The document describes the Sea-Bird Test Set DOSTS-1000, which was designed to automate testing of Sea-Bird Electronics' SBE 43 and SBE 43F Dissolved Oxygen sensors. The test set streamlines the testing process for technicians and reduces turnover times for sensor maintenance and repairs. It was designed with isolated circuitry to test the sensors' isolated circuitry and includes signal conditioning, a capacitor/resistor selector, power supplies, and a microcontroller. The hardware design includes a 4-layer PCB that controls automated testing through firmware, and the completed project deliverables include the prototype test set hardware and documentation.

1. Sea-Bird Test Set _DOSTS-1000
Michelle L Emmons, Steven Gaston & Colin Stefishen | Corporate Mentor: Vladic Simontov | Faculty Mentor: Dr. Eric Sortomme |University of Washington Bothell
Project Overview
The objective of this project is to design and prototype an automated test
bench for both the Sea-Bird Electronics SBE 43 and SBE 43F Dissolved
Oxygen sensors. The current need for this test bench is to minimize testing
time for technicians and to overall streamline the testing process. The
utilization of the proposed test set will be used in the manufacturing process
for final confidence checks before customer distribution. In addition the use
of the test set will lead to shorter turnover times for customers needing
maintenance and repairs resulting in lower labor-hour cost.
Acting as an Engineering Consultant team for the customer Sea-Bird
Electronics our team designed and prototyped the Dissolved Oxygen Sensor
Test Set-1000 (DOSTS-1000) from start to finish. The project was
accomplished through circuit design, PCB development, along with
computer programing the firmware. The project final deliverables include the
prototype and final DOSTS-1000 hardware, software and all technical
documentation.
Hardware Flowchart Design Concept
PCB Design Layout
Software Flowchart
Design
• Driven by isolated circuitry
• Main driving factor for the design
• SBE 43 and SBE 43F have circuitry
that needs to be isolated from ground
• Circuit design split between isolated
and non-isolated grounds
• Design split into main 4 parts
• Signal Conditioning
• Retrieval of analog signals from
test probes
• Converts analog signals to a range
that microcontroller can handle
• Capacitor/Resistor Selector
• Bank of capacitors and resistors
• Different combinations of are
selected based on test parameters
• Power Supplies
• Supplies power to entire circuit and
oxygen sensors
• Microcontroller
• Controls when and what signals are
to be measured
• Measures analog signals with ADC
and frequency counter
• Communicates with PC
PCB consists of 4 different layers and has an overall size of 9.5" x 5.5"
Hardware process for SBE 43 & SBE 43F automated board test
Above: Test set positioned in enclosure
Left: Test set PCB with all components mounted
Simplified Software Flow Chart shows the Logic of Firmware design. Firmware Tests are initiated by
receiving set strings from UART sent by User Interface. Depending on the test MUX Selection,
Capacitor Selection, and Resistor Selection will change. Firmware then reads the voltage or frequency
dependent upon test and adjusts to readable values. Then the results are sent back to the User
interface by UART communication.