Stream Buffer API¶
- class joulescope.v1.stream_buffer.StreamBuffer(duration, frequency, device, output_frequency=None)[source]¶
Efficient real-time Joulescope data buffering.
- Parameters:
duration – The total length of the buffering in seconds.
- data_get(start, stop, increment=None, out=None)[source]¶
Get the samples with statistics.
- Parameters:
start – The starting sample id (inclusive).
stop – The ending sample id (exclusive).
increment – The number of raw samples.
out – The optional output np.ndarray((N, STATS_FIELD_COUNT), dtype=DTYPE) to populate with the result. None (default) will construct and return a new array.
- Returns:
The np.ndarray((N, STATS_FIELD_COUNT), dtype=DTYPE) data.
This method provides fast access to statistics data, primarily for graphical display. Applications should prefer using
samples_get()
which provides metadata along with the samples.
- property sample_id_range¶
Get the range of sample ids currently available in the buffer.
- Returns:
Tuple of sample_id start, sample_id end. Start and stop follow normal python indexing: start is inclusive, end is exclusive
- samples_get(start, stop, fields=None)[source]¶
Get exact sample data without any skips or reductions.
- Parameters:
start – The starting sample id (inclusive).
stop – The ending sample id (exclusive).
fields –
The single field or list of field names to return. None (default) is equivalent to [‘current’, ‘voltage’, ‘power’, ‘current_range’, ‘current_lsb’, ‘voltage_lsb’]. The available fields are:
raw: The raw u16 data from Joulescope. Equivalent to self.raw_get(start, stop)
raw_current: The raw 14-bit current data in LSBs.
raw_voltage: The raw 14-bit voltage data in LSBs.
current: The calibrated float32 current data array in amperes.
voltage: The calibrated float32 voltage data array in volts.
current_voltage: The calibrated float32 Nx2 array of current, voltage.
power: The calibrated float32 power data array in watts.
bits: The (voltage_lsb << 5) | (current_lsb << 4) | current_range
current_range: The current range. 0 = 10A, 6 = 18 uA, 7=off.
current_lsb: The current LSB, which can be assign to a general purpose input.
voltage_lsb: The voltage LSB, which can be assign to a general purpose input.
- Returns:
The dict containing top-level ‘time’ and ‘signals’ keys. The ‘time’ value is a dict contain the timing metadata for these samples. The ‘signals’ value is a dict with one key for each field in fields. Each field value is also a dict with entries ‘value’ and ‘units’. However, if single field string is provided to fields, then just return that field’s value.
- statistics_get(start, stop, out=None)[source]¶
Get exact statistics over the specified range.
- Parameters:
start – The starting sample_id (inclusive).
stop – The ending sample_id (exclusive).
out – The optional output np.ndarray(STATS_FIELD_COUNT, dtype=DTYPE). None (default) creates and outputs a new record.
- Returns:
The tuple of (np.ndarray(STATS_FIELD_COUNT, dtype=DTYPE), [start, stop]). The values of start and stop will be constrained to the available range.