Why Documentation Matters

Introduction

Documenting a design is a fundamental aspect of the design process. This should always be undertaken before prototypes are created and never retrospectively. In this article, I am going to explore when certain documentation tasks should be actioned and what documentation is required on the journey from a concept to production.

Initial Design

Following on from the requirements specification, detailed design documents for the electronic components for the system should be created. This allows a central point of information for a design. A System Architect, along with an electronic design engineer, should take the responsibility for implementing this. At Conficio, this typically contains system diagrams, functional block requirements, component justification and usage.?

As more information finds its way into this document, the more useful it becomes to other team members. Often, the software engineers will be extracting information, such as ADC scaling factors and peripheral selections, to avoid having to extract data from the schematic, often having to re-do calculations that have already been done.

Software design has many tools available to outline code, some will even auto-generate software. Initially, Conficio will create a filing system that contains the driver, HAL and system files. The code-base is started using Doxygen as a documentation platform. Doxygen allows our engineers to create HTML documentation from the comments within the source code.

Undertaking a detailed design stage will also reduce the implementation time. The detail within the design will have already been explored, this reduces the effort required by the engineer to search multiple datasheets and multitask. In turn, this reduces mistakes and can actually streamline the entire design process.

Concise documentation can be used as a requirement specification for passing between skilled engineers and junior engineers to maximise the use of resource within the project and company scope.

Maintenance

The most critical aspect to any documentation is ensuring that it is kept up to date. This might sound obvious but during fast iteration cycles it can often be missed out. If a project needs to be paused, either internally or externally, having up to date design resources reduces the pickup time. In a worst-case scenario, this allows for a more seamless transition between internal and external resources to minimise the impact to the client.

At each manufacturing stage, the detailed design documents should be updated. This ensures that there is a snapshot of the design for retrospective analysis and ongoing support of specific versions. Documentation maintenance is often fed by design reviews of prototypes and the finding of other departments within an organisation.

Reviews

After the implementation of a design, a number of reviews are required to reduce the iterative prototyping loop. In terms of the electronics, Schematic Reviews and Layout Reviews between the System Architect, PCB Engineer and Firmware team ensure that the interfaces and implementations are as expected. For Industrial Design, draft angle reviews, collisions checks (between both the PCB and other components) and manufacturing reports reduce the chances of rework of plastics. Each item that is identified in the review will be documented, and the fix recorded.

Reviewing work is essential for the QA process. Creating a system that has traceability of decisions and implementations helps maintain a Technical File that is suitable for Certification.

Manufacture

Documentation does not only consist of written text and diagrams, but also manufacturing packs. These are critical to link the computer-based design to physical product.

In order to engage with a PCB manufacturing company, [see here] production documentation is required. This typically consists of a PCB specification, Gerbers and BoM. These will be reviewed by the manufacturer before commencing to ensure that the board can fundamentally be assembled.

Generally, a 3D printing company [such as this] can use 3D exports from SolidWorks or fusion 360. However, a Tooling supplier will also require the technical drawings to ensure that the plastics produced are within tolerance.

At the end of the design process, i.e. the start of manufacture, the final documentation pack will extend to include items such as firmware, test procedures and assembly instructions. Both the test procedure and assembly instructions will be reviewed with our client, the assembly house and Conficio. During this review, our engineers will ensure that the documentation is suitable for and understood by the assembly house. Optimisations to the final production documentation may be made at this time or after the first production run.

Certification

Before product release it is important to ensure that the technical file is suitable for CE and UKCA marking. This technical file will consist of reports from third party test facilities [such as this] the design documentation and verification documents. The technical file is required to show that the product is both safe and fit for purpose. Putting a CE and UKCA mark onto a product shows that the owner has understood the requirements and standards of the market sector and applied due diligence to meeting those.

Life Cycle Maintenance

Documentation continues to be useful to a product owner during the product life cycle. It is inevitable that at some point a product will be damaged and require repair. The manufacturing documentation and test procedures can play an important role in determining the cause of the malfunction and the appropriate actions to fix the issue. Providing good after sales support can ingratiate a company with an end user and create true brand loyalty.

Although we design with best practice and select components that are likely to continue to be manufactured, situations where items become obsolete or unavailable do arise. At this point, having a detailed design document will help to identify replacement components that may be drop in or at least minimise the impact on the remaining part of the product.

At the end of the product lifecycle, documentation can help to determine if and how certain parts of a product can be recycled or reused. As the requirements for sustainable products become more desirable more companies will be required to consider disposal.

Conclusion

Although creating design documentation may feel arduous and un-required, it is critical to reducing long term costs and justifying the product. Our team use best practices to create documentation that is concise, controlled and useful. Documentation is there to facilitate the design process rather than be detrimental to it.

To find out more about our design practices and resources, please visit our website or email us at [email protected].

Author: Jon Reece [System Architect at Conficio Product Design ]