Data Logger using Raspberry Pi Scott Cairns 1817523

1.3Achievements

• 
  Learning to use Raspbian Wheezy operating system
  
• 
  Understanding how to connect to the Raspberry Pi remotely (using SSH)
  
• 
  Developing an understanding of Python programming language
  
• 
  Understanding of the required packages to get the webcam to stream as well as the command line parameters for these packages
  
• 
  Understanding of the required packages and Python modules to interact with GPIO and the Gertboard to obtain reading from sensors and control output
  
• 
  Understanding of the EEML package to allow real time graphing via COSM
  
• 
  Understanding of threading and multiprocessing in Python to allow logging of three different sensors as well as keyboard inputs
  
• 
  Learning how to use a breadboard, Gertboard and the electrical components used with this (such as LEDs, buttons, sensors, capacitors, resistors)
  
• 
  Developed a functioning data logger
  

The overall achievement from this project is a Raspberry Pi with the suitable software and hardware to allow it to record data from sensors; this includes two items of software one which runs the Python script to allow data logging and one to assist in the installation of the software with the installation guide.

1.4Overview of Dissertation

The thesis contains five different chapters which explain the project, discuss how it was developed, what was required, the testing of the product and how it could be extended

Chapter 1 gives an introduction to the project, background and what this project has done, the goals and scope of the project and the achievements of the project. Chapter 2 contains a review of projects in the same area and how they differ from this project, including a brief description of some of the hardware used by this and similar projects. Chapter 3 provides a description of the software and hardware used to achieve the goal of creating a Data logger using the Raspberry Pi, including what each software package is used for, as well as the design of the project. Chapter 4 includes the testing of this software and product as well as detailed issues and limitations faced during this project. Chapter 5 gives the conclusion and discusses potential future work for the project.

2State-of-The-Art

Although the Raspberry Pi is a relatively new device (officially released 29 February 2012) it has generated a massive amount of interest due to the low cost of the device, this has resulted in a massive amount of projects being undertaken on the Raspberry Pi in the short time it has been available.

2.1Hardware

To the best knowledge of the author, no project of this exact specification has been developed. Data loggers using the Raspberry Pi appear to be common however little appear to be based on visual and audio information, using GPIO inputs and outputs as well as allowing portability. The GPIO (General Purpose Input / Output) is a collection of pins which can be accessed on the Raspberry Pi to allow use with other electrical components such as LEDs, buttons, and sensors. The project also makes use of the Gertboard Rev 2 which has only recently been released (officially released 17 Jan 2013)¹¹ to interact with and extend the GPIO capabilities, the Gertboard connects directly to the Raspberry Pi GPIO pins by slotting on to the pins, it contains several LEDs, switches, converters, and a motor controller, one of these converters is the MCP3002 analogue to digital converter which is built into the board. The fully assembled Gertboard is shown in Figure 1 (image taken from ModMyPi³²)


A fully assembled Gertboard with the Pi
It appears most projects involving GPIO sensors appear to make use of the MCP3008 and MCP3002 standalone analogue to digital converters rather than the Gertboard. The MCP3002 is a 2.7V Dual channel 10 bit analogue to digital converter with SPI serial interface¹⁶, the MCP3008 is a 2.7V 8 channel 10 bit analogue to digital converter with SPI serial interface¹⁷, and both of these devices are standalone chips which can be put into the breadboard. A recent development from RS Components UK is the camera board, they aim to produce a camera board which is capable of 5 megapixels and can record 1080p H.264 videos at 30 frames per second. The Adafruit Pi Cobbler is a breakout kit for the Raspberry Pi; it allows the user to make use of a ribbon-type cable to connect the GPIO pins to the custom PCB which can then be used on a solderless breadboard allowing easy connection to specific gpio pins. The Adafruit Pi Cobbler is shown in Figure 2 (image taken from eBay³³)



The Adafruit Pi Cobbler
The Pi-Face digital interface is also another breakout board similar to the Gertboard. This device slots on to the GPIO pins and allows the functionality of the GPIO to be extended to perform actions such as motor control, light control, and sense inputs. The Pi-Face interface is shown in Figure 3 (image taken from Pi-Face³⁴)



The Pi-Face Digital Interface

2.2Commercial data loggers

Commercial data loggers typically focus on monitoring one sensor and tend to be very expensive; an example of a low cost temperature recorder is the MadgeTech Temp101A³¹. This data logger includes storage for up to 1 million temperature readings and the ability to start and stop the recording. This data logger costs nearly £60 while only using one sensor. An example of a wireless data logger using temperature sensor and external sensors is the TandD RTR-574-H. This device includes two sensors which record optical and temperature readings as well as the ability to extend on this with two external sensors as well as allowing wireless connections. This data logger costs almost £380.

Directory: ~aka

Download 200.65 Kb.

Share with your friends: