analog-hw-measure

Analog HW Measure

Drives the measurement instruments (oscilloscope + FPGA ADC) to capture real analog block behavior, then parses the results into a structured measurement report comparable to SPICE simulation output.

When to use

• After analog-hw-testbench-gen has programmed the FPGA
• When the user says "measure the LDO output", "capture scope waveform"
• During analog-hw-tuning-loop iterations

Inputs

1. analog/<block>/spec.json — specs with min/max limits
2. analog/<block>/hw_test/pin_assignments.qsf — which scope channel maps to which signal
3. Scope connection info (default: lab at )
4. FPGA ADC channel mapping

MCP tools used

Tool	Purpose
device_scope_capture	Capture transient waveform (CSV: time, voltage)
device_scope_periodic_pulse_check	Measure frequency, duty cycle, amplitude
eda_fpga_adc_read	Read MAX10 ADC for DC voltage (when available)
device_camera_led_diff	Capture LED pass/fail indication

Measurement types per block

Block type	Key measurements	Instrument
LDO	Vout DC, load regulation, PSRR, transient response	ADC (DC) + Scope (transient)
Oscillator	Frequency, duty cycle, jitter, startup time	Scope (periodic)
POR	Trip voltage, hysteresis, release delay	Scope (single-shot ramp)
Bandgap	Vref DC, temperature coefficient	ADC (DC, sweep temp manually)
Comparator	Propagation delay, offset, hysteresis	Scope (transient)

Workflow

1. Verify FPGA is programmed and scope is connected
2. For each spec in spec.json: a. Configure scope timebase and trigger (via stimulus controller) b. Trigger measurement sequence on FPGA c. Capture data via appropriate MCP tool d. Parse captured data → extract metric e. Compare against spec limits → PASS/FAIL
3. Aggregate all measurements into report

Waveform parsing

The DC/rise/settling/overshoot/freq/jitter math below is FIXED and deterministic — do NOT re-derive it by hand each run. Once you have a captured scope CSV (time,voltage), invoke the program so the numbers come out identically every time:

python3 programs/scope_waveform_metrics.py <scope_csv> \
    [--spec analog/<block>/spec.json] [--json analog/<block>/hw_measurements.json]

It emits {dc_level, rise_time, settling_time, overshoot, freq, jitter} and, when a spec JSON with per-metric min/max is given, a per-spec PASS/FAIL (a metric that cannot be computed grades SKIP, never a false FAIL). Exit 0 = extracted / all gradeable specs PASS, 1 = a spec FAILed, 2 = IO/parse error. The program degrades gracefully: a capture shorter than --min-samples (default 8), with no detectable edge, or non-periodic reports the affected metric as null + a MISSING/SKIP note instead of guessing.

The frozen formulas it implements (kept here for reference / review only):

• DC level: mean of last 20% of capture window
• Rise time: 10%-90% transition time
• Settling time: time to stay within ±2% of final value
• Overshoot: (peak - final) / final × 100%
• Frequency: FFT peak or zero-crossing period measurement (the program uses the deterministic mean-crossing-period path)
• Jitter: std dev of period over N cycles

AI judgment stays with you — choosing the right instrument per block (scope transient vs ADC DC vs periodic-pulse), setting timebase/trigger, deciding when a capture is trustworthy, and interpreting a SKIP/MISSING metric (re-capture vs accept) are NOT delegated to the program. The program only freezes the arithmetic on a capture you already judged good.

Output format

analog/<block>/hw_measurements.json

{
  "block_name": "ldo_1v8",
  "timestamp": "2026-04-29T14:30:00Z",
  "measurements": {
    "vout_dc": {"value": 1.803, "unit": "V", "spec_min": 1.75, "spec_max": 1.85, "status": "PASS"},
    "load_reg": {"value": 0.5, "unit": "%", "spec_max": 2.0, "status": "PASS"},
    "settling_time": {"value": 12.3, "unit": "us", "spec_max": 50, "status": "PASS"}
  },
  "scope_files": ["analog/ldo_1v8/hw_test/scope_transient.csv"],
  "all_pass": true
}

Do not

• Do not assume scope is always available — check connection first and report gracefully if offline
• Do not overwrite previous measurement files — timestamp or version them
• Do not interpret ADC readings without calibration (MAX10 ADC has ±2 LSB offset)

Handoff

• hw_measurements.json → analog-hw-tuning-loop for three-way comparison
• Scope CSV files → scope_response_byte_decode_check (if protocol testing)
• If any measurement FAIL → report to tuning loop for sizing adjustment

Compliance gate (mandatory)

After producing your output, save it to a file and run:

python3 plugins/vibe-ic/_shared/skill_compliance_check.py \
    --requirements plugins/vibe-ic/skills/analog-hw-measure/compliance.yaml \
    <your_output_file>

Exit 0 = PASS, exit 1 = FAIL with specific missing elements listed.

Your task is not complete until the audit returns PASS.