XyloAudio 3 Power Measurements

The XyloAudio 3 development kit is equipped with Analog-to-Digital Converters (ADCs) for on-board power monitoring. The samna.boards.common.PowerMonitor class provides an interface for both one-shot and continuous power measurements. In continuous mode, power consumption is sampled at a user-defined target frequency. Power measurement results are reported as samna.unifirm.modules.events.PowerMeasurement events.

Each power measurement event includes:

• channel: The power channel being measured.

• value: The power consumption in watts.

The sampling period for the ADC is fixed at 1.080 ms, corresponding to a sample frequency of 925.9 Hz. To obtain the target frequency, the original signal is filtered with a moving average filter and then resampled, using linear interpolation if required.

The available measurement channels are described in samna.xyloAudio3.MeasurementChannels.

Note that samna.xyloAudio3.configuration.Debug.ram_access_enable has a big influence on power consumption. Therefore it is advised to disable RAM access whenever it’s not necessary.

Below is an example showing how to compute the average power consumption over a 3-second period. The following package versions are used:

- samna                 0.39.10

import samna

# Configure the board with a lower clock frequency to reduce power consumption.
config = samna.xyloAudio3.XyloAudio3TestBoardDefaultConfig()
config.main_clock_frequency = 25_000_000

# Open the device and connect to the power monitor.
board = samna.device.open_device("XyloAudio3TestBoard", defaultConfig=config)
power_monitor = board.get_power_monitor()
sink_pm = samna.graph.sink_from(power_monitor.get_source_node())
stopwatch = board.get_stop_watch()

# Start the stopwatch to add timestamps to the power measurement events.
stopwatch.start()

# Start sampling power on all channels at a target frequency of 50 Hz.
# Due to discretization the real frequency can vary slightly from 50 Hz.
real_freq = power_monitor.start_auto_power_measurement(50)

# Power measurements are streamed as PowerMeasurement events.
# Calculate the number of samples to collect over the specified duration (3 seconds).
duration_in_s = 3.0
channels = 3
n_samples = int(duration_in_s * real_freq) * channels
events = sink_pm.get_n_events(n_samples, timeout=int(duration_in_s + 1) * 1000)

# Stop the automatic power measurement.
power_monitor.stop_auto_power_measurement()

# Calculate the average power consumption for each channel.
counts = [0, 0, 0]
sums = [0, 0, 0]
for e in events:
    assert isinstance(e, samna.unifirm.modules.events.PowerMeasurement)
    sums[e.channel] += e.value
    counts[e.channel] += 1

# Compute the average power consumption in milliwatts (mW).
avgs = [sum/count * 1000 for sum, count in zip(sums, counts)]