BWSI piPACT Reference Code

BWSI piPACT Reference/instructor developed code for Raspberry Pi based BLE RSSI measurement collection. Modified by Winner-exe.

Requirements

Stated versions are tested and validated. Newer or older versions are not guaranteed to work.

• Python 3.7.3
• pybluez[ble]
• gattlib
• numpy
• pandas
• pyyaml
• sense_hat

Installation

1. Install the requirement.
2. Clone the repository.
3. Navigate into the piPACT folder that was created.

   pi@raspberrypi:~ $ cd piPACT

4. Test the repository by attempting to import the piPACT reference code without error.

   pi@raspberrypi:~/piPACT $ python3
   Python 3.7.3 (default, Dec 20 2019, 18:57:59) 
   [GCC 8.3.0] on linux
   Type "help", "copyright", "credits" or "license" for more information.
   >>> import pi_pact
   >>>

Usage

This section addresses how to use the reference code to instantiate either a beacon advertiser or beacon scanner from the command line/terminal. Both are accessed from the same command line interface and use a common configuration file. Both also implement "user commanded stop" functionality via a simple control file mechanism explained in each section.

pi@raspberrypi:~ $ sudo python3 pi_pact.py --help
usage: pi_pact.py [-h] (-a | -s) [--config_yml CONFIG_YML]
                  [--control_file CONTROL_FILE] [--scan_prefix SCAN_PREFIX]
                  [--timeout TIMEOUT] [--uuid UUID] [--major MAJOR]
                  [--minor MINOR] [--tx_power TX_POWER] [--interval INTERVAL]
                  [--revist REVIST] [--distance DISTANCE] [--use_sense_hat USE_SENSE_HAT]

BLE beacon advertiser or scanner. Command line arguments will override their
corresponding value in a configuration file if specified.

optional arguments:
  -h, --help            show this help message and exit
  -a, --advertiser      Beacon advertiser mode.
  -s, --scanner         Beacon scanner mode.
  --config_yml CONFIG_YML
                        Configuration YAML.
  --control_file CONTROL_FILE
                        Control file.
  --scan_prefix SCAN_PREFIX
                        Scan output file prefix.
  --timeout TIMEOUT     Timeout (s) for both beacon advertiser and scanner
                        modes.
  --uuid UUID           Beacon advertiser UUID.
  --major MAJOR         Beacon advertiser major value.
  --minor MINOR         Beacon advertiser minor value.
  --tx_power TX_POWER   Beacon advertiser TX power.
  --interval INTERVAL   Beacon advertiser interval (ms).
  --revist REVIST       Beacon scanner revisit interval (s).
  --distance DISTANCE   Pre-measured distance (m).
  --use_sense_hat USE_SENSE_HAT Toggles use of sense hat.

Configuration

The configuration file is of the YAML format. It is provided with a default configuration which you should change to suit your needs. You will need to reference in-line comments and external module documentation to fully understand all configuration options.

The configuration YAML will only be used if specified as a command line argument. Many indiviudal configuration options can be overwritten by command line provided arguments.

# Configuration file for piPACT reference collection software

# Settings for beacon advertisment
advertiser:
  control_file: 'advertiser_control' # Control file which stops beacon advertisement before timeout
  timeout: 20 # Advertisement timeout (s)
  uuid: '' # UUID, major, and minor values to advertise
  major: 1
  minor: 1 
  tx_power: 1 # Tx power at which to advertise
  interval: 200 # Interval at which advertise (ms)

# Settings for beacon scanner
scanner:
  control_file: 'scanner_control' # Control file which stops beacon scanner before timeout
  scan_prefix: 'pi_pact_scan' # Prefix to attach to scan output files
  timeout: 20 # Scanning timeout (s)
  revisit: 1 # Interval at which to scan (s)
  distance: 0.2 # Pre-measured distance between devices (m)
  use_sense_hat: True # Toggles use of sense hat.
  filters: # Filters
    ADDRESS:
    RSSI:
    
# Logger configuration
logger:
  name: &name 'pi_pact.log'
  config:
    version: 1
    formatters:
      full:
        format: '%(asctime)s   %(module)-10s   %(levelname)-8s   %(message)s'
      brief:
        format: '%(asctime)s   %(levelname)-8s   %(message)s'
    handlers:
      console:
        class: 'logging.StreamHandler'
        level: 'INFO'
        formatter: 'brief'
      file:
        class: 'logging.handlers.TimedRotatingFileHandler'
        level: 'DEBUG'
        formatter: 'full'
        filename: *name
        when: 'H'
        interval: 1
    loggers:
      *name:
        level: 'DEBUG' # Effective logging level
        handlers:
          - 'console'
          - 'file'

Filters

Filters are a special configuration specific to a scanner and only available via the configuration YAML. They allow users to filter received data such that only data that meets all specified filters. Filters are specified as key-value pairs where the key is the data field to filter on and the value is filter specification (value/bounds). If no filters are specified then all received data is logged.

There are two (2) categories of filters available:

1. ID filters: Filter data based on exact match. These filters are associated with parts of a beacon advertisement that is fixed and unique to a beacon's identity. This filtering is done using pandas.DataFrame.isin functionality. Available ID filters are
   • ADDRESS - Advertiser's beacon hardware address
   • UUID - Advertiser's Universally Unique Identifier (UUID)
   • MAJOR - Advertiser's Major value
   • MINOR - Advertiser's Minor value
   • TX POWER - Avertiser's stated Transmit (Tx) Power
2. Measurement filters: Filter data based on within-range match. These filters are associated with measured values of the beacon advertisement that may vary and have no direct correlation with a beacon's identity. These are specified as 2-element list where the 1st element is the lower bound while the 2nd element is the upper bound. This filtering is done using pandas.DataFrame.query functionality. Available measurement filters are
   • TIMESTAMP - Time window specified by a beginning and end timestamp.
   • RSSI - Range of Received Signal Strength Indicator (RSSI) values (dBm)

Below is an example configuration of ADDRESS and RSSI filters. Note that the RSSI filter as an ID Filter value is a 2-element list.

# Settings for beacon scanner
scanner:
  control_file: 'scanner_control' # Control file which stops beacon scanner before timeout
  scan_prefix: 'pi_pact_scan' # Prefix to attach to scan output files
  timeout: 20 # Scanning timeout (s)
  revisit: 1 # Interval at which to scan (s)
  filters: # Filters
    ADDRESS: AA:BB:CC:DD:EE:FF
    RSSI:
      - -55
      - 0

Advertiser

An advertiser can be started in one of two primary modes concerning when and how to stop the advertiser. In either case, the user commanded stop is available.

No Timeout

In this mode, the advertiser will run infinitely until a user commanded stop is specified via the advertiser control file. The advertiser control file is specified either in the configuration YAML or overwritten by the command line argument.

1. Start the advertiser. The addition of the & flag causes the command to be executed in the background. This allows the user to retain control of the command line which makes commanding the advertiser to stop much easier.

   pi@raspberrypi:~ $ sudo python3 pi_pact.py -a --config_yml pi_pact_config.yml &
   [1] 2083

2. Observe the informational log messages.

   pi@raspberrypi:~ $ 2020-06-20 10:12:42,594   INFO       Beacon advertiser mode selected.
   2020-06-20 10:12:42,597   INFO       Initialized beacon advertiser.
   2020-06-20 10:12:42,599   INFO       Starting beacon advertiser with timeout None.

3. Stop the advertiser by placing any non-zero value into the advertiser control file.

   pi@raspberrypi:~ $ echo 1 > advertiser_control
   pi@raspberrypi:~ $ 2020-06-20 10:12:58,623   INFO       Stopping beacon advertiser.

Timeout

In this mode, the advertiser will run either until the specified timeout or until a user commanded stop is specified via the advertiser control file. The advertiser control file is specified either in the configuration YAML or overwritten by the command line argument.

1. Start the advertiser. The addition of the & flag causes the command to be executed in the background. This allows the user to retain control of the command line which makes commanding the advertiser to stop much easier.

   pi@raspberrypi:~ $ sudo python3 pi_pact.py -a --config_yml pi_pact_config.yml --timeout 20 &
   [1] 2282

2. Observe the informational log messages.

   pi@raspberrypi:~ $ 2020-06-20 10:26:10,268   INFO       Beacon advertiser mode selected.
   2020-06-20 10:26:10,270   INFO       Initialized beacon advertiser.
   2020-06-20 10:26:10,273   INFO       Starting beacon advertiser with timeout 20.0.

3. Stop the advertiser either by waiting for the timeout

   2020-06-20 10:26:30,301   INFO       Stopping beacon advertiser.

   or by placing any non-zero value into the advertiser control file.

   pi@raspberrypi:~ $ echo 1 > advertiser_control
   pi@raspberrypi:~ $ 2020-06-20 10:26:30,301   INFO       Stopping beacon advertiser.

Scanner

A scanner can be started in one of two primary modes concerning when and how to stop the scanner. In either case, the user commanded stop is available.

No Timeout

In this mode, the scanner will run infinitely until a user commanded stop is specified via the scanner control file. The scanner control file is specified either in the configuration YAML or overwritten by the command line argument.

1. Start the scanner. The addition of the & flag causes the command to be executed in the background. This allows the user to retain control of the command line which makes commanding the scanner to stop much easier.

   pi@raspberrypi:~ $ sudo python3 pi_pact.py -s --config pi_pact_config.yml &
   [1] 2083

2. Observe the informational log messages.

   pi@raspberrypi:~ $ 2020-06-20 10:12:42,594   INFO       Beacon scanner mode selected.
   2020-06-20 10:12:42,597   INFO       Initialized beacon scanner.
   2020-06-20 10:12:42,599   INFO       Starting beacon scanner with timeout None.

3. Stop the scanner by placing any non-zero value into the scanner control file.

   pi@raspberrypi:~ $ echo 1 > scanner_control
   pi@raspberrypi:~ $ 2020-06-20 10:12:58,623   INFO       Stopping beacon scanner.

Timeout

In this mode, the scanner will run either until the specified timeout or until a user commanded stop is specified via the scanner control file. The scanner control file is specified either in the configuration YAML or overwritten by the command line argument.

1. Start the scanner. The addition of the & flag causes the command to be executed in the background. This allows the user to retain control of the command line which makes commanding the scanner to stop much easier.

   pi@raspberrypi:~ $ sudo python3 pi_pact.py -s --config pi_pact_config.yml --timeout 20 &
   [1] 2282

2. Observe the informational log messages.

   pi@raspberrypi:~ $ 2020-06-20 10:26:10,268   INFO       Beacon scanner mode selected.
   2020-06-20 10:26:10,270   INFO       Initialized scanner advertiser.
   2020-06-20 10:26:10,273   INFO       Starting beacon scanner with timeout 20.0.

3. Stop the advertiser either by waiting for the timeout

   2020-06-20 10:26:30,301   INFO       Stopping beacon scanner.

   or by placing any non-zero value into the scanner control file.

   pi@raspberrypi:~ $ echo 1 > scanner_control
   pi@raspberrypi:~ $ 2020-06-20 10:26:30,301   INFO       Stopping beacon scanner.

Output

The only explicit output of this code are the published log messages (console and log file) and CSV files containing the beacons found by the beacon scanner. The default (and expected) format/headers of this CSV file are as follow.

• SCAN: The scan number during which this beacon advertisement was received.
• ADDRESS: The address of the beacon.
• TIMESTAMP: Timestamp (in beacon scanner device's time) at which this beacon advertisement was received.
• UUID: The UUID sent in beacon advertisement.
• MAJOR: The major value sent in beacon advertisement.
• MINOR: The minor value sent in beacon advertisement.
• TX POWER: The Tx power value sent in beacon advertisement.
• RSSI: The measured RSSI (dBm) of the received beacon advertisement.
• DISTANCE: The pre-measured distance (m) between the devices.

The following headers are only present if --use_sense_hat is set to True (enabled by default):

• TEMPERATURE: The temperature (degrees Celsius) measured using the humidity sensor.
• HUMIDITY: The percentage of relative humidity measured using the humidity sensor.
• PRESSURE: The pressure (millibars) measured using the pressure sensor.
• PITCH: The angle (degrees) measured using the aircraft principal axis of pitch.
• ROLL: The angle (degrees) measured using the aircraft principal axis of roll.
• YAW: The angle (degrees) measured using the aircraft principal axis of yaw.

Repeated Execution

The script pi_pact_repeat.py can be used to repeatedly execute pi_pact.py. This script can take the argument DISTANCE_INCREMENT (default value of 0) to automatically adjust the pre-measured distance with each run, although users should make sure they move the pis to their correct positions in between runs. Passing the argument WAIT_INTERVAL (default value of 60) can give the user more time to reposition the pis in between runs.

pi@raspberrypi:~ $ sudo python3 pi_pact_repeat.py --help
usage: pi_pact_repeat.py [-h] [--distance_increment DISTANCE_INCREMENT]
                         --distance DISTANCE --timeout TIMEOUT
                         [--wait_interval WAIT_INTERVAL]
                         (--distance_final DISTANCE_FINAL | --timeout_final TIMEOUT_FINAL | --iterations ITERATIONS)
                         (-a | -s) [--config_yml CONFIG_YML]
                         [--control_file CONTROL_FILE]
                         [--scan_prefix SCAN_PREFIX] [--uuid UUID]
                         [--major MAJOR] [--minor MINOR] [--tx_power TX_POWER]
                         [--interval INTERVAL] [--revist REVIST] [--use_sense_hat USE_SENSE_HAT]

Script to run pi_pact.py repeatedly with variable distance and interval
increments

optional arguments:
  -h, --help            show this help message and exit
  --distance_increment DISTANCE_INCREMENT
                        The change in distance between runs (m).
  --distance DISTANCE   Initial pre-measured distance between the devices (m).
  --timeout TIMEOUT     Timeout (s) for both beacon advertiser and scanner
                        modes.
  --wait_interval WAIT_INTERVAL
                        The wait in between runs (s).
  --distance_final DISTANCE_FINAL
                        The final distance to run pi_pact.py on.
  --timeout_final TIMEOUT_FINAL
                        The total timeout for this script (s).
  --iterations ITERATIONS
                        The number of times to run pi_pact.py
  -a, --advertiser      Beacon advertiser mode.
  -s, --scanner         Beacon scanner mode.
  --config_yml CONFIG_YML
                        Configuration YAML.
  --control_file CONTROL_FILE
                        Control file.
  --scan_prefix SCAN_PREFIX
                        Scan output file prefix.
  --uuid UUID           Beacon advertiser UUID.
  --major MAJOR         Beacon advertiser major value.
  --minor MINOR         Beacon advertiser minor value.
  --tx_power TX_POWER   Beacon advertiser TX power.
  --interval INTERVAL   Beacon advertiser interval (ms).
  --revist REVIST       Beacon scanner revisit interval (s)
  --use_sense_hat USE_SENSE_HAT Toggles use of sense hat.