TESTCOUPON

Describe a board. Get one you can argue with.

TestCoupon turns a written description into a spec you correct, then compiles that spec into a real KiCad project, then checks it and tells you what it could not check. The generating is the easy half. Everything here exists to make the generating trustworthy.

projects/laser-driver · check · 2026-07-29
PASS
0 errors  0 warnings  ·  7 rules run, 0 waived  ·  ERC clean  DRC clean  parity clean  ·  76/76 pins matched

That is a real result on a real board, and it is clean. The board still had nine defects and would not have powered on. This is why the pipeline is shaped the way it is.

Every line below is a part fitted the wrong way round, wired to a pin that does not exist, or ordered as a description rather than a part you can actually buy. None of it is exotic. All of it came from someone trusting what they remembered about a component instead of opening its datasheet.

U1TPS61023 boost converter. Not one pin of six matched the real SOT563 pinout, and the package was wrong too.
U3REF3312 reference. GND and OUT transposed.
D2Monitor photodiode reversed. Forward biased, so VMON reads high in the dark and the laser never turns on.
D3BAT54 clamp wired to a pin the part does not have. The independent overdrive protection went nowhere.
D4TVS reversed across the emitter, shunting it.
D3Two‑pad footprint on a three‑lead package. Unbuildable as drawn.
BOMA part stamped discontinued, already carrying the watermark when it was chosen.
BOMA placeholder value where an orderable part number belongs.
R7 R8Enable divider at 1.0 V against a 1.2 V guaranteed minimum. Cuts out near end of battery life, and only then.

Every one of those came from a part interface being assumed instead of retrieved. None of them were findable by ERC, DRC, schematic parity, or the house rules, because all of those check the capture against itself. Nothing in them knows what pin 3 of a real part does.

TestCoupon is what got built after that board. It is in private alpha behind an invite gate.

How it works

Four steps, in order, because each one refuses to run until the one before it holds up. That refusal is the product.

  1. 01

    Say what you are building, in a sentence

    “A 940nm illuminator for night vision, battery powered, has to reach 300m.” What comes back is a draft spec: every value tagged with where it came from, and everything the model could not support marked as a guess rather than quietly presented as an answer. It also lists what it should have asked you and did not.

  2. 02

    Argue with it until it is right

    “You never picked switching versus continuous drive, the battery will die fast.” It revises and tries again, for as many rounds as you want. Every round is kept, so the wrong first draft survives next to the corrected one and the reasoning is recoverable later.

  3. 03

    It compiles the spec into a board

    A typed block description becomes a real KiCad schematic and layout. The build is refused outright while any safety-relevant field in the spec is still a guess, so design effort is never spent underneath an assumption nobody checked. A refusal is not a failure; it is the gate doing the one thing it is for.

  4. 04

    Then it checks the board, and says what it skipped

    KiCad’s own electrical and design rule checks, house rules for what those two do not look at, and every part compared against the pin table in its manufacturer’s datasheet. Alongside the findings: what the run did not examine, so a short list can never be mistaken for a clean board.

Why the gate matters more than the generator

Generating a plausible circuit is not hard, and that is the problem. Across 115 failed machine-synthesized designs, error rate rose with circuit size at r = 0.863: the bigger the thing you ask for in one go, the more of it is wrong. A generator that answers confidently at any size is not a feature.

So nothing here is synthesized a whole board at a time, nothing is built from a spec that has not cleared its gate, and no part reaches a netlist without its pin numbers having been read out of the manufacturer’s own datasheet and recorded. The board at the top of this page is what the alternative looks like.

What a finding looks like

Findings are graded, and the grades mean specific things. An error is something that will not work. A warning is something worth an argument. The checker also reports whether it finished at all, separately from what it found, so a run that broke halfway through says so instead of quietly reporting nothing wrong.

■ ERROR  decoupling-proximity  U1  127.25, 116.73
U1 pad 2 is on power net ‘VDDA’ which has no cap within 2.00 mm

Where defects actually are

Shares of 115 failed LLM‑synthesized designs, by category. This is the order the review checklist is worked in, most common first, rather than top‑to‑bottom through the schematic. It is also an honest map of what the rule pack does and does not reach.

59%
Wrong supporting components rules reach this
40%
Wrong interfaces pin maps reach this
34%
Wrong values human read
27%
Wrong local topology human read
23%
Wrong configuration human read

Provenance, per part

A pin map is only worth what the document behind it is worth. Every part carries the document number, revision, and hash of the file the pins were read from, fetched from the manufacturer's own domain. Aggregator and reseller mirrors are refused, because a mirror cannot tell you authoritatively which revision you are reading.

mpn
TPS61023
manufacturer
Texas Instruments
document
SLVSF14B  rev B  revised 2020-08
url
ti.com/lit/ds/symlink/tps61023.pdf
sha256
b181cbe9e2d37cbea98a445586a4650fff38247d7142749db08d492a7836aa68
retrieved
2026-07-29
pins from
page 3, “Pin Functions”

What it does not do

A gate that passes everything manufactures false confidence, and so does a page that only lists what a gate catches. These are the current limits, and they are kept in the repository as a file that has to be updated in the same change that adds a skip or a waiver.

Why it is called that

A test coupon is a real thing. Board fabricators carry a small extra strip along the edge of every panel, built in the same run as the boards themselves. It gets cut off, sliced through, and measured, so the plating and the drilling can be checked without destroying anything anyone paid for.

It is the part of the panel that exists to be tested instead of trusted. That is the mark above, and it is the whole idea.

Private alpha

Creating an account joins the waitlist. There is no trial to start and nothing to configure yet; access is granted by invite while the rule pack is still being built out.