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EarLink Test Bench: How We Tamed the Chaos
Today feels like a small holiday for our team. After several days of work, countless cups of coffee, and a couple of soldering iron burns, we finally built the test bench for the main EarLink board.
The phrase “test bench” sounds modest, but in reality it’s a full software-hardware complex — and a huge leap forward for the product.
Imagine your kid suddenly learned to steal headphones… One morning, a teammate had no clue what just happened — because, well, we work with Bluetooth :DDDD
In complex electronics development, a bench isn’t a toy for engineers. It’s insurance against human error, random mistakes, and the subjective “hmm, feels better now.” Our lab bench is ready! :))
How to Achieve Perfect Sound Quality?
The problem? Engineers are human: tired, error-prone, and always carrying a pocketful of static electricity. One clumsy finger tap, and the chip turns into a brick.Trust us, we are actually finalize that trick.
Before, testing meant: the engineer manually compiled firmware, connected wires, launched the test, logged results, and then decided by eye whether it worked.
So we came to the conclusion: let robots work, let humans be happy.
Our test bench solves the pain points automatically:
- Removes the risk of killing electronics with static discharges.
- Saves connectors from endless plugging/unplugging (the fastest way to destroy any hardware).
- Turns results into numbers and graphs — we use bit shifting and quadratic functions for the math.
People hear sound differently. Numbers don’t lie. ;)
Architecture: Two Computers, One Board in the Middle
We built the bench on a “infrastructure as a code” principle:
- Builder PC in cloud + our pipelines — compiles firmware from source, launches and controls all processes, and logs results to the database.
- Microcomputer — the loyal sidekick. Connected directly to the board lines, it does the dirty work: recording low-level signals, emulating user actions (like powering on or “pressing a button”) and for sure flashing PCB in case where OTA falling.
At the center — our PCB, the heart of EarLink. It must work in harmony with both software and hardware, and the bench is there to check how well they communicate.
The Bluetooth Triangle
EarLink is a Bluetooth bridge between devices — in three directions at once:
- Mobile phone ↔ EarLink
- EarLink ↔ Headphones
- EarLink ↔ PTT button / remote controls (play/pause, push-to-talk, etc.)
All three channels must work flawlessly. Otherwise, instead of pure sound, the user hears a “symphony” of clicks and hiss. (Hopefully you’ve never heard a falling hearing aid.)
How We Measure “Sound Quality”
Look at headphone spec sheets and you’ll see frequency ranges, distortion coefficients, output power, and other geeky stuff. All of that comes from test benches.
In our setup:
- Microcomputer pretends to be both the phone and the headphones, using two different Bluetooth adapters.
- EarLink sits in the middle (like a race car on a dyno).
- We play audio, pass it through the device, and then compare input vs. output.
The result? A clean mathematical evaluation of how much EarLink “touched” the sound. Transparent, fair, and free of the “engineer’s ear” bias.
Results
We built a tool that doesn’t get tired, doesn’t make mistakes, and doesn’t complain. With it, we can move faster and more confidently — which means EarLink will be better than it ever could have been without it.
Creating the test bench means we now have one magical button — “build & test everything”. Behind it lies a ton of hardware, software, databases, and system tweaks. But the payoff is worth it:
- Engineers no longer fry boards with their fingers.
- Tests are reproducible.
- Results can be compared and analyzed.
- Development cycles are dramatically faster.
We managed to tame entropy in our little corner.
Chaos defeated.
Results made clear.
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