Power Measurement

The SpiNNaker2 STM interface provides comprehensive power measurement capabilities through the PowerMeasurement and PowerResults classes.

Basic Usage

To measure power while running an application on SpiNNaker2:

from spinnaker2_stm.read_power import PowerMeasurement, PowerResults

data_file = "power_record.log"
power_meter = PowerMeasurement(
    data_file, 
    rdout_delay=100,
    ser_path="/dev/ttyS2_192_168_2_33", 
    get_all=True
)

with power_meter:
    # run experiment or testcase on SpiNNaker2 chip

Analyzing Results

The measurement data can be analyzed in two ways:

From the same script:

power_results = power_meter.get_results()

Or in a new script:

power_results = PowerResults(data_file)

Available Measurements

The PowerResults class provides access to:

Raw shunt voltages (μV): power_results.raw_data
Shunt currents (mA): power_results.shunt_current
Power consumption (mW): power_results.shunt_power

Each measurement includes data for different power domains:

PL05: 0.5V power lane
PL08: 0.8V power lane
PLL: PLL power (0.8V)
IO: I/O power (1.8V)
Q: Q power (1.1V)

Plotting

Plot power consumption over time:

import matplotlib.pyplot as plt

# Plot shunt power over time
power_results.shunt_power.plot(xlabel="time [s]", ylabel="power [mW]")
plt.show()

Energy Calculation

Calculate total energy consumption:

total_energy = power_results.total_energy()
print(f"Total energy: {total_energy:.3f} J")

Advanced Configuration

PowerMeasurement Parameters

The PowerMeasurement class accepts the following parameters:

PowerMeasurement(
    file_path: str,          # Path where measurement data will be saved
    rdout_delay: int,        # Delay between measurements in milliseconds
    ser_path: str = '/dev/ttyACM0',  # Path to serial interface
    get_all: bool = False    # Whether to measure all power rails
)

Shunt Resistor Values

The following shunt resistor values are used for measurements:

R_PL08_SHUNT     = 0.008  # Ohm (R570)
R_PL05_SHUNT     = 0.03   # Ohm (R569)
R_VDDPLL08_SHUNT = 0.05   # Ohm (R131)
R_VDDIO18_SHUNT  = 0.05   # Ohm (R572)
R_VDDQ11_SHUNT   = 0.05   # Ohm (R571)

Command Line Interface

The package also provides a command-line interface for power measurements:

python -m spinnaker2_stm.measure_base [OPTIONS]

Options:
  --plotv         Plot shunt voltage [uV] over time [s]
  --ploti         Plot shunt current over time [s]
  --plotp         Plot shunt power over time [s]
  --csv           Write out data file as CSV
  --get_all       Write out all shunt voltages (default: only 0V5 & 0V8)
  --num_dpoints   Number of data points (default: 100)
  --rdout_delay   Delay between data points [ms] (default: 100)
  --runtime       Measurement runtime [ms]
  --freq_pe       PE frequency (default: 150)
  --freq_noc      NoC frequency (default: 150)
  --ser_path      Path to serial STM interface (default: /dev/ttyACM0)

Example: Complete Measurement Script

Here's a complete example showing how to perform power measurements and analyze the results:

from spinnaker2_stm.read_power import PowerMeasurement, PowerResults
import matplotlib.pyplot as plt

# Configure measurement
data_file = "power_record.log"
power_meter = PowerMeasurement(
    data_file,
    rdout_delay=100,  # 100ms between measurements
    get_all=True      # measure all power rails
)

# Perform measurement
with power_meter:
    # Your SpiNNaker2 code here
    pass

# Analyze results
power_results = power_meter.get_results()

# plot shunt power over time
power_results.shunt_power.plot(xlabel="time [s]", ylabel="power [mW]")
plt.show()

# print total energy
print(f"total energy: {power_results.total_energy():.3f} J")