{
  "metadata": {
    "id": "BM04B-SRSS-TB",
    "name": "JST BM04B-SRSS-TB 4-Pin 1 mm Header",
    "type": "connector",
    "description": "4-position 1.0 mm pitch surface-mount JST SR series top-entry board header. Used as a compact signal expansion port; the mating cable is JST's SHR-04V (1.0 mm pitch) crimped housing with discrete wires.",
    "manufacturer": "JST Sales America Inc.",
    "part_number": "BM04B-SRSS-TB",
    "datasheet_url": "https://www.digikey.com/en/products/detail/jst-sales-america-inc/BM04B-SRSS-TB/926696",
    "tags": [
      "jst",
      "bm04b-srss-tb",
      "sh",
      "sr",
      "4-pin",
      "1mm",
      "connector",
      "i2c",
      "uart"
    ],
    "schema_version": "1.4.0",
    "version": "1.0",
    "taxonomy": [
      "connector.signal_connector"
    ],
    "thumbnail": "https://storage.googleapis.com/protoboard-delta.firebasestorage.app/protoparts/jst-bm04b-srss-tb/thumbnail.png"
  },
  "domains": [
    {
      "domain": "electrical",
      "power_domains": [
        {
          "id": "signal",
          "name": "Expansion signal/power",
          "nominal_voltage_V": 3.3,
          "voltage_range_V": [
            0,
            5
          ],
          "max_current_mA": 1000,
          "isolation_type": "non_isolated",
          "ground_reference": "common",
          "description": "Expansion connector signal and power contacts."
        }
      ],
      "resources": [
        {
          "id": "pin1",
          "name": "Pin 1 input/output",
          "description": "Configurable expansion pin.",
          "functions": [
            {
              "name": "Pin 1",
              "direction": "bidirectional",
              "signal_class": "data"
            }
          ],
          "connector_type": "connector_pin",
          "power_domain_id": "signal"
        },
        {
          "id": "pin2",
          "name": "Pin 2 input/output",
          "description": "Configurable expansion pin.",
          "functions": [
            {
              "name": "Pin 2",
              "direction": "bidirectional",
              "signal_class": "data"
            }
          ],
          "connector_type": "connector_pin",
          "power_domain_id": "signal"
        },
        {
          "id": "pin3",
          "name": "Pin 3 input/output",
          "description": "Configurable expansion pin.",
          "functions": [
            {
              "name": "Pin 3",
              "direction": "bidirectional",
              "signal_class": "data"
            }
          ],
          "connector_type": "connector_pin",
          "power_domain_id": "signal"
        },
        {
          "id": "pin4",
          "name": "Pin 4 input/output",
          "description": "Configurable expansion pin.",
          "functions": [
            {
              "name": "Pin 4",
              "direction": "bidirectional",
              "signal_class": "data"
            }
          ],
          "connector_type": "connector_pin",
          "power_domain_id": "signal"
        }
      ],
      "interfaces": [
        {
          "id": "BM04B-SRSS-TB-connector",
          "name": "BM04B-SRSS-TB Connector",
          "protocol": {
            "type": "connector",
            "role": "peer"
          },
          "requires": [
            {
              "function": "Pin 1",
              "count": 1
            },
            {
              "function": "Pin 2",
              "count": 1
            },
            {
              "function": "Pin 3",
              "count": 1
            },
            {
              "function": "Pin 4",
              "count": 1
            }
          ],
          "constraints": {
            "max_connections": 1
          },
          "description": "Expansion connector. Mutually exclusive with the UART role on the same physical pins."
        }
      ],
      "supply_voltage_V": [
        0,
        5
      ],
      "pin_count": 4,
      "metadata": {
        "pitch_mm": 1,
        "series": "JST SH/SR"
      }
    },
    {
      "domain": "mechanical",
      "resources": [],
      "interfaces": [],
      "package_type": "4-position SMT header",
      "metadata": {
        "mounting_method": "surface_mount"
      }
    },
    {
      "domain": "thermal",
      "resources": [],
      "interfaces": [],
      "operating_temperature_C": [
        -40,
        85
      ],
      "metadata": {
        "requires_thermal_management": false
      }
    }
  ],
  "design_rules": [
    "Match the cable wire-color-to-pin convention to the module on the other end (e.g. M5Stack Grove cables use red=VCC, black=GND, white=SDA, yellow=SCL or similar conventions per vendor).",
    "Add ESD protection (a small TVS or RC network) close to the connector when the cable run leaves the enclosure.",
    "Provide strain relief to the connector body; the SR series cable retention is mechanical only and has no positive-locking latch.",
    "Pin 1 is the keyed-end side of the SR connector; verify the on-board polarity matches the cable's keying before reflow."
  ],
  "usage_notes": "Use as a compact signal/power expansion port. Pins 2 and 3 are multi-purpose - either an I2C pair, a UART pair, or two generic GPIOs - the board template selects which role at routing time. Pin 1 is the power output to the cabled module and pin 4 is the return ground. Mate to JST SHR-04V crimped cable assemblies; the SR series is unrelated to the SH series despite similar pitch.",
  "warnings": [
    "I2C and UART roles on pins 2/3 are mutually exclusive. The board template must commit to one before generating harnesses; mixed-role wiring will short the SCL line to UART_TX.",
    "1.0 mm pitch contacts are easy to short with whisker debris during reflow - inspect under magnification before first power-up.",
    "Some clone-grade SR-pitch crimped housings do not engage the JST locking detent, so cables can back out under vibration; use genuine JST cables for production builds."
  ],
  "artifacts": [
    {
      "type": "datasheet",
      "filePath": "artifacts/documentation/datasheet-url.txt",
      "url": "https://www.jst-connector.com/datasheet/jst-connector/BM02B-SRSS-TB.pdf",
      "fetched_at": "2026-05-05T04:43:42Z"
    }
  ],
  "purchaseInfo": [
    {
      "vendor": "JST",
      "link": "https://www.jst.com/series/headers-pcb-connectors/sr/",
      "isAffiliate": false,
      "vendorPartId": "BM04B-SRSS-TB",
      "title": "4-position SR series 1.0 mm pitch top-entry SMT header",
      "currentPriceUSD": "0.85",
      "packQuantity": 1,
      "minimumOrderQuantity": 1,
      "availabilityStatus": "unknown",
      "priceTimestamp": "2026-05-05T19:36:58.122Z",
      "currency": "USD",
      "productStatus": "active",
      "notes": "Manufacturer family page; mating cable housing is SHR-04V."
    },
    {
      "vendor": "DigiKey",
      "link": "https://www.digikey.com/en/products/result?keywords=BM04B-SRSS-TB",
      "isAffiliate": false,
      "vendorPartId": "455-BM04B-SRSS-TB-ND",
      "title": "CONN HEADER SMD 4POS 1MM",
      "currentPriceUSD": "1.15",
      "packQuantity": 1,
      "minimumOrderQuantity": 1,
      "availabilityStatus": "unknown",
      "priceTimestamp": "2026-05-05T19:36:58.122Z",
      "currency": "USD",
      "productStatus": "active",
      "notes": "Cut tape. Order matching SHR-04V housing + crimped contacts separately for cable assemblies."
    }
  ]
}