Synopsis

NodeJS addon for simple usage of 1wire over I2C and DS2482-100/800 master. Multiple masters and overdrive speed is supported. Target OS is LINUX with I2C module loaded. Currently only tested on Rasberry PI. The following devices are supported:

• DS18S20
• DS18B20
• DS2408

Prerequisites

Kernel modules

On Rasberry Pi the following steps load the required modules:

• Comment out i2c-dev and i2c-bcm2708 inside /etc/modprobe.d/raspi-blacklist.conf
• Add to /etc/modules i2c-dev
• Add to /etc/modules i2c-bcm2708
• Reboot your system

Check if your masters can be found

Using i2cdetect, the addresses of all DS2482 should be shown:

• i2cdetect -y 0
• i2cdetect -y 1

Install the package

Because the package is written in C++, it has to be compiled first. This requires to install:

• node-gyp (npm install -g node-gyp)
• python (v2.7 recommended)
• make
• GCC

Then just execute:

npm install w1direct

Register your masters

You can register 1..n masters using the registerDS2482Master function:

var w1direct = require('w1direct');

w1 = new w1direct.Manager();
w1.registerDS2482Master({
	name	  : 'MASTER1',      // Any name for later master access
	subType   : '100',          // 100 or 800 for ds2482-100/800
	devFile	  : '/dev/i2c-1',   // The I2C device file
	address	  : 0x18            // The I2C master address (shown in i2cdetect)
});

Search devices

Just execute:

w1.syncAllDevices();

This starts a new search on all registered masters for devices and returns an object like shown below. If you execute the search again, all devices will return inside the updated key. If a device is removed, it will be shown once inside the removed key.

{ added:
   [{ id	   : '104C3D7101080061', //DS18S20
      state	   : 'ready',
      master   : 'MASTER1',
      bus	   : 0,
      crcError : false },
    { id       : '28E445AA040000FC', //DS18B20
      state	   : 'ready',
      master   : 'MASTER1',
      bus      : 0,
      crcError : false },
    { id       : '29AD5712000000CE', //DS2408
      state    : 'ready',
      master   : 'MASTER1',
      bus      : 0,
      crcError : false }],
  updated: [],
  removed: [] }

Searching all masters/buses can be a long action. For a faster search, you can use one of the following functions:

w1.syncMasterDevices({masterName:'MASTER1'})  			//Search on MASTER1 all buses
w1.syncBusDevices({masterName:'MASTER1', busNumber:0})  //Search on MASTER1 bus 0

Read devices

There are two possible types. The first is called values, which holds values e.g. temperature. The second type is called properties, which shows internal device properties. Reading both types needs more time. So normally you should only use the type you need.

Moreover, you can define multiple devices for read. Internally, this is performance optimized. So standard speed devices are read first. Afterwards the bus is switched to overdrive speed and all other devices are read.

w1.readDevicesById({
   fields   :['values', 'properties'], 
   deviceIds:['104C3D7101080061', '28E445AA040000FC', '29AD5712000000CE']
)}

This returns:

{ 
  '104C3D7101080061': //DS18S20
   { ioSpeed	 : 'standard',
     resolution	 : '12bit',
     powerSupply : true,
     tCelsius	 : '85.0',
     crcError	 : false },
  '28E445AA040000FC': //DS18B20
   { ioSpeed	 : 'standard',
     resolution	 : '12bit',
     powerSupply : true,
     tCelsius	 : '85.0',
     crcError	 : false },
  '29AD5712000000CE': //DS2408
   { ioSpeed	 : 'standard',
     rstzPinMode : 'resetInput',
     powerSupply : true,
     pioInput	 : { hex: '0x1f', decimal: 31,  binary: '00011111' },
     pioOutput	 : { hex: '0xff', decimal: 255, binary: '11111111' },
     pioActivity : { hex: '0x00', decimal: 0,   binary: '00000000' },
     crcError	 : false }
}

Broadcast devices

In the result above, the temperature is "85.0". This is quite hot :-) To read the right temperature, each device has to calculate the temperature first. To start this calculation, a "broadcast" command can be send:

w1.broadcastBusCommand({
	masterName : 'MASTER1', 
	busNumber  : 0, 
	command    : "convertTemperature"
})     

After the command is send, all devices on the specified Master/Bus start to build a memory entry with the current temperature. After a delay, the correct temperature can be read. The delays are different for each device and resolution. Details are shown below in the device section.

Update devices

For each device, there are some possible updates. Details are shown below in the device section.

w1.updateDeviceById({deviceId:'DEVICEID', set:'KEY', value:'VALUE'})

DS18S20 and DS18B20

Read returns

{ 
  ioSpeed	  : 'standard', //property
  resolution  : '12bit',    //property
  powerSupply : true,       //property
  tCelsius	  : '85.0'  	 //value   
}

Update options

w1.updateDeviceById({deviceId:'DEVICEID', set:'resolution', value:'9bit'})
w1.updateDeviceById({deviceId:'DEVICEID', set:'resolution', value:'10bit'})
w1.updateDeviceById({deviceId:'DEVICEID', set:'resolution', value:'11bit'})
w1.updateDeviceById({deviceId:'DEVICEID', set:'resolution', value:'12bit'})

A higher resolution will return you more decimal values. For the DS18S20 the decimals are interpolated. The possible decimals are:

{
  "9bit":  [0,                                                     0.5                                                    ],
  "10bit": [0,                        0.25,                        0.5,                        0.75                       ],
  "11bit": [0,         0.125,         0.25,         0.375,         0.5,         0.625,         0.75,         0.875        ],
  "12bit": [0, 0.0625, 0.125, 0.1875, 0.25, 0.3125, 0.375, 0.4375, 0.5, 0.5625, 0.625, 0.6875, 0.75, 0.8125, 0.875, 0.9375]
}

The calculation delays are:

{		  //DS18S20, DS18B20
  "9bit":  [750ms,   94ms],
  "10bit": [750ms,   188ms],
  "11bit": [750ms,   375ms],
  "12bit": [750ms,   750ms]
}

DS2408

Read returns

{ 	
	ioSpeed     : 'standard',   //property
    rstzPinMode : 'resetInput', //property
    powerSupply : true,         //property  
    pioInput    : { hex: '0x1f', decimal: 31,  binary: '00011111' },  //value
    pioOutput   : { hex: '0xff', decimal: 255, binary: '11111111' },  //value
    pioActivity : { hex: '0x00', decimal: 0,   binary: '00000000' }   //value
}

Update options

//Communication speed
w1.updateDeviceById({deviceId:'DEVICEID', set:'ioSpeed', value:'standard'})
w1.updateDeviceById({deviceId:'DEVICEID', set:'ioSpeed', value:'overdrive'})

//The RSTZ pin can be RESET input or STROBE output
w1.updateDeviceById({deviceId:'DEVICEID', set:'rstzPinMode', value:'strobeOutput'})
w1.updateDeviceById({deviceId:'DEVICEID', set:'rstzPinMode', value:'resetInput'})

//Sets the PIO output to 0xff and 0xbb
w1.updateDeviceById({deviceId:'DEVICEID', set:'pioOutput', value:'0xff'})
w1.updateDeviceById({deviceId:'DEVICEID', set:'pioOutput', value:'0xbb'})

//Sets PIO Pin 0 to 1 and Pin 2 to 0
w1.updateDeviceById({deviceId:'DEVICEID', set:'pioOutputPort', value:'p0,1'})
w1.updateDeviceById({deviceId:'DEVICEID', set:'pioOutputPort', value:'p2,0'})

//Reset the activity latch
w1.updateDeviceById({deviceId:'DEVICEID', set:'pioActivity', value:'0x00'})

Examples

Read current temperature of DS18B20

var w1direct = require('w1direct');

w1 = new w1direct.Manager();

w1.registerDS2482Master({
   name      : 'MASTER1',
   subType   : '100',
   devFile   : '/dev/i2c-1',
   address   : 0x18
});

//search
w1.syncAllDevices()

//inital setup
w1.updateDeviceById({deviceId:"28E445AA040000FC", set:'resolution', value:'12bit'})

//broadcast
w1.broadcastBusCommand({masterName:'MASTER1', busNumber:0, command:"convertTemperature"})

//Read after 750ms in 12bit. During the 750ms other devices could be read. 
setTimeout(function() {
  result = w1.readDevicesById({fields:['values'], deviceIds:['28E445AA040000FC']})
  console.log(result)
}, 750);

Result:

{ '28E445AA040000FC': { tCelsius: '25.6875', crcError: false } }

Tests

This lib is fully tested using jasmine-node. Please have look into the "test" folder for more information.

License

MIT