School of Technology Department of Computer Science Master Thesis Project 30p, Spring 2013 Wireless Farming: a mobile and Wireless Sensor Network based application to create farm field monitoring and plant protection for sustainable crop production and poverty reduction By Elias Edo Dube Supervisor: Bo Peterson Examiner: Carl Magnus Olsson
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School of Technology
Department of Computer Science
Master Thesis Project 30p, Spring 2013
Wireless Farming: a mobile and Wireless Sensor Network based application to create farm field
monitoring and plant protection for sustainable crop production and poverty reduction
The mobile application shall let a user access a sensor
data from the Wireless Farming system
The system shall check whether the user has a verified
user (or a register user)
If a user is not a verified or authorized user, the system
shall not allow the user access the sensor data
Data.Read
The system shall read sensor data over some interval
of time and log it to a cloud service provides by
xivity.com [24]
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Data.Value.Send
The system shall send the read sensor values to the
user
Data.Value.Save While sending read sensor values to a user the system
shall also save access history to a database
5.3 System architecture overview
Our proposed system is comprised of both hardware and software components (see
Figure 10: Overview of architecture of the proposed System) below. We make our design
decision using the design choices we obtain from our brainstorming session (see Figure 9:
Design process steps) and identified quality attributes (see Table 8: System quality attributes).
Therefore, we used open source hardware and software interfaces to design our proposed
system.
Figure 10: Overview of architecture of the proposed System
5.3.1 Hardware Interface
• Micro-controller: Arduino uno board – this microcontroller is based on
ATmega328 datasheet. It has 14 digital input/output pins, 6 analog inputs, a USB
connector, a power connector and built in clock speed resonator [51].
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Summary
Microcontroller ATmega328 Operating Voltage 5V Input Voltage (recommended) 7-12V Input Voltage (limits) 6-20V Digital I/O Pins 14 (of which 6 provide PWM output) Analog Input Pins 6 DC Current per I/O Pin 40 mA DC Current for 3.3V Pin 50 mA Flash Memory 32 KB (ATmega328) of which 0.5 KB used by bootloader SRAM 2 KB (ATmega328) EEPROM 1 KB (ATmega328) Clock Speed 16 MHz
• Ethernet shield: Arduino Ethernet shield – this Ethernet shield enables to
connect and Arduino to internet using a RJ45 cable [52].
Summary
• Requires an Arduino board • Operating voltage 5V (supplied from the Arduino Board) • Ethernet Controller: W5100 with internal 16K buffer • Connection speed: 10/100Mb • Connection with Arduino on SPI port • IEEE802.3af compliant • Low output ripple and noise (100mVpp) • Input voltage range 36V to 57V • Overload and short-circuit protection • 9V Output • High efficiency DC/DC converter: typ 75% @ 50% load • 1500V isolation (input to output)
In this section we present main functionalities of the proposed system. The proposed
system performs three main functionalities. The first and foremost activity of the
proposed system is to sense and collect environmental data. Then the next process is to
log the collected data to a cloud server. The final activity in the process is to make the
logged data available for visual access. Therefore, our design of the proposed system
corresponds to these identified processes of the system.
5.4.1 Designing the data sensing and collecting system
Figure 11: Sensing unit
The data sensing unit consists of sensor nodes which are placed in a farm field to
sense and monitor different environmental conditions (see Figure 11: Sensing unit
above). The sensors monitor farm field conditions like – soil, humidity, temperature and
Master Thesis project: Wireless Farming
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weather conditions and send sensed data to base station. The specific type of necessary
sensors for our proposed system are identified using the functional requirements (see 5.2
Design process) generated and literature reviews conducted on wireless sensor networks
(see 2.2 WSN and communication technologies ).
Data is generated within some interval of time that is set or when a user sends a
request to the system. In the first case of data generation, the sensor senses the
environment and sends the data to the web application. This occurs according to a
schedule that the system uses to put itself in active or sleep mode in order to save power
and lifetime. During the second case – when a user sends a request – the system collects
sensor data and sends it back to user’s mobile. This enables a farmer to send a request to
base station to check status of farm field. A base station processes the request received
and replies to request with sensor data read. This means, for instance, if a farmer sends a
request for soil moisture statues, a BS checks the sensor reading for the corresponding
request and replies with the collected data value.
Figure 12: Sensors
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5.4.2 Data logging unit design
The data logging unit is used to send the sensed data passed to the base station (see
Figure 13: Data logging unit below). Base stations are used to process and send sensor
readings to the internet.
Figure 13: Data logging unit architecture
Data sensed using the sensors is passed to the Arduino micro-processor. Arduino then
receives the sensor data and logs it to Xively cloud server using the Xively API [46][49].
Data is logged to the server on certain interval of time that is set. The Arduino micro-
processor that serves as a data logging unit is also responsible of executing sensor
readings. This makes it serve as base station of the system. For our prototype we
programmed data to be logged every second to simplify the process of evaluating the
system at later times.
Figure 14: Arduino Uno board and Arduino Ethernet Shield
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5.4.3 Data access system design
The next step we took in our design the proposed system is to decide the way of
making the sensor data available for the user. The sensor data uploaded to the internet
using the data logging unit can be accessed from both personal computers (PCs) and
mobile phones (see Figure 15: Data access unit architecture). We considered the presentation
of sensor reading to give meaning to the user. That is current sensor reading values
should be displayed along with a graphical visualization of sensor reading. The user will
be able to view also the physical location of a farm field and other details. The sensor
reading presentation is accessible in two ways. One option to access sensor reading is by
using the web. The other option is to access sensor reading using mobile phones.
Figure 15: Data access unit architecture
5.4.3.1 Accessing data using web visualizer
The sensor readings are continually uploaded to Xively [46][49] cloud service and
made available for access from any web browser using internet. We use Xively’s API
service to feed our sensor data to channels we created on their cloud service. It is possible
to view current sensor reading value both visually and numerically. The web application
provides a graphical presentation of sensor readings over some period of time – which
can range from current time up to three months of reading history. Using the web
application a user can view geographical location of a field a sensor is located.
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Figure 16: Accessing sensor data using the web app
5.4.3.2 Accessing data using mobile application
Mobile phones have become a part of our daily activities. With the rapid growth of
telecommunication technology in developing countries [17][18][47][48], the availability
of mobile phone services and their use among farmers is growing at the same time. Our
research aims how existing WSN technologies be used in conjunction with mobile
phones. It is also our researches objective to see ways how the combination of these two
technologies could be used to enable farmers monitor and control their farm field.
As part of one our interview question (see Appendix I: Interview Questions) we ask
farmers for a type phone they have. We used the answer of this interview question to
decide the platform on which we shall develop mobile based prototype.
The figure below (Figure 17) shows a screenshot of the main menu showing the menu
items and a sensor reading. The main menu items we included in our prototype are
humidity, soil temperature, soil moisture and farm temperature data streams.
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Figure 17: Wireless Farming system menu and a sample screenshot
In the figure below (Figure 18), shows a graphical view of a sensor reading of one
day. The value on the horizontal bar shows the sensor reading while the vertical bar
represents the time span. In addition to this sensor readings are shown on basis of an
hour, four days and over 30 days. The graphical representation of the sensor readings
makes it easy to visualize current status and sensor reading history over period of time.
Figure 18: A graphical view of sensor reading for one day
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6 Prototype Evaluation In this chapter we present the evaluation of our prototype. Our evaluation takes into
account only evaluating the mobile part of the proposed system. The purpose of
evaluating the proposed prototype is to present our solution to participants and get their
feedback. The participants whom we used to evaluate our prototypes are the farmers we
used for interview. Besides getting users feedback about usability of the proposed system,
evaluating our prototype helped check whether the system fulfils the function
requirements specified (see Table 9: Functional requirements).
6.1 Evaluation of Functional requirements
6.1.1 Data request and verification evaluation
• The mobile application shall let a user access a sensor data from the Wireless
Farming system
Accessing a sensor reading using the mobile phone application is possible.
The mobile phone application (Acosm) efficiently retrieves sensor data
reading uploaded to Xively. Users are prompted to try to use it. We
observed a users have slight level of difficulty to understand accessing the
application for the first time. After a while of trial all users we checked the
product with were comfortable using the application. At the end of every
user’s evaluation we ask for their opinion.
• The system shall check whether the user has a verified user (or a register user)
The mobile application verifies and authenticates when a user tries to use
the application. A user must provide the required credentials in order to
access the system. This makes every application to be accessed only by an
authorized user. This provides a specific application to be accessed only
by a specific user that the system is created for.
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• If a user is not a verified or authorized user, the system shall not allow the user
access the sensor data
The application does not allow a user access the system unless the user
provides correct authentication information. This is important to keep the
system secured and prevent an authorized access. Therefore, in order to
access sensor reading data a user should have a registered account.
6.1.2 Data read and send evaluation
• The system shall read sensor data over some interval of time and log it to a cloud
service provides by xively.com [24]
The Arduino based system we designed is capable of reading data on a
given interval of time and uploads it to Xively’s data stream. Sensor data
is uploaded to a specific data stream using API key and feed ID of the data
stream.
• The system shall send (or upload) the read sensor values to server
The proposed system frequently reads sensor values and uploads it to
cloud. This sensor readings can be accessed using the web or from a
mobile phone application. Data is uploaded within a given time interval
defined for the system.
6.1.3 Data saving evaluation
• While sending read sensor values to a user the system shall also save access
history to a database
At this version of the prototype the system saves sensor readings on
Xively cloud service. A user can access sensor reading records up to three
months. Since one plantation season for vegetable crop lasts for three
months, it could be enough data to monitor throughout the plantation
season. However, it is important for a farmer to keep farm field
information for longer time. It helps to make decision for consequent
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plantation seasons. In order to decide on what crop type to plant next, and
identify which season and soil is best for a certain crop type, it is
important for a farmer to get access of sensor data that have been saved for
long time.
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7 Discussion and Conclusion
7.1 Limitations
The proposed system’s mobile based prototype has been evaluated with farmers. This
was conducted in order to get feedback from future users of the system (see 5.1 Design
guideline and Figure 9: Design process steps) and confirm the requirements identified have
been met in the system (see Table 9: Functional requirements ). By doing so we have are
able to get insight for future work – both to improve the system and enhance the
usability. However, ensuring the usability and functionality of the mobile part of our
proposed system’s prototype was important, more test and evaluation needs to be carries
out on the hardware part of the proposed prototype as well. The functionality of the
designed hardware prototype have not been tested and evaluated under actual
environmental conditions out in the field. This might lead to a failure if the system is
implemented without testing the hardware components of the proposed system out in the
field. Furthermore, it is the mobile phone application part of the prototype that we
evaluated. We gave higher priority for the mobile part over the web part of our
application since the main aim of our research is to investigate how mobile phones and
WSNs are used to enable farmer in Ethiopia control and monitor their farm field. The
budgets allocated to conduct the field work in Ethiopia is also of limited amount to allow
us do everything.
7.2 Answering the Research Questions
In this section we provide how we answered our research questions.
RQ1: What are the common methods (or ways) used by farmers to monitor a farm
field?
To answer this research question, we conducted a field work in Ethiopia in which
we interviewing farmers, done field observation (see section 3.1: Case study and
section 4.2: Interview and interview analysis). Then we used the interview and
observation results to learn and understand common methods farmers employ to
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monitor and manage a farm. By identifying the common ways of farm field
monitoring used by farmers and learning the parameters a farmer use to monitor a
plant, we identify user requirements and check the need for quality attributes(see
5.1Design guideline).
RQ2: How can Wireless Sensor Networks in combination with mobile phone enable
farmers monitor a farm field?
For answering this research question we used the result we obtained from the
interview we conducted. We asked the participants in our interview (middle scale
irrigation based farmer in Meki,Oromia, Ethiopia) what type of mobile phones
they use ( see Appendix 1.Interview: Agricultural management and farm field
monitoring by farmers in Ethiopia). In addition to this, we did a literature review to
examine existing mobile application development environments that work with
WSN technologies (see section 2.1Use of WSN in agriculture and section 2.3: Mobile
phone use among farmers). We used the results to answer this research question by
designing a prototype (see chapter 5Design and prototype). Our prototype shows
the possibility of managing farm field and accessing services using mobile
phones.
The data we gathered show that most of the farmers use Samsung galaxy
S2 and Iphone 4 mobile phones. There are also few farmers who have Blackberry
mobile phones. The diverse type of mobile phone usage among farmers made it
challenging to identify a platform to develop our prototype on. However, after
comparing the functional requirements we identified and technical information we
obtained from our literature review on WSN, we decided to make an Android
based application.
We used the feedbacks we received from our prototype evaluation with
farmers in Ethiopia. After each time a user evaluates our prototype, we recorded
textually users experience and level of satisfaction to examine the usability and
usefulness of our proposed system. We also prompted users if they find such a
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system to be of use to assist them in their daily activities. The results we achieved
from our assessment show that farmers think such system to be of greater help to
carry out their daily farming activities. It is in this manner we approached to
answer this research question using the feedbacks we obtained from farmers
during our prototype evaluation (see section 6 Prototype Evaluation).
7.3 Contribution
In this thesis research we have studied similar products (and researches) that existing
out in the market (see section 2 Literature Review). This enabled us to get significant
inputs to conduct our research and identifies areas that need knowledge contribution as
well.
We found most projects on WSN in agriculture to be research oriented (see Table
1:Similar WSN projects). Our literature review and field work in Ethiopia indicate lack of
research on use of mobile phones and WSNs technologies to enable middle-scale-
irrigation-based-farmer in the country monitor and control their farm field. For this
reason, we conducted a research which investigates ways of using mobile phones in
conjunction with WSNs to enable farmers in Ethiopia monitor and control a farm field.
We used functional requirements we identified from a firsthand data we obtained from
our field work and extensive literature review we conducted to address the issues we
raised and answer our research questions (see section 1.3Project aim).
Furthermore, our research motivates the possibility of carry out an extensive research
in the area of WSN and mobile phone technologies; and the role this could play on
improvement of agricultural methods in the context of developing countries.
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7.4 Future work
The research presented in this thesis indicates some more areas to exist for future
research.
Firstly, a study of how to use alarming system in a Wireless Farming System (WFS)
can be investigated. Including an alarming system in WFS involves sending a warning or
alarm to a farmer’s phone when a certain condition occurs. For this, more research needs
to be conducted to identify the parameters and learn the conditions that are severe for
plants in context of DCs.
Secondly, we believe that such a system designed for farming use requires including a
Decision Support (DS) unit. Most of the farmers who participated in our interview
expressed they use their indigenous knowledge and own experience to make decision
while using fertilizers and pesticides. This exposes crops under treated or use of more
resource than require. In short, further study that investigates a cost effective and
scientifically helpful ways on how to associate sensor data reading with professional
explanation. One way to do this is to conduct a study of designing and Expert System
(ES) which supports decision making by associating sensor readings with professional
(scientific) information.
Finally, what we see as another potential of future work is integrating existing services
in WFS. For instance, a farmer can be enabled access weather forecasts from within the
same system. This creates the condition not to leave the application alone but makes
system suitable for the farmer to make a irrigation schedule while viewing other farm
field conditions. Commodity exchange information can be also included. Therefore, it is
relevant to study available existing services and APIs that could be of significant
importance for farming.
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7.5 Conclusion
In conclusion, with a user focused design approach, our research show that mobile
phones can be used as a tool to enable farmers in DCs monitor a farm field. We have
identified the main concerns farmers have regarding carry a diagnosis of different aspects
of their farm field and following up the status of a plantation. we relied on data we
obtained from our field work and literatures we reviewed to create a context to assess to
what extent WSNs be used to monitor farm field conditions and work with existing
mobile phone platforms. We identified user requirements common among middle scale
irrigation farmers in Developing countries taking the case in East Showa zone, Ethiopia.
We used inputs we got from our field work and literature review to formulate a design
guideline and make a design decision on how to create a prototype. In addition to
learning about requirements we have evaluated our prototype with users to validate its
functionalities meet their requirements. Furthermore, we have managed to answer our
research questions. And the result of the proposed Wireless Farming System (WFS)
shows the possibility of enabling farmers in DCs monitor their farm field using their
mobile phones.
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Appendix I: Interview Questions
1. Interview: Agricultural management and farm field monitoring by farmers in Ethiopia
The objective of conducting this interview is to gather a firsthand data from farmers in
Ethiopia to learn how farmers manage and monitor their farm field. We do this to identify
system design requirements. All the information you provide will be used for the master
thesis report only.
Name:
Where you Work:
1. What are your main daily activities?
2. What type of crops do you plant?
3. How big is your farm? How much investment does it require? How is the profit
margin?
4. What are the common risks of production loss?
5. Can you briefly explain how you keep track of your farm field during the day?
6. How do you access your farm field (both physically and remotely)?
7. How do you use your mobile phone in your farming business? What type of
mobile phone do you have? Can you please show me?
8. If a sensor based application is installed to enable you monitor your farm field
using your mobile phone and internet services, would you be willing to pay for
that?
Thank you for your time!
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Appendix II: use cases
Table 10: Use Case 1: Weather data
Use Case ID 1
Use Case Name Weather data
Created by Elias
Actors Users/farmers
Description This action allows a farmer to send a weather information request to the system and gets weather condition detail
Preconditions · The user must have a functional WSNFarming system. · The user must have the WSNFarming system app on his mobile
phone. · There should be a mobile network coverage both where the
WSNFarming system is installed and at the location of the user
Postconditions The user will get a weather information detail on his mobile phone.
Normal Flow · A user logs in to the app on his phone. · Selects weather information option from the menu. · If the user has mobile network and his number is register on the
system the app will send a request for sensor data to the system · The system then reads the sensor data and also checks other weather
stations information · The system sends the sensor data to the user’s mobile phone. · The system updates access history on the database.
Alternative Flows
1. Use the web based application.
Priority Medium
Frequency of Use
Depends on the user’s preference.
Table 11: Use Case 2: Soil Moisture data
Use Case ID 2
Use Case Name
Soil moisture data
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Created by Elias
Actors Users/farmers
Description This action allows a farmer to send a soil moisture information request to the system and condition of the soil moisture level and detailed explanation of the data reading.
Preconditions · The user must have a functional WSNFarming system. · The user must have the WSNFarming system app on his mobile
phone. · There should be a mobile network coverage both where the
WSNFarming system is installed and at the location of the user
Postconditions The user will get soil moisture level with a detailed explanation of the status on his mobile phone.
Normal Flow · A user logs in to the app on his phone. · Selects ‘soil moisture’ option from the menu. · If the user has mobile network and his number is register on the
system the app will send a request for sensor data to the system · The system then reads the soil moisture data from the sensors · The system sends the sensor data to the user’s mobile phone. · The system updates access history on the database.
Alternative Flows
1. Use the web based application.
Priority High
Frequency of Use
Depends on the user’s preference.
Table 12: Use Case 3: Soil Temperature data
Use Case ID 3
Use Case Name
Soil Temperature data
Created by Elias
Actors Users/farmers
Description This action allows a farmer to send a soil temperature status request to the system and gets back the status of the soil temperature with a
Master Thesis project: Wireless Farming
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detail that explains what it means to his crop
Preconditions · The user must have a functional WSNFarming system. · The user must have the WSNFarming system app on his mobile
phone. · There should be a mobile network coverage both where the
WSNFarming system is installed and at the location of the user
Postconditions The user will get soil temperature information with detailed explanation on his mobile phone.
Normal Flow · A user logs in to the app on his phone. · Selects ‘Soil Temperature’ option from the menu. · If the user has mobile network and his number is register on the
system the app will send a request for sensor data to the system · The system then reads the soil temperature data from the soil
temperature sensors · The system sends the sensor data to the user’s mobile phone. · The system updates access history on the database.
Alternative Flows
1. Use the web based application.
Priority High
Frequency of Use
Depends on the user’s preference.
Table 13: Use Case 4: Farm temperature data
Use Case ID 4
Use Case Name Farm temperature data
Created by Elias
Actors Users/farmers
Description This action allows a farmer to send a farm temperature request to the system and gets temperature of his farm field on the moment he is requesting the information
Preconditions · The user must have a functional WSNFarming system. · The user must have the WSNFarming system app on his mobile
phone. · There should be a mobile network coverage both where the
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WSNFarming system is installed and at the location of the user
Postconditions The user will get a farm field temperature detail on his mobile phone.
Normal Flow · A user logs in to the app on his phone. · Selects ‘Farm Temperature’ option from the menu. · If the user has mobile network and his number is register on the
system the app will send a request for sensor data to the system · The system then reads the sensor data from the temperature sensors
placed in the farm field · The system sends the farm temperature sensor data to the user’s
mobile phone. · The system updates access history on the database.
Alternative Flows
1. Use the web based application.
Priority Medium
Frequency of Use
Depends on the user’s preference.
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References [1] “Climate Change and Agriculture in Africa”. Available at:
http://www.ceepa.co.za/climate_change/index.html [Accessed October 15, 2012]
[2] “Fact Sheet: The world Bank and Agriculture in Africa.” Available at:
[34] J. E. Carroll and W. F. Wilcox. Effects of Humidity on the Development of
Grapevine Powdery Mildew. Phytopathology, 93(9):1137–1144, September 2003.
[35] W. Dargie and M. Zimmerling. Wireless sensor networks in the context of
developing countries. In IFIP World IT Forum (WITFOR), 2007.
[36] ECH2O Soil Moisture and Microclimate Monitoring. Documentation available at
http://www.ech2o.com/.
[37] S. Gadgil, P.R.S. Rao, and K.N. Rao. Use of climate information for farm-level decision making: rainfed groundnut in southern India. Agricultural Systems, 74, 2002.
[38] B. A. George, S. A. Shende, and N. S. Raghuwanshi. Development and testing of
an irrigation scheduling model. Agricultural Water Management, 46(2), 2000. [39] G.L. Hammer, N. Nicholls, and C. Mitchell, editors. Applications of seasonal
climate forecasting in agriculture and natural ecosystems: The Australian experience. Kluwer Academic Publishers, Dordrecht, The Netherlands, 2000.
[40] L. Horst. The dilemmas of water division: Considerations and criteria for
irrigation system design. Technical report, International Water Management Institute, 1998.
[41] J. Panchard. Computer-assisted Cognition: Using Wireless Sensor Networks to
Assist the Monitoring of Agricultural Fields. Technical report, EPFL, Lausanne, 2006. Available at http://people.epfl.ch/jacques.panchard.
[42] J. Panchard. Survey onWireless Sensor Networks for Agriculture. Technical report, EPFL, Lausanne, 2007.
[43] N. Ramanathan, L. Balzano, D. Estrin, M. Hansen, T. Harmon, J. Jay, W. Kaiser,
and G. Sukhatme. Designing wireless sensor networks as a shared resource for sustainable development. In International Conference on Information and Communication Technologies and Development, 2006.
[44] Profile of East Shoa Zone, Livestock and Irrigation Value-chains for Ethiopian
Smallholders (LIVES), July 2012. [45] BEDRU BESHIR, Small Scale Irrigation Users Peasant Horticulture in Dugda
Bora And Adami Tulu Jido Kombolcha Woredas East Shewa Zone: Challenges and Opportunities, Master Thesis, Addis Ababa University, July 2004
[46] Writing data to Xively, Available at: https://xively.com/dev/docs/api/data/write/
[accessed May 15, 2013] [47] Julien Labonne, Robert S. Chase. The Impact of Mobile Phones on Farmers’
Welfare in the Philippines, The World Bank, Sustainable Development Network Social Development Department, July 2009
[48] Jenny C. Aker and Isaac M. Mbiti. Mobile Phones and Economic Development in
Africa, Working paper, June 2010 [49] Charalampos Doukas. Building Internet of Things with the Arduino, 2012 [50] W. CHEBBI, M. BENJEMAA, A. KAMOUN, M. JABLOUN, A. SAHLI.
Development of a WSN Integrated Weather Station node for an Irrigation Alert Program under Tunisian Conditions, 2011 8th International Multi-Conference on Systems, Signals & Devices, 2011.
[51] Arduino Uno board, http://arduino.cc/en/Main/ArduinoBoardUno [Accessed June 14] [52] Arduino Ethernet shield. http://arduino.cc/en/Main/ArduinoEthernetShield