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DS2482 Onewire Bridge

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Provides an interface for the Dallas DS2482 onewire bridge

Install

$ npm install ds2482

Usage

const DS2482 = require('ds2482');

const wire = new DS2482();

wire.init()
.then(() => wire.search())

.then(found => {
  console.log(found); // Returns a list of ROM addresses as hex encoded strings
})

.catch(err => {
  console.error(err);
});

API

new DS2482([options])

Creates an interface for a Dallas DS2482 i2c to onewire bridge chip

Options:

  • i2c an instance of i2c
  • address the i2c address of the bridge chip, default: 0x18
  • device the location of the i2c interface, default: /dev/i2c-1

wire.init() alias: wire.reset()

Resets the bridge chip and any onewire devices connected to it

Returns: Promise <Uint8> resolves with status register

wire.configureBridge([options])

Configures the onewire interface for subsequent communication

Options:

  • activePullup controls whether to use active or passive pullup
  • strongPullup enables strong pullup only after next command then resets
  • overdrive enable overdrive speed for the bridge chip

Returns: Promise <Uint8> resolves with configuration register

wire.selectChannel([channel])

Select the onewire channel to use for subsequent commands

Note: Only for use with DS2482-800

Arguments:

  • channel channel to select, defaults to 0

Returns: Promise <Uint8> resolves with channel selection register

wire.sendCommand(command [, rom])

Sends a command to a onewire device if specified or all onewire devices if omitted

Arguments:

  • command command to send as an unsigned integer
  • rom optional ROM address of the device to send the command to as a 16 character hex encoded string

Returns: Promise <Uint8> resolves with status register

wire.search()

Searches the bus for all onewire devices and returns a list of ROM addresses as hex encoded strings

Returns: Promise <String[]> resolves with list of roms

[
  "2826274402000012",
  "2889075f0200003e",
  "3ae9f412000000a6"
]

wire.searchByFamily(family)

Searches the bus for all onewire devices of a particular family and returns a list of ROM addresses as hex encoded strings

Arguments:

  • family the family to search as either an unsigned integer or 2 character hex encoded string

Returns: Promise <String[]> resolves with list of roms

[
  "2826274402000012",
  "2889075f0200003e"
]

wire.searchROM()

Searches the bus for the next onewire device and returns the ROM address as a hex encoded string

Returns: Promise <String> resolves with rom

"2826274402000012"

wire.readROM()

Reads the ROM address of the single onewire device and returns it as a hex encoded string

NOTE: Will return a CRC mismatch error if multiple devices are on the bus

Returns: Promise <String> resolves with rom

wire.matchROM(rom)

Selects a single onewire device to send a command to

Arguments:

  • rom the ROM address of the device to select as a 16 character hex encoded string

Returns: Promise <Uint8> resolves with status register

wire.skipROM()

Selects all onewire devices to send a command to

NOTE: Can only be used for commands that don't return a response

Returns: Promise <Uint8> resolves with status register

wire.writeData(data)

Writes one or more bytes to the onewire bus

Arguments:

  • data a single byte, array of bytes or data buffer to be written out

Returns: Promise <Uint8> resolves with status register

wire.readData(size)

Reads one or more bytes from the onewire bus and returns a data buffer

Arguments:

  • size number of bytes to be read in

Returns: Promise <Buffer> resolves with data buffer

DS2482.checkCRC(buffer)

Checks that the crc in the last byte matches the rest of the buffer

Arguments:

  • buffer the data buffer to be checked

Returns: Boolean