Energy Analyzer

Measure energy, charge, and power statistics using an energy-analyzer net

Integrate energy and charge over time, or compute current/voltage/power statistics, using an energy-analyzer net connected to a Lager Box.

Syntax

lager energy NET_NAME read [OPTIONS]
lager energy NET_NAME stats [OPTIONS]

Commands

Command	Description
lager energy NET_NAME read	Integrate energy and charge over a duration
lager energy NET_NAME stats	Compute mean/min/max/std for current, voltage, and power

---

lager energy NET_NAME read

Integrate current and power over a configurable duration. Returns energy in joules and watt-hours, and charge in coulombs and amp-hours.

Options

Option	Description
--box BOX	Lagerbox name or IP address
--duration FLOAT	Integration duration in seconds (default: 10.0)
--help	Show help message and exit

Arguments

Argument	Description
NET_NAME	Name of the energy-analyzer net (optional if default is set)

Output

Energy 'POWER_METER' (10.0s):
  Energy:  12.500 mWh  (45.000 mJ)
  Charge:  3.472 mAh   (12.500 mC)

Examples

# Integrate over the default 10 seconds
lager energy POWER_METER read --box my-box

# Integrate over 60 seconds
lager energy POWER_METER read --box my-box --duration 60

# Use the default net
lager energy read

---

lager energy NET_NAME stats

Compute mean, minimum, maximum, and standard deviation for current, voltage, and power over a configurable duration.

Options

Option	Description
--box BOX	Lagerbox name or IP address
--duration FLOAT	Measurement duration in seconds (default: 1.0)
--help	Show help message and exit

Arguments

Argument	Description
NET_NAME	Name of the energy-analyzer net (optional if default is set)

Output

Stats 'POWER_METER' (1.0s):
  Current (A):  mean=0.015200  min=0.014900  max=0.015600  std=0.000120
  Voltage (V):  mean=3.301000  min=3.300500  max=3.301500  std=0.000200
  Power   (W):  mean=0.050175  min=0.049185  max=0.051516  std=0.000400

Examples

# Stats over the default 1 second
lager energy POWER_METER stats --box my-box

# Stats over 5 seconds for better averaging
lager energy POWER_METER stats --box my-box --duration 5

# Use the default net
lager energy stats

---

Default Net

To avoid specifying the net name each time:

lager defaults add --energy-net POWER_METER

Then:

lager energy read
lager energy stats

Supported Hardware

Manufacturer	Model	Net Type	USB VID:PID
Joulescope	JS220	energy-analyzer	16d0:10ba
Nordic Semiconductor	PPK2	energy-analyzer	1915:c00a

For instantaneous power readings only, see Watt Meter.

Scripting Examples

Energy Budget Verification

#!/bin/bash
# Verify a device's energy consumption during a 10-second test
RESULT=$(lager energy POWER_METER read --box my-box --duration 10)
echo "$RESULT"

# Extract mWh value for pass/fail
MWH=$(echo "$RESULT" | grep -oP '[\d.]+(?= mWh)')
if (( $(echo "$MWH > 50" | bc -l) )); then
    echo "FAIL: Energy consumption too high: ${MWH} mWh"
    exit 1
fi
echo "PASS: Energy within budget"

Sleep Current Verification

#!/bin/bash
# Check sleep current is below 100 uA
RESULT=$(lager energy POWER_METER stats --box my-box --duration 5)
echo "$RESULT"

# Extract mean current in amps, convert to uA
CURRENT_A=$(echo "$RESULT" | grep "Current" | grep -oP 'mean=\K[\d.]+')
CURRENT_UA=$(echo "$CURRENT_A * 1000000" | bc -l)

if (( $(echo "$CURRENT_UA > 100" | bc -l) )); then
    echo "FAIL: Sleep current ${CURRENT_UA} uA exceeds 100 uA limit"
    exit 1
fi
echo "PASS: Sleep current ${CURRENT_UA} uA"

Troubleshooting

Error	Cause	Fix
Timeout (120s)	Device disconnected or measurement too long	Check USB connection; reduce --duration
Connection refused	Box service not running	Check box: lager hello --box <box>
Device not found	Energy analyzer not detected	Verify device is connected: lager instruments --box <box>
Net not found	Net not configured as energy-analyzer	Check net type: lager nets --box <box>

Notes

• The default command timeout is 120 seconds to accommodate long integrations
• Joulescope JS220 samples continuously; accuracy improves with longer durations
• Nordic PPK2 operates in source mode (supplies a configurable voltage 0.8–5V and measures current); voltage readings reflect the configured value
• Use lager instruments --box <box> to verify the device is detected
• Net names refer to names assigned when configuring your testbed
• Use lager nets to see available energy-analyzer nets