@keiser/echip-webusb

Keiser Air eChip WebUSB Library

Project

This library handles communication with the Chip USB reader using WebUSB.

Required Hardware: USB to 1-Wire/iButton Adapter (DS9490)

Required Drivers: 1-Wire/iButton Drivers for Windows

Installation

Install with npm: npm install @keiser/echip-webusb

Usage

Import singleton instance from module using preferred module loading technique.

import ChipReaderWatcher from '@keiser/echip-webusb'

The ChipReaderWatcher handles permissions and USB connection events. On first load, the browser will not have provided a grant to the site to access the USB device, so the ChipReaderWatcher.start() method must be called by an event that originates from a user action. This may only be required once on the first visit to the site, or it may be required each time the site is loaded based on browser vendors preferred implementation.

connectButton.addEventListener('click', async () => {
  try {
    await ChipReaderWatcher.start()
  } catch (error) {
    console.error(error.message)
  }
})

Once the ChipReaderWatcher.start() method has been called the class will prompt the browser for permission and begin watching for devices matching the Chip Readers device signature. To be alerted when a device is found, pass a function to the ChipReaderWatcher.onConnect() method.

ChipReaderWatcher.onConnect((chipReader) => {
  console.log('Chip Reader Connected 😄')
})

The ChipReaderWatcher.onConnect() will pass in a ChipReader object which is the object bound to the physical device connected. This library is capable of handling multiple Chip Reader devices simultaneously, so the onConnect() method has potential for returning multiple ChipReader devices over the course of the application's life.

chipReader.onDisconnect(() => {
  console.log('Chip Reader Disconnected 😞')
})

The ChipReader object has an onDisconnect() method which will alert when the Chip Reader has been disconnected for some reason. Once a ChipReader object has been disconnected, it is disposed and cannot be used again. The next time the device is connected, a new ChipReader object will be returned.

chipReader.onChipDetect(async (chip) => {
  console.log('Chip Connected: ' + chip.id)
  if (chip instanceof DataChip) {
    chip.onData(data => console.log(data))
  }
})

The ChipReader object also has an onChipDetect() method which will alert when a valid chip has been placed into the reader. The event passes in a Chip object that can be used to interact with the chip data directly. Just like the ChipReaderWatcher.onConnect() method, the ChipReader.onChipDetect() method can be called multiple times for multiple chips all being handled concurrently. Once a chip is disconnected, the Chip object is disposed and cannot be reused.

Full example usage:

import ChipReaderWatcher, { DataChip } from '@keiser/echip-webusb'

document.addEventListener('DOMContentLoaded', event => {
  const connectButton = document.querySelector('#connect') as HTMLInputElement

  if (connectButton) {
    connectButton.addEventListener('click', async () => {
      try {
        await ChipReaderWatcher.start()
      } catch (error) {
        console.error(error.message)
      }
    })
  }

  ChipReaderWatcher.onConnect((chipReader) => {
    console.log('Chip Reader Connected 😄')

    chipReader.onChipDetect(async (chip) => {
      console.log('Chip Connected: ' + chip.id)
      if (chip instanceof DataChip) {
        chip.onData(data => console.log(data))
      }
    })

    chipReader.onDisconnect(() => {
      console.log('Chip Reader Disconnected 😞')
    })
  })
})

API

ChipReaderWatcher

The ChipReaderWatcher is a singleton class which handles the USB device monitoring and permissions handling. There can be only one ChipReaderWatcher instance created within a window scope, so the library instantiates the class during import and preserves a single instance for all imports.

Methods

Name	Usage
onConnect(Listener<ChipReader>): Disposable	Adds an event listener for when a Chip Reader device is connected. Callback method will be passed the new ChipReader instance for the connected device.
start(): Promise<void>	Initializes the watcher by first requesting permissions and then doing a hardware search. This method must be triggered by a user action such as a click event or the permission request will be denied.
stop(): Promise<void>	Closes all active connections.

ChipReader

The ChipReader instance is passed into the onConnect callback function and is the interface to the connected Chip Reader device.

Properties

Name	Usage
claimed: Promise<boolean>	Promise indicating if the USB device interface has been claimed.
disposed: boolean	Indicates if the device connection has been severed and the class instance disposed.

Methods

Name	Usage
onChipDetect(Listener<Chip>): Disposable	Adds an event listener for when a chip is connected to the Chip Reader device. Callback method will be passed the new Chip instance for the connected chip.
onDisconnect(Listener<null>): Disposable	Adds an event listener for when this Chip Reader device becomes disconnected. The instance will be disposed following this event.

BaseChip

The BaseChip instance is passed into the onChipDetect callback function and is the interface to the connected chip device. There are several different extensions to the base BaseChip object that can identified by doing a instanceOf check or looking at the type property.

Properties

Name	Usage
disposed: boolean	Indicates if the eChip connection has been severed and the class instance disposed.
data: ChipObject	Generic object with the current data from the chip.
id: string	UUID string of the eChip.
type: ChipType	ChipType enum value corresponding to the type of chip.

Methods

Name	Usage
destroy(): void	Called to disconnect the eChip device.
onDisconnect(Listener<null>): Disposable	Adds an event listener for when this chip becomes disconnected. The instance will be disposed following this event.
onData(Listener<ChipObject>): Disposable	Adds an event listener for when the chip data has changed.

TZChip and RTCChip

The TZChip and RTCChip are class extensions on the BaseChip class. They add no additional properties or methods, but allow the identification of chip type and will perform chip set operations automatically when detected. An event issued on the onData event indicates that the chips data has been successfully updated.

DataChip

The DataChip class extension on the BaseChip class adds additional properties and methods specific to the data chip.

Methods

Name	Usage
clearData(): Promise<void>	Method clears the data on the chip and resolve the promise on successful write. An onData event will be issues for the blank chip data.
setData({string: MachineObject}): Promise<void>	Method sets the data on the chip according to the data passed into the method. The method accepts an object with string keys corresponding to the machine's 4-digit model number with the MachineObject as the value of the property. Method resolve the promise on successful write. An onData event will be issues for the freshly written chip data.

Data Structures

ChipObject

interface ChipObject {
  type: ChipType
}

DataChipObject

interface DataChipObject {
  type: ChipType
  machineData: {[index: string]: MachineObject}
  rawData: Uint8Array[]
  validStructure: boolean
}

MachineObject

interface MachineObject {
  position: MachinePosition
  sets: MachineSet[]
}

MachinePosition

interface MachinePosition {
  chest: number | null
  rom2: number | null
  rom1: number | null
  seat: number | null
}

MachineSet

interface MachineSet {
  version: string
  serial: string
  time: string
  resistance: number
  precision: Precision
  units: ForceUnit
  repetitions: number
  peak: number | null
  work: number | null
  distance: number | null
  chest: number | null
  rom2: number | null
  rom1: number | null
  seat: number | null
  test: MachineTest | null
}

MachineTest

interface MachineTest {
  type: TestType
  high: MachineTestResult | null
  low: MachineTestResult | null
}

MachineTestResult

interface MachineTestResult {
  power: number
  velocity: number
  force: number
  position: number
}

Constants

enum Precision {
  dec = 'dec',
  int = 'int'
 }

enum ForceUnit {
  lb = 'lb',
  kg = 'kg',
  ne = 'ne',
  er = 'er'
}

enum TestType {
  power6r = 'power6r',
  a4206r = 'a4206r',
  a42010r = 'a42010r'
}

enum ChipType {
  dataChip = 12,
  rtcChip = 36,
  tzChip = 45,
  unknown = 0
}

References

Maxim Integrated 1-Wire USB Android notes

Maxim Integrated 1-Wire USB Android project

Copyright and License

Copyright Keiser Corporation under the MIT license.