Overview
Most firmware teams agree HIL is essential and have one engineer who maintains it during the time they can spare from shipping features. The suite drifts, coverage stagnates, and a quarter later it's “mostly green except for the tests we disabled.” Embedder treats HIL and SIL as a first-class codebase the agent generates, maintains, and runs alongside your firmware.
What this white paper covers
- Why HIL programs decay.
- Supported equipment — debug probes, logic analyzers, power profilers, bench gear.
- What Embedder generates — scaffolds, fixtures, regression sweeps.
- SIL alongside HIL.
- CI integration.
- Coverage and maintenance.
Why HIL programs decay
Writing a HIL test is more work than writing the feature it covers. The team writes one because they have to (certification, customer ask, a memorable incident), then the next ten features ship without one because the deadline is tighter. The suite slowly loses its ability to catch real regressions. The fix has to be that writing the test is roughly free. That's what the agent does.
Supported equipment
- Debug probes (GDB) — J-Link, ST-Link, OpenOCD.
- Logic analyzers — Saleae, Digilent (native data ingestion).
- Power profilers — Nordic PPK, Joulescope.
- Bench equipment — Siglent, Rigol scopes and programmable power supplies.
- Custom rigs — extensible adapters for proprietary fixtures.
- Universal data ingestion — exported captures from anything else.
What Embedder generates
- Test scaffolds — per peripheral, per feature, parameterized over the real hardware, written from the reference manual.
- Fixtures — power state, init sequence, expected pre/post conditions.
- Regression sweeps — for any change that touches a driver, run every test that exercises it.
- Bus-level verification — “is the PWM pair actually at the output pin?” — observed on the logic analyzer, not assumed from the driver.
- Coverage reports — by peripheral, feature, and condition, with traceability for regulated programs.
SIL alongside HIL
The same test definition runs against a simulator (for fast PR feedback) and the real board (for merge gates and nightly runs). You stop having two parallel test suites that drift apart.
CI integration
The same CLI your engineers use locally runs inside your CI runner. A typical setup:
- PR open — SIL runs, fast, all tests in a few minutes.
- PR ready for review — HIL runs on a board farm unit, posts results back to the PR.
- Merge — full regression sweep on hardware before the merge button unlocks.
- Nightly — long-running stress and soak tests across the board farm.
Coverage and maintenance
When a driver or schematic changes, the agent flags which tests are now stale, proposes updates, and runs the updated suite against the new board state. Your team approves the diff. The suite stops being a debt your one HIL engineer carries.
Who it's for
- Hardware teams shipping firmware to customers — every escape costs more than the test would have.
- Regulated programs — ISO 26262 ASIL, IEC 62304, DO-178C — needing documented test evidence per release.
- Teams with an existing HIL rig who can't keep coverage growing.
- Silicon vendors validating that generated drivers behave correctly at the bus level.
Getting started
Point us at your existing test setup. We'll show you what the agent does with one peripheral end to end. Talk to an engineer.