Tag Archives: Temperature Sensor

Using Arduino code on Spark Core

In an earlier post Spark Core Weather Station I presented code that was reading weather sensors and sent the data over USB to a PC terminal. However the approach I took there to combine all code into a single file is not very practical. So now that the Spark IDE supports multiple project files we can just include Arduino library files.

Screenshot 2014-04-16 20.49.13

So here are some hints how to get Arduino library code and sketches to compile in the Spark framework. I use a TMP102 I2C temperature sensor to demonstrate the porting. Below is an example Sketch that reads the temperature values and sends them to the serial interface:

The main reason this code fails to compile is the Arduino Wire.h library include statement fails on the cloud based Spark Core IDE. The TMP102 sketch code use I2C. So it includes the Arduino Wire Library with the following line:

This triggers an error in the Spark IDE. To solve this problem I created a new library named Wire.h with the following content:

With this library all we have to do is to uncomment or delete the original include statement. By adding Wire.h file the IDE automatically adds a line like this to the source code:

As long as the Arduino source follows basic guidelines for portable code I did not face much difficulties to use existing Arduino sources on the Spark Core.

Spark Core Weather Station

In my previous blog post I described my first encounter with the Spark Core. Today I want to demonstrate a first simple code example. For this I connected the Spark Core to a Weather Shield from Sparkfun. The shield offers sensors for light, humidity, temperature and pressure. It can even be extended with rain and wind sensors as well as GPS.
.Spark Core Weather
The shield comes with a nice set of libraries and examples that I used as a starting point. To keep things really simple, I combine the entire Weather Shield source with the sensor library functions and the setup() and loop() into a single file. This did not take long and compiled quickly. I also removed the wind and rain related functionality as I did not plan to use those. The source code below takes measurements every second and writes the them to the USB serial port.

For debugging I used the Serial Communication link over USB. Windows users have to install a COM driver. However, MAC and Linux support the Spark Core USB functionality out of the box.

I was really pleased to see how well the Spark Core supports Arduino libraries and well written legacy code. With only a few code modifications I had the sensors up and running.

The setup is now streaming values over a USB cable to a PC. There I captured the values with Tera Term and created a Weather Graph from the comma separated values (CVS). The example below shows the pressure curve of a Bay Area Storm passing by at end of February 2014.
CA Storm
This setup is a somewhat trivial example that a basic Arduino can also do. The project really does not take advantage of the Spak Core's connectivity to the internet. So stay tuned for my next blog post where I will add internet connectivity to the setup.