README

cd-sigfox-parser

Sigfox and LoRa data parser used by https://ebeewan.com.

Based on sigfox-parser from Waylay

Usage

Parse a message

require('sigfox-parser')(<messagebytes>, <formatstring>, [<conditionstring>]);

messagebytes: The bytes of the message encoded in a hexadecimal String.

formatstring: A formatstring according to the Sigfox documentation.

conditionstring: A formatstring according to the Sigfox documentation.

Example

const parser = require('cd-sigfox-parser');

let parsed = parser('C01234','b1::bool:7 b2::bool:6 i1:1:uint:16');

// Conditions, b1 and b2 are present but not i1
parsed = parser('06C0','status::uint:8 b1::bool:7 b2::bool:6 i1:1:uint:16', 'b1:0:bool:2 b2:0:bool:1 i1:0:bool:0');

// Conditions, i1 and i3 are present but not i2
parsed = parser('0512341234','status::uint:8 i1::uint:16 i2::uint:16 i3:1:uint:16', 'i1:0:bool:2 i2:0:bool:1 i3:0:bool:0');

// Conditions, if the first byte is not equale to 15 the parser return null
parsed = parser('0512341234','status::uint:8 i1::uint:16 i2::uint:16 i3:1:uint:16', 'message::uint:8::15');
/**
  {
    status: 5,
    i1: 4660,
    i3: 4660
  }
**/

*In the first example about conditions, I put an offset because for the byte 0 without offset the parser never found it.

The variable parsed now contains:

{
  b1: true,
  b2: true,
  i1: 0x1234
}

New HEX condition

Now you can parse message with conditionnal hex value to defined field included in payload.

E.g : Temperature is preceded by 0x01 and humidity by 0x02


// simple example
parsed = parser('0100e20229','temperature::uint:16 humidity::uint:8', 'temperature::hex:8::01 humidity::hex:8::02');
/**
  {
    temperature: 226,
    humidity: 41
  }
**/

// reverse order in payload
parsed = parser('02290100e2','temperature::uint:16 humidity::uint:8', 'temperature::hex:8::01 humidity::hex:8::02');
/**
  {
    temperature: 226,
    humidity: 41
  }
**/

// missing fields
parsed = parser('0100e2','temperature::uint:16 humidity::uint:8', 'temperature::hex:8::01 humidity::hex:8::02');
/**
  {
    temperature: 226
  }
**/

Parse the syntax

var parser = require('cd.sigfox-parser')

var fields = parser.parseFields('lightAmbi::uint:16 temperature:2:int:8')

console.log(fields)
/**
[ { name: 'lightAmbi',
    offset: '',
    type: 'uint',
    length: '16',
    endianness: 'big-endian' },
  { name: 'temperature',
    offset: '2',
    type: 'int',
    length: '8',
    endianness: 'big-endian' } ]
**/

Formatstring

A formatstring consists of multiple fields. A field is defined by its name, its position in the message bytes, its length and its type :

the field name is an identifier including letters, digits and the '-' and '_' characters.
the byte index is the offset in the message buffer where the field is to be read from, starting at zero. If omitted, the position used is the current byte for boolean fields and the next byte for all other types. For the first field, an omitted position means zero (start of the message buffer)
Next comes the type name and parameters, which varies depending on the type :
boolean : parameter is the bit position in the target byte
char : parameter is the number of bytes to gather in a string
float : parameters are the length in bits of the value, which can be either 32 or 64 bits, and optionally the endianness for multi-bytes floats. Default is big endian. Decoding is done according to the IEEE 754 standard.
uint (unsigned integer) : parameters are the number of bits to include in the value, and optionally the endianness for multi-bytes integers. Default is big endian.
int (signed integer) : parameters are the number of bits to include in the value, and optionally the endianness for multi-bytes integers. Default is big endian.

Conditionstring

A conditionstring consists of multiple condition fields. It is used to find out if a field is present or not in the payload. It is defined by its name, its position in the message bytes, its length, its type and the value to find :

the field name is an identifier including letters, digits and the '-' and '_' characters.
the byte index is the offset in the message buffer where the field is to be read from, starting at zero. If omitted, the position used is the current byte for boolean fields and the next byte for all other types. For the first field, an omitted position means zero (start of the message buffer)
Next comes the type name and parameters, which varies depending on the type :
boolean : parameter is the bit position in the target byte
char : parameter is the number of bytes to gather in a string
float : parameters are the length in bits of the value, which can be either 32 or 64 bits, and optionally the endianness for multi-bytes floats. Default is big endian. Decoding is done according to the IEEE 754 standard.
uint (unsigned integer) : parameters are the number of bits to include in the value, and optionally the endianness for multi-bytes integers. Default is big endian.
int (signed integer) : parameters are the number of bits to include in the value, and optionally the endianness for multi-bytes integers. Default is big endian.
hex (hexadecimal) : parameters are the length in bits of the value(always 8 for now)

(cfr. Sigfox documentation)

Usage no npm install needed!