The bus will glitch.  The dispenser will hang.
The field won't wait for your test plan.

Your device will fail in the field.
Find out how first.

Most test suites prove things work. HIL Tools proves what happens when they don't.

The gap in your test coverage

Protocol edge cases nobody thought to exercise. Power cycling behavior that was never characterized. Bus recovery paths that were never triggered deliberately. These are the gaps that show up in incident reports — and in expensive certification re-runs.

They go untested not out of negligence, but because without automated tooling, nobody runs the test. If it isn't scriptable and repeatable, it stays on the checklist and never gets checked.

HIL Tools makes the test something a developer actually runs.

Bus-level fault injection for embedded validation

$ hil run --bus i2c --fault glitch --addr 0x3C

  bus: I2C              output speed      100.000%
                        output accuracy   100.000%
  FPGA prep .......... complete

  scanning for 0x3C ... target found
  start condition asserted

  sending buffer
    bytes   1–158   nominal ................... sent

  ─────────────────────────────────────────────
    byte  159       glitch bit 5, hold 90µs
  ─────────────────────────────────────────────

  target response: NACK — error — recovering

  target log:
    Error on I2C bus — resetting
    Error on I2C bus — resetting
    Error on I2C bus — resetting
    ...

HIL Tools provides bus-level fault injection libraries for I2C, SPI, CAN, and UART/RS232. An FPGA-backed hardware platform drives deliberate error conditions — clock stretching, glitch injection, malformed frames, timing violations — while firmware on the device under test captures and reports actual behavior. The result is a documented response profile, not a pass/fail checkbox.

Every developer on the team runs the same fault injection suite. Failure modes get documented at a desk, not discovered in a certification lab. Current prototypes are running in three embedded pipelines.

Hydrogen dispensers. Medical devices. ASICs. Enterprise storage. Mesh radio. Thirty years of embedded validation work.

The common thread: teams that needed to know how their device fails, not just that it passes. HIL Tools is the library that came out of that work.

Working on a validation problem?

HIL Tools is in active development. If you're running embedded pipelines and need negative test coverage before a lab run, get in touch.

tk [at] hil.tools