The raspberry Pi board is a cheap and a very versatile tool. It runs a variant Linux operating system which means that it comes with a huge variety of software packages. Also it means that it provides a familiar environment to the software people. It comes with an extension connector that allows adding different peripheral boards such as relays or sensor adapters. Also because it has an Ethernet connector (or a wireless adapter connected to the USB port), it means that the board can be controlled remotely and it can be used as a web server.

Hardware

Here is an easy way to read and control the temperature. Raspberry Pi Temperature Controller comes with a connector to a K type thermocouple. A thermocouple is basically a junction between 2 different metals that outputs a very small voltage which is proportional to the temperature. The voltage is very small at the level of microvolts.

The voltage has to be amplified and then digitized by an analog to digital converter and sent to the Raspberry Pi through an I2C interface. Also there are 2 relays that are meant to control heating and cooling but they can be assigned to a more general purpose. The relays could control fans, peltier coolers, and larger relays.

Software

Let’s talk a bit about software. There are a great variety of languages that can be used like C, C++, shell script, Python, Perl, PHP, Java, C# (Mono), Ruby and many others. The great thing about Linux is that it already supports the access to GPIO pins and also I2C port.

Here is a shell script example how a port can be set to high (or 3.3 volts):
[sourcecode language=”shell”]
echo 1 > /sys/class/gpio/gpio17/value

or low ( 0 volts)

echo 0 > /sys/class/gpio/gpio17/value
[/sourcecode]
This can be done directly from command line.

The board comes with some example code and scripts. Since all the control is done in software it means that different control algorithms can be added to suit a specific project. Also the board can be used just as a temperature data logger, and the data can be saved in a file.

Also the board comes with some example code to display the temperature on a webpage.

The web interface is written in Python and a framework called Flask which provides a minimal and a very efficient way to create web content.

Some of the scripts:

• read_temperature – will print the temperature read from the sensor
• relay_on cold/hot – will turn on the relays named cold or hot
• relay_off cold/hot – will turn off relays names cold or hot
• temperature_hold – will try to control the temperature by turning the cold or hot relays

Manufacturing

So far the company created two prototypes and makes some preparations for a more extended production.

To speed up the production, Robogaia Industries, LLC just purchased a pick-and-place machine. A pick-and-place machine is a device that puts the electronic parts on the board (usually much faster and more precise than a human operator). In the past they soldered the boards by hand, but after a few hundred of boards the job becomes tedious and boring.