altium-scripts/README.md

# Altium Scripts

**Convention:** All Python scripts use **.env** for input/output paths (and optional settings); you can override any value via **CLI**. All scripts write JSON output to the **`outputs/`** folder by default. Copy `.env.example` to `.env` and edit.

---

## Capacitors by net pair

**Script:** `CapacitorsByNetPair.pas`

Finds all **two-pad components** on the PCB that share the same two nets (e.g. decoupling capacitors between VCC and GND). Outputs a JSON file with:

- **Key:** net pair (e.g. `"GND|VCC"`), sorted so the same pair is always grouped
- **Value:** for each net pair:
  - List of capacitors: designator, value string, package (footprint), and capacitance in farads
  - **Total capacitance** for that net pair (sum of all caps between those two nets)

### How to run

1. Open your **PcbDoc** in Altium Designer.
2. **DXP → Run Script…** (or **File → Run Script…** depending on version).
3. Browse to `CapacitorsByNetPair.pas` and run it.
4. Choose a save location for the JSON file when prompted.

### JSON output format

```json
{
  "GND|VCC": {
    "total_capacitance_F": 2.2e-05,
    "total_capacitance_str": "22uF",
    "capacitors": [
      {
        "designator": "C1",
        "value": "10uF",
        "package": "0805",
        "capacitance_F": 1e-05
      },
      {
        "designator": "C2",
        "value": "12uF",
        "package": "0805",
        "capacitance_F": 1.2e-05
      }
    ]
  },
  "GND|VDD": {
    "total_capacitance_F": 1e-06,
    "total_capacitance_str": "1uF",
    "capacitors": [
      {
        "designator": "C10",
        "value": "1uF",
        "package": "0603",
        "capacitance_F": 1e-06
      }
    ]
  }
}
```

### KiCad .kicad_pcb (Python script)

**Script:** `capacitors_by_net_pair.py` — **KiCad only.** Reads a `.kicad_pcb` file and outputs the same JSON (net pair → capacitors with designator, value, package, total capacitance).

**Usage:**

```bash
python3 capacitors_by_net_pair.py board.kicad_pcb
python3 capacitors_by_net_pair.py board.kicad_pcb -o outputs/capacitors_by_net_pair.json
```

**Input/output from .env:** Set `INPUT_FILE` and `OUTPUT_FILE`; CLI overrides. Default output: **`outputs/capacitors_by_net_pair.json`**.


---

## Compare component locations (two KiCad files)

**Script:** `compare_protel_locations.py`

Loads two KiCad `.kicad_pcb` files and reports **which components have moved** between them. Component position is the centroid of pad `(at x y)` coordinates. Output is written to `outputs/compare_locations.json` by default.

- **Moved:** designators with different (x, y) in file2, with old position, new position, and distance.
- **Only in file1 / only in file2:** components that appear in just one file.

**Usage:**

```bash
python3 compare_protel_locations.py board_v1.kicad_pcb board_v2.kicad_pcb
python3 compare_protel_locations.py board_v1.kicad_pcb board_v2.kicad_pcb -o outputs/compare_locations.json
```

Use **.env** (optional): set `FILE1`, `FILE2`, and `COMPARE_OUTPUT`; CLI arguments override them. Use `--threshold N` to set the minimum position change to count as moved (default 1.0).

---

## Spreadsheet diff by designator

**Script:** `diff_spreadsheets.py`

Compares two spreadsheets (`.xlsx` or `.csv`) on a designator column. Data is read **from row 10** by default (first 9 rows skipped). Outputs which designators are only in file1, only in file2, or in both.

**Usage:**

```bash
pip install pandas openpyxl
python3 diff_spreadsheets.py sheet1.xlsx sheet2.xlsx -o outputs/spreadsheet_diff.json
```

Options: `--designator-col 0` (0-based column index), `--start-row 9` (0-based; 9 = row 10). Env: `SHEET1`, `SHEET2`, `DIFF_OUTPUT`.

**Test:** `tests/sheet1.csv` and `tests/sheet2.csv` (designators from row 10):

```bash
python3 diff_spreadsheets.py tests/sheet1.csv tests/sheet2.csv --start-row 9
```

---

## Find bottom termination parts (QFN, DFN, BGA) by description

**Script:** `find_bottom_termination_parts.py`

Reads the same spreadsheet format (designator column, data from row 10) plus **description** and optionally **package** columns. Finds components whose description or package indicates **bottom termination**, including:

- **Package types:** QFN, DFN, BGA, LGA, SON, MLF, MLP, WDFN, WQFN, VQFN, etc.
- **Generic:** “bottom termination” (e.g. with 0201 or 0402)

Outputs matching designators, description, package, and the matched pattern to `outputs/bottom_termination_parts.json`.

**Usage:**

```bash
python3 find_bottom_termination_parts.py sheet.xlsx --description-col 1
python3 find_bottom_termination_parts.py sheet.xlsx --description-col 3
```

Env: `SHEET`, `BOTTOM_TERM_OUTPUT`, `DESCRIPTION_COL` (default 1), `START_ROW` (default 9). No package column; only description is searched.

**Test:** `tests/sheet_with_descriptions.csv` (description col 3):

```bash
python3 find_bottom_termination_parts.py tests/sheet_with_descriptions.csv --description-col 3 --start-row 9
```

### Notes

- Only components with **exactly two pads** (each on a net) and **designator starting with `C`** are included (treated as capacitors). To include all two-pad parts, edit the script and remove the `And (UpperCase(Copy(Component.Name.Text, 1, 1)) = 'C')` condition.
- Capacitance is parsed from the component **Value** parameter (e.g. `10uF`, `100nF`, `22pF`) and totalled in farads. Supported suffixes: F, mF, uF/µF, nF, pF.
- Package is taken from the component’s **Pattern** (footprint) name.
- If your Altium version uses different parameter or footprint property names, you may need to adjust the script (e.g. `DM_ComponentParameterName` / `DM_ComponentParameterValue`, or `Pattern` vs `Footprint`).