freechips/semicustom/semicustom-inverter.ipynb

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   "source": [
    "# Semicustom digital design demo using OpenROAD"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Sources"
   ]
  },
  {
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   "metadata": {
    "id": "uINjDJNf39eD"
   },
   "source": [
    "### RTL description (Verilog)\n",
    "\n",
    "The OpenROAD workflow takes the circuit's RTL description as an input. For instance, it can be a three bits XOR gate."
   ]
  },
  {
   "cell_type": "code",
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   "source": [
    "%%writefile inverter.v\n",
    "module inverter(\n",
    "    input wire a,\n",
    "    input wire b,\n",
    "    input wire c,\n",
    "    output wire out\n",
    ");\n",
    "    assign out = a ^ b ^ c;\n",
    "endmodule"
   ]
  },
  {
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   "source": [
    "### Configuration file (JSON)\n",
    "\n",
    "A configuration file should be provided. It describes constraints and strategies applied during synthesis and implementation of the circuit."
   ]
  },
  {
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   "source": [
    "%%writefile config.json\n",
    "{\n",
    "    \"DESIGN_NAME\": \"inverter\",\n",
    "    \"VERILOG_FILES\": \"dir::inverter.v\",\n",
    "    \"CLOCK_TREE_SYNTH\": false,\n",
    "    \"CLOCK_PORT\": null,\n",
    "    \"PL_RANDOM_GLB_PLACEMENT\": true,\n",
    "    \"FP_SIZING\": \"absolute\",\n",
    "    \"DIE_AREA\": \"0 0 40 40\",\n",
    "    \"PL_TARGET_DENSITY\": 0.8,\n",
    "    \"FP_PDN_AUTO_ADJUST\": false,\n",
    "    \"FP_PDN_VPITCH\": 10,\n",
    "    \"FP_PDN_HPITCH\": 10,\n",
    "    \"FP_PDN_VOFFSET\": 5,\n",
    "    \"FP_PDN_HOFFSET\": 5,\n",
    "    \"DIODE_INSERTION_STRATEGY\": 3\n",
    "}"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Workflow\n",
    "The provided `flow.tcl` is a script describing the OpenROAD workflow. A _GDS_ file will be generated using the RTL circuit description, the PDK and the configuration file."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
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     "base_uri": "https://localhost:8080/"
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    "id": "VP60fdObiP15",
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   "source": [
    "%env PDK=sky130A\n",
    "!flow.tcl -design ."
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Output products"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {
    "id": "luguFgZ43AeL"
   },
   "source": [
    "### Display layout\n",
    "\n",
    "The implemented layout can be retrieved as follows:"
   ]
  },
  {
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   "outputs": [],
   "source": [
    "import glob\n",
    "import gdstk\n",
    "import IPython.display\n",
    "\n",
    "gdsii = sorted(glob.glob(\"./runs/*/results/final/gds/*.gds\"))[-1]\n",
    "top = gdstk.read_gds(gdsii).top_level()\n",
    "top[0].write_svg('inverter.svg')\n",
    "IPython.display.SVG('inverter.svg')"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {
    "id": "NW_7YdgTZYQK"
   },
   "source": [
    "### Reporting\n",
    "\n",
    "Many reports are available under:\n",
    "\n",
    "```\n",
    "freeechips/semicustom/runs/RUN_YYYY.MM.DD_HH.MM.SS/reports/.\n",
    "```\n",
    "\n",
    "An overview of the main figures can be retrieved as well:"
   ]
  },
  {
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    "outputId": "d50dcf9f-30cd-42a3-dab5-12992bc9dca2",
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   "outputs": [],
   "source": [
    "import glob\n",
    "import pandas as pd\n",
    "\n",
    "metrics = pd.read_csv(sorted(glob.glob(\"./runs/*/reports/metrics.csv\"))[-1])\n",
    "\n",
    "print(f\"tritonRoute_violations  {metrics['tritonRoute_violations'][0]}\")\n",
    "print(f\"Short_violations        {metrics['Short_violations'][0]}\")\n",
    "print(f\"OffGrid_violations      {metrics['OffGrid_violations'][0]}\")\n",
    "print(f\"MinHole_violations      {metrics['MinHole_violations'][0]}\")\n",
    "print(f\"Other_violations        {metrics['Other_violations'][0]}\")\n",
    "print(f\"Magic_violations        {metrics['Magic_violations'][0]}\")\n",
    "print(f\"pin_antenna_violations  {metrics['pin_antenna_violations'][0]}\")\n",
    "print(f\"net_antenna_violations  {metrics['net_antenna_violations'][0]}\")\n",
    "print(f\"lvs_total_errors        {metrics['lvs_total_errors'][0]}\")\n",
    "print(f\"cvc_total_errors        {metrics['cvc_total_errors'][0]}\")\n",
    "print(f\"klayout_violations      {metrics['klayout_violations'][0]}\")"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# References\n",
    "Inspired from:\n",
    "“Silicon Notebooks.” CHIPS Alliance, Apr. 08, 2023. Accessed: Apr. 10, 2023. [Online]. Available: https://github.com/chipsalliance/silicon-notebooks/blob/b65134a43b01ae31423f7ee87110740b2257ac42/digital-inverter-openlane.ipynb (Apache License 2.0)"
   ]
  }
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