MCP23S17 SPI GPIO Expander

{
  "schema_version": 1,
  "type": "component",
  "slug": "mcp23s17",
  "title": "MCP23S17 SPI GPIO Expander",
  "brief": "16-bit general-purpose I/O expander with an SPI interface and interrupt outputs.",
  "version": "0.1.0",
  "license": "CC-BY-SA-4.0",
  "tags": [
    "gpio-expander",
    "spi",
    "io-expander",
    "interrupt",
    "microchip",
    "soic-28"
  ],
  "component": {
    "mpn": "MCP23S17",
    "manufacturer": "Microchip",
    "package": "SOIC-28",
    "pin_count": 28,
    "category": "Interface",
    "subcategory": "I/O Expander",
    "datasheet": "https://ww1.microchip.com/downloads/en/DeviceDoc/20001952C.pdf",
    "parts": {
      "symbol": "mcp23s17.kicad_sym",
      "footprint": "mcp23s17.kicad_mod",
      "model_3d": "mcp23s17-etched.glb",
      "model_3d_plain": "mcp23s17.glb",
      "lbr": "mcp23s17.lbr",
      "model_3d_step": "mcp23s17-etched.step",
      "model_3d_step_plain": "mcp23s17.step"
    },
    "distributor_links": {},
    "pins": [
      {
        "number": "1",
        "name": "GPB0",
        "type": "bidirectional",
        "description": "PORTB bit 0 bidirectional I/O. Can be enabled for interrupt-on-change and/or internal weak pull-up. Defaults to input at power-up. Max sink/source 25 mA per pin."
      },
      {
        "number": "2",
        "name": "GPB1",
        "type": "bidirectional",
        "description": "PORTB bit 1 bidirectional I/O. Can be enabled for interrupt-on-change and/or internal weak pull-up. Defaults to input at power-up."
      },
      {
        "number": "3",
        "name": "GPB2",
        "type": "bidirectional",
        "description": "PORTB bit 2 bidirectional I/O. Can be enabled for interrupt-on-change and/or internal weak pull-up. Defaults to input at power-up."
      },
      {
        "number": "4",
        "name": "GPB3",
        "type": "bidirectional",
        "description": "PORTB bit 3 bidirectional I/O. Can be enabled for interrupt-on-change and/or internal weak pull-up. Defaults to input at power-up."
      },
      {
        "number": "5",
        "name": "GPB4",
        "type": "bidirectional",
        "description": "PORTB bit 4 bidirectional I/O. Can be enabled for interrupt-on-change and/or internal weak pull-up. Defaults to input at power-up."
      },
      {
        "number": "6",
        "name": "GPB5",
        "type": "bidirectional",
        "description": "PORTB bit 5 bidirectional I/O. Can be enabled for interrupt-on-change and/or internal weak pull-up. Defaults to input at power-up."
      },
      {
        "number": "7",
        "name": "GPB6",
        "type": "bidirectional",
        "description": "PORTB bit 6 bidirectional I/O. Can be enabled for interrupt-on-change and/or internal weak pull-up. Defaults to input at power-up."
      },
      {
        "number": "8",
        "name": "GPB7",
        "type": "bidirectional",
        "description": "PORTB bit 7 bidirectional I/O. Can be enabled for interrupt-on-change and/or internal weak pull-up. Defaults to input at power-up."
      },
      {
        "number": "9",
        "name": "VDD",
        "type": "power_in",
        "description": "Positive supply. Operating range 1.8 V to 5.5 V (-40 to +85 C), 2.7 V to 5.5 V (-40 to +85 C), or 4.5 V to 5.5 V (-40 to +125 C). Decouple to VSS with a local bypass capacitor."
      },
      {
        "number": "10",
        "name": "VSS",
        "type": "power_in",
        "description": "Ground reference. Return for all device currents; connect to system ground plane."
      },
      {
        "number": "11",
        "name": "CS",
        "type": "input",
        "description": "SPI chip select input (active-low). Frames each SPI transaction; must be driven low to enable serial communication with this device."
      },
      {
        "number": "12",
        "name": "SCK",
        "type": "input",
        "description": "SPI serial clock input. Maximum 10 MHz. Clocks data into SI on the master-configured edge and out on SO."
      },
      {
        "number": "13",
        "name": "SI",
        "type": "input",
        "description": "SPI serial data input (MOSI). Receives command, address and write-data bytes from the SPI master."
      },
      {
        "number": "14",
        "name": "SO",
        "type": "output",
        "description": "SPI serial data output (MISO). Drives read-data back to the SPI master; high-impedance while CS is high."
      },
      {
        "number": "15",
        "name": "A0",
        "type": "input",
        "description": "Hardware address bit 0. Sets the least-significant bit of the 3-bit chip address matched during SPI transactions. Must be externally biased (tied to VDD or VSS); do not leave floating."
      },
      {
        "number": "16",
        "name": "A1",
        "type": "input",
        "description": "Hardware address bit 1. Must be externally biased (tied to VDD or VSS)."
      },
      {
        "number": "17",
        "name": "A2",
        "type": "input",
        "description": "Hardware address bit 2. Must be externally biased (tied to VDD or VSS). Combined with A0/A1 allows up to eight MCP23S17 devices to share one SPI bus."
      },
      {
        "number": "18",
        "name": "RESET",
        "type": "input",
        "description": "Active-low hardware reset input. Forces all registers to their POR defaults while asserted. Must be externally biased (tie to VDD through a pull-up if unused); do not leave floating."
      },
      {
        "number": "19",
        "name": "INTB",
        "type": "output",
        "description": "Interrupt output for PORTB. Polarity and drive configurable as active-high, active-low, or open-drain via IOCON.INTPOL/ODR. Can be OR'd with INTA when IOCON.MIRROR = 1."
      },
      {
        "number": "20",
        "name": "INTA",
        "type": "output",
        "description": "Interrupt output for PORTA. Polarity and drive configurable as active-high, active-low, or open-drain via IOCON.INTPOL/ODR. Can be OR'd with INTB when IOCON.MIRROR = 1."
      },
      {
        "number": "21",
        "name": "GPA0",
        "type": "bidirectional",
        "description": "PORTA bit 0 bidirectional I/O. Can be enabled for interrupt-on-change and/or internal weak pull-up. Defaults to input at power-up."
      },
      {
        "number": "22",
        "name": "GPA1",
        "type": "bidirectional",
        "description": "PORTA bit 1 bidirectional I/O. Can be enabled for interrupt-on-change and/or internal weak pull-up. Defaults to input at power-up."
      },
      {
        "number": "23",
        "name": "GPA2",
        "type": "bidirectional",
        "description": "PORTA bit 2 bidirectional I/O. Can be enabled for interrupt-on-change and/or internal weak pull-up. Defaults to input at power-up."
      },
      {
        "number": "24",
        "name": "GPA3",
        "type": "bidirectional",
        "description": "PORTA bit 3 bidirectional I/O. Can be enabled for interrupt-on-change and/or internal weak pull-up. Defaults to input at power-up."
      },
      {
        "number": "25",
        "name": "GPA4",
        "type": "bidirectional",
        "description": "PORTA bit 4 bidirectional I/O. Can be enabled for interrupt-on-change and/or internal weak pull-up. Defaults to input at power-up."
      },
      {
        "number": "26",
        "name": "GPA5",
        "type": "bidirectional",
        "description": "PORTA bit 5 bidirectional I/O. Can be enabled for interrupt-on-change and/or internal weak pull-up. Defaults to input at power-up."
      },
      {
        "number": "27",
        "name": "GPA6",
        "type": "bidirectional",
        "description": "PORTA bit 6 bidirectional I/O. Can be enabled for interrupt-on-change and/or internal weak pull-up. Defaults to input at power-up."
      },
      {
        "number": "28",
        "name": "GPA7",
        "type": "bidirectional",
        "description": "PORTA bit 7 bidirectional I/O. Can be enabled for interrupt-on-change and/or internal weak pull-up. Defaults to input at power-up."
      }
    ],
    "provenance": {
      "extractor": "ds2sf",
      "datasheet": {
        "url": "https://ww1.microchip.com/downloads/en/DeviceDoc/20001952C.pdf",
        "pages": 42,
        "sha256": "14159c6f5655e943",
        "source_tier": "mfr"
      },
      "cad": "KiCad official (CC-BY-SA 4.0)",
      "pins": {
        "total": 28,
        "described": 28,
        "cites_pages": true,
        "refuses_to_fabricate": true
      }
    },
    "viewers": {
      "symbol": "viewers/symbol.html",
      "footprint": "viewers/footprint.html"
    },
    "models_3d": [
      {
        "file": "mcp23s17.step",
        "role": "plain",
        "up": "Z",
        "units": "mm",
        "origin": "footprint origin = pad-pattern centre",
        "seat": "z = 0",
        "extents_mm": [
          10.3,
          17.9,
          2.75
        ],
        "zmin_mm": 0,
        "centre_offset_mm": 0,
        "footprint_binding": "identity",
        "sha256": "b889a13dbe9ec59e79fa9f1b5118b00bfa54f9582392335ff3365b64afc264b1",
        "checked": "2026-10-07",
        "checked_by": "factory/step_pose.py (Z-up, origin, seat, binding)"
      },
      {
        "file": "mcp23s17-etched.step",
        "role": "eda",
        "up": "Z",
        "units": "mm",
        "origin": "footprint origin = pad-pattern centre",
        "seat": "z = 0",
        "extents_mm": [
          10.3,
          17.9,
          2.75
        ],
        "zmin_mm": 0,
        "centre_offset_mm": 0,
        "footprint_binding": "identity",
        "sha256": "11383e07d04533f5a48ded829719caa2be467ad0298454760b99ecf753f2fc28",
        "checked": "2026-10-07",
        "checked_by": "factory/step_pose.py (Z-up, origin, seat, binding)"
      }
    ]
  },
  "metadata": {
    "specs": {
      "Type": "16-bit I/O expander",
      "Interface": "SPI (up to 10 MHz)",
      "I/O": "16, two 8-bit ports (GPA/GPB)",
      "Per-pin features": "Direction, pull-up, polarity, interrupt-on-change",
      "Addressing": "3 hardware address pins (up to 8 on a bus)",
      "Supply voltage": "1.8 V to 5.5 V",
      "Operating temperature": "-40 C to 85 C"
    }
  },
  "sections": [
    "hero",
    "viewers",
    "readme",
    "breadcrumbs",
    "info"
  ],
  "discovery_triggers": [
    "SPI GPIO expander",
    "add more I/O",
    "port expander",
    "16-bit I/O over SPI"
  ],
  "discovery_pitch": "Add 16 interrupt-capable GPIOs to an MCU over SPI, with up to 8 devices on one bus via hardware address pins.",
  "author": {
    "name": "Ray"
  },
  "dependencies": {},
  "hero": {
    "type": "image",
    "path": "docs/hero.png"
  },
  "files": [
    "page.json",
    "README.md",
    "mcp23s17.kicad_sym",
    "mcp23s17.kicad_mod",
    "mcp23s17.glb",
    "mcp23s17.lbr",
    "docs/hero.png",
    "docs/mcp23s17-datasheet.pdf",
    "viewers/symbol.html",
    "viewers/footprint.html",
    "mcp23s17-etched.step"
  ],
  "variants": [
    {
      "mpn": "MCP23S17SP",
      "kind": "unknown"
    },
    {
      "mpn": "MCP23S17E/SP",
      "kind": "unknown"
    },
    {
      "mpn": "MCP23S17SO",
      "kind": "unknown"
    },
    {
      "mpn": "MCP23S17E/SO",
      "kind": "unknown"
    },
    {
      "mpn": "MCP23S17T-E/SO",
      "kind": "unknown"
    },
    {
      "mpn": "MCP23S17SS",
      "kind": "unknown"
    },
    {
      "mpn": "MCP23S17E/SS",
      "kind": "unknown"
    },
    {
      "mpn": "MCP23S17T-E/SS",
      "kind": "unknown"
    },
    {
      "mpn": "MCP23S17ML",
      "kind": "unknown"
    },
    {
      "mpn": "MCP23S17E/ML",
      "kind": "unknown"
    },
    {
      "mpn": "MCP23S17T-E/ML",
      "kind": "unknown"
    }
  ]
}