Hardware Contract

The hardware contract system bridges your typeCAD hardware design with firmware development. It exports a JSON manifest describing which MCU pins are connected to what, enabling automatic firmware code generation.

Overview

A hardware contract is a JSON file that describes:

Which MCU is being used
Which pins are connected and to what nets
Available peripherals (I2C, SPI, UART) auto-detected from KiCAD pin names

Usage

import { PCB, Component } from '@typecad/typecad';

let pcb = new PCB('my_board');

let mcu = new Component({
  symbol: 'MCU_Microchip_ATtiny:ATtiny3227-M',
  footprint: 'Package_DFN_QFN:QFN-20-1EP_4x4mm_P0.5mm',
  typehal: {
    boardPackage: 'ATtiny3227',
    driver: 'megaTinyCore',
    pinLookup: {
      1: 'PB5',
      2: 'PB3',
      5: 'PB0',
      // ...
    }
  }
});

pcb.net(mcu.pin(5), sensor.SDA);
pcb.net(mcu.pin(7), sensor.SCL);

// After create, export the contract
pcb.create(mcu, sensor);
pcb.contract({ mcuReference: mcu.reference });

Contract Output

{
  "version": 1,
  "mcu": {
    "symbol": "MCU_Microchip_ATtiny:ATtiny3227-M",
    "reference": "U1",
    "value": "",
    "footprint": "Package_DFN_QFN:QFN-20-1EP_4x4mm_P0.5mm",
    "mpn": "",
    "datasheet": "",
    "description": ""
  },
  "connectedPins": {
    "5": {
      "pinName": "PA0",
      "pinType": "bidirectional",
      "boardName": "PB0",
      "net": "SDA",
      "externalComponents": []
    },
    "7": {
      "pinName": "PA2",
      "pinType": "bidirectional",
      "boardName": "PB2",
      "net": "SCL",
      "externalComponents": []
    }
  },
  "availablePeripherals": {
    "i2c": true,
    "spi": false,
    "uart": false
  }
}

`typehal` Property

The typehal property on Component provides the metadata needed for contract generation:

Field	Description
`boardPackage`	MCU package identifier for firmware tools
`driver`	Firmware framework/driver name
`role`	Component role in the design
`config`	Additional configuration for the firmware
`pinLookup`	Mapping from IC pin numbers to board framework pin names

Peripheral Detection

typeCAD automatically detects available peripherals by analyzing KiCAD pin names. If a component has pins named SDA and SCL, I2C is detected. Pins named MOSI, MISO, SCK, and CS indicate SPI. RX and TX pins indicate UART.

TypeHAL Integration

The hardware contract is designed to work with TypeHAL, a firmware generation tool that can take the contract JSON and produce initialization code for your MCU. This enables a seamless flow from hardware design to firmware development.

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