Soil Testing Data Logger Mid-Semester Presentation February 22, 2011

Team Members Cody Griffin Op Am Circuitry VDIP Communication Hardware Testing Normal Mode Design Electrical Engineering Daniel Herrington Software Design Lead VDIP Communication Software Testing Website Design Electrical Engineering Ashley Stockbridge RTCC Software Design Setup Mode Design Normal Mode Design Software Testing Electrical Engineering Matt Weissinger PCB Design Op Amp Circuitry Hardware Testing Component 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 ConstraintDescription InputsThe 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 StorageThe device must store soil redox potential and temperature data on a removable USB storage device. Sample RateThe device must store sample data every 20 minutes.

Practical Constraints TypeConstraintDescription ManufacturabilitySizeThe size of the circuit board must be no larger than 3.1” x 3.9”. EnvironmentalOperating ConditionsThe 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 veland&StateCode=MS&Units=none&IATA=GLH veland&StateCode=MS&Units=none&IATA=GLH

Questions?