Managing DBT Files with PACPUS

Pacpus framework offers a way to record data through DBT files. This is a binary format with timestamping functionalities.

Important notes

(1) For this tutorial we will work with the trunk version of the pacpusframework repository. If you are using a specific tag or branch please change trunk by your specific branch or tag path for each link below.

(2) To deal with DBT files you need to link you application with FileLib library. The source code can be found in this folder.

How to create a new DBT file

Step 1: identify the type and the structure of the data

First you must identify the type of your data in this file DbiteFileTypes.h. Remember note (1) and modify the path to fit with your installation of pacpusframework. If the type is already known by PACPUS, it is recommended to use it, else you need to create a new entry in this file.

For example, if you need to add a support BMP images, you can change this code block:

enum BasicType
{
    FILE_IMAGE = 0
    , FILE_CAN
    , FILE_TEXT
    , FILE_IMAGE3D
    , FILE_DBT_UNKNOWN          ///< Unknown file type
    , FILE_JPEG
    , STREAM8POSITION = 100
};

in:

enum BasicType
{
    FILE_IMAGE = 0
    , FILE_CAN
    , FILE_TEXT
    , FILE_IMAGE3D
    , FILE_DBT_UNKNOWN          ///< Unknown file type
    , FILE_JPEG
    , FILE_MYSTRUCT                  ///< New MYSTRUCT file format (remark: the number of the ID will be 6 here) 
    , STREAM8POSITION = 100
};

Warning, take care of using a free number in the file.

After this, you need to create the new structure of your data. It is a just a header file containing the C structure of the data. It is recommended to use standard types like uint32_t, int8_t, ... This types are available via cstdint.h file.

struct MYSTRUCT {
  uint32_t data1;
  int16_t data2; 
  uint8_t data3;
};

Step 2: creation of DBT file

First we create an instance of pacpus::DbiteFile.

pacpus::DbiteFile dbtFile_; //!< DBT file.

After we open the DBT file in writing mode with the open method that takes in parameters:

• the name of the DBT file
• the management mode of DBT file (WriteMode, ReadMode)
• the ID of data
• the size of the data structure

try {
    dbtFile_.open("my_struct_file.dbt", WriteMode, FILE_MYSTRUCT, sizeof(MYSTRUCT));
} catch (DbiteException & e) {
    cerr << "error opening dbt file: my_struct_file.dbt, " << e.what() << endl;
    return;
}

The my_struct_file.dbt file will be created in the current path of the application (often it is the folder where you have launched the application PacpusSensor).

step 3: writing data in DBT file

MYSTRUCT data; 
data.data1 = 22; 
data.data2 = 42; 
data.data3 = 11;

road_time_t time = road_time(); // the timestamp of the data 
road_timerange_t timerange = 0; // if not use, please set the value to 0

try {
   dbtFile_.writeRecord(time, timerange, (char *) &data, sizeof(data));
} catch (DbiteException & e) {
   cerr << "error writing data: " << e.what() << endl;
   return;
}

step 4: closing DBT file

At the end of your program don't forget to close correctly the DBT file:

dbtFile_.close();