Power profiler

Power Profiler Skill

Expert skill for power consumption measurement, analysis, and optimization in embedded systems. Provides integration with power analyzer tools and deep expertise in low-power design techniques.

Overview

The Power Profiler skill enables comprehensive power analysis for embedded systems, supporting:

• Power analyzer tool integration (Otii Arc, Nordic PPK2, Joulescope)
• Current measurement configuration and calibration
• Power mode transition analysis
• Battery life estimation calculations
• Power profile comparison and trending
• Peripheral power contribution analysis
• Sleep mode leakage identification
• Energy-per-operation measurements

Capabilities

1. Power Measurement Configuration

Configure and calibrate power measurement hardware:

// Example: Configure Otii Arc power analyzer
const powerConfig = {
  analyzer: 'otii-arc',
  sampleRate: 4000,        // Hz
  currentRange: 'auto',     // auto, low (uA), high (mA)
  voltageOutput: 3.3,       // Supply voltage
  triggerMode: 'gpio',      // gpio, serial, manual
  triggerPin: 'GPI1'
};

2. Power State Analysis

Analyze power consumption across different operating states:

## Power State Profile

| State | Current (avg) | Duration | Energy |
|-------|---------------|----------|--------|
| Active | 15.2 mA | 50 ms | 760 uJ |
| Processing | 45.3 mA | 10 ms | 453 uJ |
| Radio TX | 120 mA | 5 ms | 600 uJ |
| Sleep | 2.5 uA | 935 ms | 2.3 uJ |
| **Total Cycle** | - | 1000 ms | **1815.3 uJ** |

Average Current: 1.815 mA
Battery Life (1000 mAh): 551 hours (23 days)

3. Power Mode Transition Analysis

Identify and analyze power state transitions:

• Wake-up latency measurement
• Sleep entry timing
• Transition energy overhead
• Unexpected wake-up detection
• Power state sequence verification

4. Peripheral Power Contribution

Break down power consumption by peripheral:

## Peripheral Power Breakdown

| Peripheral | Active Current | Sleep Current | Contribution |
|------------|----------------|---------------|--------------|
| MCU Core | 8.5 mA | 1.2 uA | 35% |
| Radio (BLE) | 6.2 mA | 0.5 uA | 25% |
| Sensors | 3.8 mA | 0.8 uA | 16% |
| Display | 4.2 mA | 0.1 uA | 17% |
| Other | 1.5 mA | 0.4 uA | 7% |

5. Battery Life Estimation

Calculate expected battery life for various usage scenarios:

// Battery life estimation parameters
const batteryEstimate = {
  batteryCapacity: 230,     // mAh (CR2032)
  dutyCycle: {
    activePeriod: 100,      // ms
    sleepPeriod: 9900,      // ms
    transmitCount: 1        // per cycle
  },
  currentProfile: {
    active: 15.0,           // mA
    sleep: 2.5,             // uA
    transmit: 120.0         // mA
  },
  derating: 0.85            // 85% capacity utilization
};

// Calculated: 2.3 years battery life

Process Integration

This skill integrates with the following processes:

Process	Integration Point
power-consumption-profiling.js	Primary execution - all phases
low-power-design.js	Measurement and validation phases
real-time-performance-validation.js	Power budget verification

Tool Integration

Supported Power Analyzers

Tool	Features	Connection
Otii Arc	High precision, automation API	USB, REST API
Nordic PPK2	Source/ampere meter modes	USB, nRF Connect
Joulescope	Real-time streaming, triggers	USB, Python API
Keysight N6705C	Multi-channel, high accuracy	GPIB, USB, LAN
Qoitech Otii	Cloud integration, sharing	USB, Otii Desktop

Data Export Formats

• CSV time-series data
• JSON power profiles
• PNG/SVG visualizations
• Interactive HTML reports
• Otii project files (.otii)
• Joulescope capture files (.jls)

Workflow

1. Setup Measurement Environment

# Verify power analyzer connection
otii-cli device list

# Configure measurement parameters
otii-cli project create \
  --name "power-profile-$(date +%Y%m%d)" \
  --voltage 3.3 \
  --current-range auto

2. Capture Power Profile

# Start recording with GPIO trigger
otii-cli recording start \
  --trigger gpio:GPI1:rising \
  --duration 10s

# Or use serial trigger
otii-cli recording start \
  --trigger serial:START \
  --stop-trigger serial:STOP

3. Analyze Results

# Export measurement data
otii-cli recording export \
  --format csv \
  --output power-data.csv

# Generate statistics
otii-cli statistics \
  --markers state:active,state:sleep \
  --output stats.json

4. Generate Report

The skill generates comprehensive power analysis reports including:

• Executive summary with key metrics
• State-by-state power breakdown
• Transition timing analysis
• Battery life projections
• Optimization recommendations
• Comparison with targets/baselines

Output Schema

{
  "summary": {
    "averageCurrent_mA": 1.815,
    "peakCurrent_mA": 120.0,
    "sleepCurrent_uA": 2.5,
    "estimatedBatteryLife_hours": 551
  },
  "powerStates": [
    {
      "name": "active",
      "current_mA": 15.2,
      "duration_ms": 50,
      "energy_uJ": 760
    }
  ],
  "transitions": [
    {
      "from": "sleep",
      "to": "active",
      "latency_us": 125,
      "energy_uJ": 1.2
    }
  ],
  "peripheralBreakdown": {
    "mcu": { "active_mA": 8.5, "sleep_uA": 1.2 },
    "radio": { "active_mA": 6.2, "sleep_uA": 0.5 }
  },
  "recommendations": [
    "Reduce radio TX power by 3dB to save 15% energy",
    "Enable peripheral clock gating during sleep"
  ],
  "artifacts": [
    "power-profile.csv",
    "power-report.html",
    "waveform.png"
  ]
}

Best Practices

Measurement Setup

• Use kelvin sense connections for accurate voltage measurement
• Minimize wire length between analyzer and DUT
• Ensure stable power supply to analyzer
• Allow thermal stabilization before measurement

Calibration

• Zero-offset calibration before each session
• Verify measurement accuracy with known load
• Document measurement uncertainty

Analysis

• Use markers to identify power states
• Compare against power budget requirements
• Track power metrics across firmware versions
• Document measurement conditions

References

• Nordic PPK2 User Guide
• Joulescope User Guide
• Otii Arc Documentation
• "Power Management for Internet of Things" - ARM
• Low-Power Design Methodology Manual

MCP Server Integration

Compatible MCP servers for enhanced functionality:

Server	Purpose
embedded-debugger-mcp	Coordinate debug probes with power measurement
serial-mcp-server	Serial trigger synchronization
tinymcp	Device state monitoring

See Also

• low-power-design.js - Low-power design implementation process
• power-consumption-profiling.js - Full power profiling workflow
• AG-006: Power Optimization Expert agent