SBF Parser

SBF Parser is a library to read SBF data from Septentrio devices.

SBF is private binary protocol of Septentrio trademark which uses in its own GNSS devices.

Firmwares and frames implemented:

4.10.1

• GNSS Attitude

  • AttCovEuler
  • AttEuler
  • AuxAntPositions
  • EndOfAtt

• GNSS Position Velocity Time

  • PVTCartesian
  • PVTGeodetic - Revision 2
  • PosCovCartesian
  • PosCovGeodetic
  • VelCovCartesian
  • VelCovGeodetic
  • DOP
  • PosCart
  • PosLocal
  • PosProjected
  • BaseVectorCart
  • BaseVectorGeod
  • PVTSupport
  • PVTSupportA
  • EndOfPVT

• Receiver Time

  • Receiver Time
  • xPPPSOffset

API

This library has two access points:

1. availableFirmwares() -> string[] firmwares
2. SBFParser([firmware: Firmware = '4.10.1', memory: boolean = false]) -> Parser Object

First function is to get available firmwares supported by the library.

Second is the Parser class to work with. It has three public attributes, and two methods.

Attributes:

• firmware -> firmware setted
• memory -> memory setted
• bufferLimit -> maximum internal buffer data in bytes supported
• bufferSize (read only) -> internal buffer data storage

Methods:

• addData(data: Buffer) -> To add data
• getFrames(): SBFResponse[] -> To get parsed frames. It returns an array of SBFResponse objects

How to use it

This is important

1. Importing parser

First of all, import the parser

import { SBFParser } from 'sbf-parser'

2. Creating an instance

Then you should instance a new parser object with one of this three ways

The constructor is this

SBFParser([firmware: Firmware = '4.10.1', memory: boolean = false])

1. firmware ('4.10.1' by default) is an string parameter with one of the supported firmwares To know supported firmwares just consult with

   import { availableFirmwares } from 'sbf-parser'
   const firmwares = availableFirmwares()

2. memory (disabled by default) is a boolean parameter to enable or disable memory

   • memory = false -> each time data is added, it clear internal buffer and add new one data
   • memory = true -> each time data is added, it is attached to the internal buffer

So the constructor could be of this three options:

• const parser = new SBFParser() -> firmware = '4.10.1', memory = false
• const parser = new SBFParser(fw) -> firmware = fw, memory = false
• const parser = new SBFParser(fw, mem) -> firmware = fw, memory = mem

3. Adding data

You can enable or disable memory whatever you want. If you enable it, you can add many times and then parsed when you need it. If you have memory disabled, each time you add data it will overwrite the previous data.

parser.memory = true
parser.memory = false

Data added have to be a Buffer instance or you get an exception.

const data1 = Buffer.from([...])
const data2 = Buffer.from([...])
// ...
parser.addData(data1)
parser.addData(data2)
// ...

4. Parsing data

Each time data is added, internally it is parsed. So parser.bufferLength is the remained data that cannot be parsed, maybe because is incompleted.

To get parsed frames is just

const frames = parser.getFrames()

Parsed frames are an array of objects, SBFResponse[], where each object, SBFResponse is like this

type SBFResponse = {
  name: string,
  number: number,
  version: number,
  frame: SBFFrame,
  buffer: Buffer,
}

type SBFFrame = {
  header: SBFHeader,
  time: SBFTime,
  body: SBFBody,
} 

export type SBFHeader = {
  sync: string,
  crc: number,
  id: SBFID,
  length: number
}

export type SBFID = {
  blockNumber: number,
  blockRevision: number
}

export interface SBFTime {
  tow: number | null,
  wnc: number | null,
  timestamp?: number | null,
  date?: string | null
}

export type SBFBody = object | null

When you get the parsed frames from the data, they are removed from parser objects.

parser.addData(data)
parser.getFrames().length // return x
parser.getFrames().length // return 0

Notes

bufferLimit it is used to stored an incompleted frame if memory is enabled. So you can add the needed it data later.

bufferLimit is set to 65535 bytes which is more than enough to store an incompleted frame.

It is not recommended you change its value if you don't understand well the protocol SBF or how it works.