Problem statement: Significant effort goes into the development of biomedical software, which is integrated with computers/processors, sensors and electronic instrumentation devoted to a specific application. However, the scientific work on electronic instrumentation controlled by biomedical software has not emphasized software development, instead focusing mainly on electronics engineering. The development team is rarely composed of Software Engineering (SE) experts. Usually, a commercial automated tools environment is not used due to its high cost and complexity for researchers from other areas to understand. Approach: This present study reports how the SE approach was applied to design and develop biomedical software, which is part of a Computerized Electronic Instrumentation (CEI). This CEI comprises software and an electronic instrumentation based on a force sensor and electrogoniometer to monitor the hand exertion of computer user during typing task. The aim is to serve as a guideline for academic researchers who are not expert in software engineering methodology but usually develop their own software to run with their CEI. The specification of the requirements, presented as use case, includes the context diagram, the data flow diagram, the entity relationship diagram and test procedure. The Unified Modelling Language from the Enterprise Architect tool was used. The developed software and the electronic instrumentation were tested together. Results: A sample of the interface screen shows how the outcomes could be plotted in an integrated manner. By comparing the values with other values obtained by manual calculations and with those provided by sensor manufacturer, the repeatability of test procedure validated the results. Reliable electronic instrumentation when working with unreliable software can become unreliable. Conclusion: Applying software engineering methodology principles provided a simple and clear documentation that was helpful to establish the test procedures and the re-work.