# Closed Loop Audio Test Suite

Simple Python-based testing system for PCB audio hardware validation.

## Features

- **Automated Testing**: Latency, THD, and SNR measurements across multiple frequencies
- **Metadata Tracking**: PCB version, revision, software version, timestamps, notes
- **YAML Output**: Human-readable structured results
- **Simple Workflow**: Run tests, view results, compare versions

## Quick Start

### 1. Install Dependencies

```bash
pip install -r requirements.txt
```

### 2. Run a Test

```bash
python run_test.py \
  --serial-number "SN001234" \
  --software-version "a3f2b1c" \
  --comment "Replaced capacitor C5"
```

### 3. View Results

```bash
# View specific test
python view_results.py test_results/20260226_123456_results.yaml

# List all tests
python view_results.py --list

# View latest test
python view_results.py test_results/*.yaml | tail -1
```

## Test Metrics

- **Latency**: Round-trip delay between input and output channels (ms)
- **THD**: Total Harmonic Distortion for input and output (%)
- **SNR**: Signal-to-Noise Ratio for input and output (dB)

Tests run at multiple frequencies: 100 Hz, 250 Hz, 500 Hz, 1 kHz, 2 kHz, 4 kHz, 8 kHz

## Output Format

Results are saved as YAML files in `test_results/`:

```yaml
metadata:
  test_id: 20260226_123456
  timestamp: '2026-02-26T12:34:56.789012'
  pcb_version: v2.1
  pcb_revision: A
  software_version: a3f2b1c
  notes: Replaced capacitor C5
test_results:
  - frequency_hz: 1000
    latency_ms: 2.345
    thd_input_percent: 0.012
    thd_output_percent: 0.034
    snr_input_db: 92.5
    snr_output_db: 89.2
```

## Configuration

Edit `config.yaml` to customize:
- Audio device settings
- Test frequencies
- Test duration
- Output options

## Hardware Setup

```
Laptop <-> Audio Interface (Scarlett) <-> DUT <-> Audio Interface (Scarlett) <-> Laptop
         Output Channels 1&2         Input Channels 1&2
```

The system auto-detects Focusrite Scarlett audio interfaces.

## File Structure

```
closed_loop_audio_test_suite/
├── config.yaml              # Test configuration
├── run_test.py              # Main test runner
├── view_results.py          # Results viewer
├── src/
│   └── audio_tests.py       # Core test functions
└── test_results/            # YAML output files
    └── YYYYMMDD_HHMMSS_results.yaml
```

## Tips

- Each test run creates a timestamped YAML file
- Results are self-contained with full metadata
- Compare tests by opening multiple YAML files
- Archive old tests by moving YAML files to subdirectories