{
  "node": {
    "id": "term:i2c",
    "type": "Term",
    "label": "I²C",
    "properties": {
      "id": "i2c",
      "name": "I²C",
      "aka": [
        "I2C",
        "IIC",
        "inter-integrated circuit",
        "TWI",
        "two-wire interface"
      ],
      "section": "topic-data",
      "definition": "A two-wire serial bus — one clock line and one data line, both pulled up — on which a controller addresses many small chips at 100 kbit/s, 400 kbit/s or faster. Inside a battery pack it links the fuel gauge, protection chip, memory and temperature sensors; SMBus is derived from it with tighter timing rules.",
      "related": [
        "smbus",
        "fuel-gauge",
        "afe",
        "mcu",
        "gpio",
        "pmbus"
      ],
      "url": "https://lemonergy.com/learn/glossary/i2c/",
      "mentions": []
    }
  },
  "edges": [
    {
      "id": "edge:belongsTo/term:i2c/topic:topic-data",
      "source": "term:i2c",
      "target": "topic:topic-data",
      "type": "belongsTo",
      "properties": {
        "sourceFile": "terms.json"
      }
    },
    {
      "id": "edge:relatedTo/term:i2c/term:smbus",
      "source": "term:i2c",
      "target": "term:smbus",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    },
    {
      "id": "edge:relatedTo/term:i2c/term:fuel-gauge",
      "source": "term:i2c",
      "target": "term:fuel-gauge",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    },
    {
      "id": "edge:relatedTo/term:i2c/term:afe",
      "source": "term:i2c",
      "target": "term:afe",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    },
    {
      "id": "edge:relatedTo/term:i2c/term:mcu",
      "source": "term:i2c",
      "target": "term:mcu",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    },
    {
      "id": "edge:relatedTo/term:i2c/term:gpio",
      "source": "term:i2c",
      "target": "term:gpio",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    },
    {
      "id": "edge:relatedTo/term:i2c/term:pmbus",
      "source": "term:i2c",
      "target": "term:pmbus",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    }
  ],
  "neighbors": [
    {
      "id": "topic:topic-data",
      "type": "Topic",
      "label": "Data, communication and electronics",
      "properties": {
        "id": "topic-data",
        "name": "Data, communication and electronics",
        "lede": "The control units, chips, protocols and file formats through which a battery is measured, controlled and logged.",
        "context": "Separate quantities from encoding and transport.",
        "example": "2500 in a log might mean 25.00 °C, 2.5 V or raw counts. Units and scale must accompany the value.",
        "lesson_url": "https://lemonergy.com/learn/fundamentals/battery-basics/",
        "lesson_label": "Open battery basics"
      }
    },
    {
      "id": "term:smbus",
      "type": "Term",
      "label": "SMBus",
      "properties": {
        "id": "smbus",
        "name": "SMBus",
        "aka": [
          "System Management Bus"
        ],
        "section": "topic-pack",
        "definition": "The two-wire bus, derived from I²C, over which a laptop or tool battery reports its charge, health and limits to the host and charger. The Smart Battery Data specification defines the register set, so any compliant charger can read it.",
        "related": [
          "bms",
          "fuel-gauge",
          "consumer-electronics",
          "charger",
          "smart-battery-system",
          "i2c"
        ],
        "url": "https://lemonergy.com/learn/glossary/smbus/",
        "mentions": []
      }
    },
    {
      "id": "term:fuel-gauge",
      "type": "Term",
      "label": "Fuel gauge",
      "properties": {
        "id": "fuel-gauge",
        "name": "Fuel gauge",
        "aka": [
          "gas gauge"
        ],
        "section": "topic-pack",
        "definition": "The single chip in a phone, laptop or power tool that does the BMS’s state-estimation job for one or a few cells: coulomb counting corrected by an OCV model, with impedance tracking in better parts. It reports remaining capacity over SMBus or I²C.",
        "related": [
          "coulomb-counting",
          "state-of-charge",
          "smbus",
          "consumer-electronics",
          "afe",
          "soc-indicator"
        ],
        "url": "https://lemonergy.com/learn/glossary/fuel-gauge/",
        "mentions": [
          "coulomb",
          "impedance",
          "open-circuit-voltage",
          "bms"
        ]
      }
    },
    {
      "id": "term:afe",
      "type": "Term",
      "label": "Analog front end",
      "properties": {
        "id": "afe",
        "name": "Analog front end",
        "abbr": "AFE",
        "aka": [
          "cell monitoring IC",
          "battery monitor IC",
          "BMIC"
        ],
        "section": "topic-data",
        "definition": "The integrated circuit that measures a stack of series cells — typically 6 to 18 per chip — with millivolt accuracy, reads thermistors, switches balancing and talks to the controller over an isolated daisy chain. It is the part of a BMS that touches the cells, and its accuracy limits how well SOC can be known.",
        "related": [
          "cell-supervision-circuit",
          "isospi",
          "voltage-sense",
          "cell-balancing",
          "adc",
          "bmu"
        ],
        "url": "https://lemonergy.com/learn/glossary/afe/",
        "mentions": [
          "state-of-charge",
          "bms"
        ]
      }
    },
    {
      "id": "term:mcu",
      "type": "Term",
      "label": "Microcontroller",
      "properties": {
        "id": "mcu",
        "name": "Microcontroller",
        "abbr": "MCU",
        "section": "topic-data",
        "definition": "The processor that runs BMS firmware: state estimation, protection, balancing decisions and communication. Automotive BMS controllers use safety microcontrollers with lockstep cores and hardware self-tests so they can meet ASIL C or D.",
        "related": [
          "bmu",
          "firmware",
          "functional-safety",
          "fpga",
          "afe"
        ],
        "url": "https://lemonergy.com/learn/glossary/mcu/",
        "mentions": [
          "bms",
          "lockstep-core"
        ]
      }
    },
    {
      "id": "term:gpio",
      "type": "Term",
      "label": "GPIO",
      "properties": {
        "id": "gpio",
        "name": "GPIO",
        "aka": [
          "general-purpose input/output",
          "GPIO pin"
        ],
        "section": "topic-data",
        "definition": "A microcontroller pin that firmware can configure as a digital input or output for whatever the design needs. In a battery pack GPIOs drive LED gauges, read a button or presence contact, enable a charger or regulator and switch between battery banks, so one pack design can serve several products.",
        "related": [
          "mcu",
          "firmware",
          "soc-indicator",
          "i2c",
          "embedded-charger"
        ],
        "url": "https://lemonergy.com/learn/glossary/gpio/",
        "mentions": [
          "charger"
        ]
      }
    },
    {
      "id": "term:pmbus",
      "type": "Term",
      "label": "PMBus",
      "properties": {
        "id": "pmbus",
        "name": "PMBus",
        "aka": [
          "Power Management Bus"
        ],
        "section": "topic-data",
        "definition": "An open protocol, built on SMBus, for configuring and monitoring power converters through a standard command set — setting output voltage, reading current and temperature, logging faults. A battery pack with its own regulated output or charger stage can expose it, so the host controls the pack like any other power supply.",
        "related": [
          "smbus",
          "i2c",
          "power-path-management",
          "charger"
        ],
        "url": "https://lemonergy.com/learn/glossary/pmbus/",
        "mentions": []
      }
    }
  ]
}