What Happens When You Start Testing Earlier

Simon Payne, CEO, XJTAG | Subscribe to LinkedIn newsletter

electronics manufacturing production line

Over the past few months, we’ve been talking about the importance of proving hardware early during bring-up.

Not just debugging when something goes wrong, but establishing confidence in the system before problems have a chance to grow.

Recently, we saw a very clear example of what happens when that approach is applied consistently.

The Starting Point

An engineering team working on complex electronic assemblies wanted to improve their test process.

Their goals were straightforward:

Reduce test development time
Improve fault diagnosis
Maintain high coverage and reliability
Scale across multiple product lines

Nothing unusual there, these are challenges many teams face.

The Traditional Problem

In many environments, testing and debugging happen relatively late in the process.

Boards are assembled
Firmware is developed
Functional testing begins

And only then do issues fully surface. At that stage, diagnosing faults can be slow and expensive.

A Different Approach

Instead, this team shifted testing earlier in the lifecycle.

They introduced structural testing and programming:

during early prototypes
throughout development stages
and across production

This meant that boards could be validated:

as soon as they were assembled
before full system behaviour was introduced
and repeatedly as designs evolved

What Changed

The impact was significant.

Test development became much faster, with reusable libraries reducing creation time to around 40–60% of previous levels.

Fault diagnosis also improved dramatically.

Issues that previously took hours to identify could now be located in minutes and much earlier in the process, often immediately after assembly.

At the same time, integrating programming into the test process reduced overall production costs by 20–30% by removing the need for additional test fixtures.

What’s Really Happening Here

This isn’t just about faster tools or better automation, it’s about a change in approach.

Instead of waiting for problems to appear during functional testing, the team focused on proving the hardware earlier:

confirming connectivity
validating device access
ensuring configuration paths were working

By doing that, they reduced uncertainty. And once that uncertainty was removed, everything else became easier:

debugging became faster
development cycles shortened
production became more predictable

A Broader Pattern

This aligns closely with what we’ve been discussing over the past 12–13 weeks. The biggest gains in bring-up don’t always come from solving problems faster.

They often come from proving the right things earlier.

Closing Thought

In complex FPGA systems, problems are inevitable. But the point at which you discover them and how clearly you can isolate them makes all the difference.

Testing earlier, and across more stages of the lifecycle, doesn’t just improve quality, it fundamentally changes how quickly you can move forward.

Full Case Study

If you’d like to see the full details behind this example, you can read the case study here.

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Don’t Throw Away the Tests That Got Your Prototype Working The first prototype arrives and the engineering team begins the process of proving the hardware. Connections are checked. Memories are exercised. Peripherals are tested. Problems are found, understood and fixed. Eventually, the board works. And then something slightly strange can happen. Much of the test capability that helped get it working is never used again. Bring-Up Creates More Than a Working Board During bring-up, engineers build up a significant amount of knowledge about the hardware. They learn how to initialise devices. They discover which signals need to be controlled. They find ways of checking memories and peripherals. They work out how to distinguish between a software problem and a hardware problem. Sometimes this knowledge becomes a formal test. Sometimes it is a small utility written by one engineer. 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Structural tests developed during prototype bring-up don't necessarily need to be discarded once the design is working. Tests that proved connectivity, memories, peripherals or interfaces during development may also provide useful coverage in production. That means the effort invested in understanding the first prototypes can potentially become part of the manufacturing test strategy. Instead of starting again, knowledge moves forward with the product. Closing Thought A string of passing boards doesn't really test your diagnostic strategy. The first failure does. That is when you discover whether your test simply detects a problem or actually helps the engineer understand it. And the difference between knowing: “This board failed.” and: “This is where you should start looking.” can determine whether the problem is diagnosed in minutes, investigated for hours or placed on a growing bone pile marked: Investigate later. The best production tests don't just catch faults. They help engineers understand them. Board Design Tip of the Week Before releasing your next design, choose three realistic manufacturing faults. For example: An open connection beneath a BGA A short between two adjacent signals An incorrectly fitted peripheral Then ask: “If this happened on the production line, what would our test actually tell us?” If the answer is simply: FAIL there may still be work to do. Discover more about your board design with the Free XJTAG Layout Viewer. To get started find out how the Free XJTAG Layout Viewer can help you see on your board: Download your Free XJTAG Layout Viewer today