sense_rec

Records sensor readings from the Raspberry Pi Sense HAT in real time, outputting the results to a file for later playback or analysis.

Synopsis

sense_rec [-h] [--version] [-q] [-v] [-l FILE] [-P] [-c CONFIG]
          [-d DURATION] [-f] output

Description

-h, --help

show this help message and exit

--version

show this program’s version number and exit

-q, --quiet

produce less console output

-v, --verbose

produce more console output

-l FILE, --log-file FILE

log messages to the specified file

-P, --pdb

run under PDB (debug mode)

-c FILE, --config FILE

the Sense HAT configuration file to use (default: /etc/RTIMULib.ini)

-d SECS, --duration SECS

the duration to record for in seconds (default: record until terminated with Control-C)

-f, --flush

flush every record to disk immediately; reduces chances of truncated data on power loss, but greatly increases disk activity

Examples

To record an experiment with the Sense HAT, simply execute sense_rec with the filename you wish to record the results:

$ sense_rec experiment.hat

By default, the recording will continue indefinitely. Press Control-C to terminate the recording. If you want to record for a specific duration, you can use the --duration option to specify the number of seconds:

$ sense_rec --duration 10 short_experiment.hat

This tool can be run simultaneously with scripts that use the Sense HAT. Simply start your script in one terminal, then open another to start sense_rec. Alternatively, you can use the shell’s job control facilities to start recording in the background:

$ sense_rec experiment.hat &
$ python experiment.py
...
$ kill %1

If - is specified as the output file, sense_rec will write its output to stdout. This can be used to reduce the disk space required for long output by piping the output through a compression tool like gzip:

$ sense_rec - | gzip -c - > experiment.hat.gz

When compressed in this manner the data typically uses approximately 3Kb per second (without gzip the recording will use approximately 10Kb of disk space per second). Use gunzip to de-compress the data for playback or analysis:

$ gunzip -c experiment.hat.gz | sense_play -

Alternatively, you can use this in conjunction with sense_csv to produce CSV output directly:

$ sense_rec - | sense_csv - experiment.csv

Be warned that CSV data is substantially larger than the binary format (CSV data uses approximately 25Kb per second).