)
Integrated TCP/IP protocol stack
4MB Flash memory
Precision temperature sensor (+/- 0.25C typical accuracy)
6-axis Gyroscope + Accelerometer
IO pins: One 10-bit ADC, I2C and GPIOs
Breadboard friendly (0.1" pitch header holes)
Optional plastic case

Benefits

Compact (1.9 inch x 0.85 inch PCB)
USB Powered. Plug in anywhere.
Large community (Arduino, ESP8266 WiFi)
Easy to program
Easy to carry
Low cost
Low power (deep sleep mode)
Plastic case protects the electronics
Expandable

Step 2: Flash the WiThumb

(If you are familiar with ESP8266, you may skip step 2 and 3)

WiThumb is compatible with Arduino. However, it needs to be flashed before the first use. Here is how:

Download and install the NodeMCU flasher program here : https://github.com/nodemcu/nodemcu-flasher
Plug in WiThumb to your PC
Run NodeMCU flasher
Select the COM port that corresponds to WiThumb
Press the "Flash(F)" button in the program
Press the "flash" button on WiThumb for about 1 seconds and release it
It will take about 1 minute to complete the flash process.

Step 3: Install Arduino Core Libraries for ESP8266

In order to compile and load the executable to WiThumb through Arduino IDE, you need to add the core libraries for ESP8266 to Arduino environment. To do so, simply follow the instructions on this GitHub page.

Once it is done, invoke Arduino and select "NodeMCU 1.0" as your board. Now, you should be able to compile and load the executable to WiThumb.

Step 4: Download Temperature Sensor Library

The temperature sensor used in WiThumb is MCP9808 from Microchip.

There is a library written by Adafruit for MCP9808. Download it from here and add it to your Arduino IDE:

https://github.com/adafruit/Adafruit_MCP9808_Libra...

Step 5: Download My Code

The code could be downloaded from here:

https://github.com/ThomasCLee/funnyvale/tree/maste...

It should be pretty self-explanatory. It measures the temperature every 2 minutes (roughly).

Here are the steps:

initializes the temperature sensor and reads the temperature
logs into the WiFi network (you need to fill in the SSID and password in lines 28,29)
post the readings to the cloud (hosted on https://data.sparkfun.com). But before you can do that, you need to create a data stream and obtain a public key and a private key. Don't worry, I'll show you how in the next step.

Step 6: Upload Readings to the Cloud

To create a data stream, follow these steps

Go to https://data.sparkfun.com
Create a new data stream (by clicking 'create' button on the right)
Fill in all the mandatory entries. In the 'Fields' entry, enter 'temp'
Once you save it, a public key and a private key will be assigned. Private key is like the password. Don't share it with anyone else.
Now, enter both keys in lines 35 and 36 in the Arduino program
Once you saved, compiled and uploaded the program to WiThumb, it will start logging the temperature to Sparkfun every 2 minutes.
You may also open the Serial Monitor in Arduino to review the debug messages.
Once everything looks good, you could unplug WiThumb from your PC and plug it in to any USB type A connector to measure the temperature at any location interested.