Soil Testing Data LoggerMid-Semester Presentation

February 22, 2011

Team Members

Cody Griffin

Op Am CircuitryVDIP CommunicationHardware TestingNormal Mode Design

Electrical Engineering

Daniel Herrington

Software Design LeadVDIP CommunicationSoftware TestingWebsite Design

Electrical Engineering

Ashley Stockbridge

RTCC Software DesignSetup Mode DesignNormal Mode DesignSoftware Testing

Electrical Engineering

Matt Weissinger

PCB DesignOp Amp CircuitryHardware TestingComponent Research

Electrical Engineering

Outline

• Background• Problem• Solution• Constraints

– Technical– Practical

• Progress and Refinements• Packaging• Testing Plan• Production

Background – Soil Redox Potential

• Electrical property of soil that correlates to the specific chemicals present in the ground

• Research topic of Dr. Kroger with the Forest and Wildlife Research Center at MSU

Problem – Chemical Runoff

• Caused by fertilizers and pesticides used on farmlands

• Can be controlled using a detailed historical set of soil redox data

• No efficient method for collecting soil redox measurements

Solution – Soil Testing Data Logger

• Reduces the time associated with taking soil redox potential measurements in the field

• Periodically takes soil redox potential and associated temperature measurements

• Stores all measurements in a removable USB storage device

Technical Constraints

Constraint Description

Inputs The device must support four soil probe inputs and five temperature inputs.

Soil Redox Potential Input Range

The device must be able to measure potentials that range from -600mV to +600mV with an accuracy of ±10mV.

Temperature Indicator Input Range

The device must be able to measure temperatures that range from -40°C to 125°C with an accuracy of ±1°C.

Data Storage The device must store soil redox potential and temperature data on a removable USB storage device.

Sample Rate The device must store sample data every 20 minutes.

Practical Constraints

Type Constraint Description

Manufacturability Size The size of the circuit board must be no larger than 3.1” x 3.9”.

Environmental Operating Conditions The device must be able to operate in extreme weather conditions.

Manufacturability

• No larger than 3.1” x 3.9”• Easily accessible for routine maintenance• Organized for easy assembly

Environmental

Cleveland, MS

Progress and Refinements

• PCB Refinements– Added third RJ45 connection– Added programming header– Minor silkscreen changes

• Manufactured initial set of soil probes• Added software start-up delay• Conducted initial laboratory testing

PCB Refinements

• Allows for grouping of soil/temp probe pairs• Lowers difficulty of manufacturing soil/temp probes

Manufactured Soil / Temp Probes

• Soil / Temp probes are waterproofed using:– RJ45 cables– Heat shrink– Water tight sealant

Packaging

• PCB is final packaging for data logger• Soil and temperature probes will be

manufactured by the team

Testing Plan

• Completed:– Short Term Laboratory Test– Short Term Field Test

• In Progress:– Long Term Field Test

Temperature Testing Data

Soil Redox Probe Testing Data

Production

• After changes to PCB have been finalized, new PCB will be fabricated and populated

• Additional data loggers and soil / temp probes will be manufactured at Dr. Kroger’s request

References

[1] “Season Weather Averages for Mid Delta Regional,” Weather Underground. 2010. http://www.wunderground.com/NORMS/DisplayNORMS.asp?AirportCode=KGLH&SafeCityName=Cleveland&StateCode=MS&Units=none&IATA=GLH

Questions?Questions?