miniSMU Python Library

A comprehensive Python library for controlling the miniSMU MS01 Source Measure Unit (SMU) from Undalogic. This library provides both USB and WiFi connectivity options with support for advanced features including onboard I-V sweeps, protection settings, and high-precision measurements.

Features

• Dual Connectivity: USB (CDC) and WiFi (TCP) connections
• Complete SMU Control: Voltage/current sourcing, measurement, and channel management
• Advanced Measurement Features: Configurable oversampling ratio (OSR) for precision control
• Manual Current Range Control: Disable auto-ranging and select specific current ranges for optimal resolution
• Safety Protection: Current and voltage protection limits
• Onboard I-V Sweeps: Hardware-accelerated sweeps with progress monitoring (firmware v1.3.4+)
• 4-Wire (Kelvin) Measurements: High-accuracy measurements eliminating lead resistance errors (firmware v1.4.3+)
• WiFi Management: Network configuration, scanning, and auto-connect settings
• Data Streaming: Real-time continuous measurements
• Robust Communication: Handles chunked USB data and corruption gracefully

Installation

From Source

git clone https://github.com/Undalogic/minismu_py.git
cd minismu_py
pip install -e .

Dependencies

• pyserial - For USB communication
• tqdm - For progress bars (optional, used in examples)
• matplotlib - For plotting (optional, used in plotting examples)

Quick Start

Basic Usage (USB Connection)

from minismu_py import SMU, ConnectionType

# Connect to miniSMU via USB
with SMU(ConnectionType.USB, port="COM3") as smu:  # Adjust port for your system
    print(f"Connected to: {smu.get_identity()}")
    
    # Configure channel 1 for voltage sourcing
    smu.set_mode(1, "FVMI")  # Force Voltage, Measure Current
    smu.set_voltage(1, 1.2)  # Set 1.2V output
    smu.enable_channel(1)
    
    # Take measurements
    voltage, current = smu.measure_voltage_and_current(1)
    print(f"Measured: {voltage:.3f}V, {current*1000:.3f}mA")
    
    smu.disable_channel(1)

Basic Usage (WiFi Connection)

from minismu_py import SMU, ConnectionType

# Connect to miniSMU via WiFi
with SMU(ConnectionType.NETWORK, host="192.168.1.106") as smu:
    # Same usage as USB connection
    print(f"Connected to: {smu.get_identity()}")

Core Functionality

Connection Management

USB Connection

# Windows
smu = SMU(ConnectionType.USB, port="COM3")

# Linux/macOS
smu = SMU(ConnectionType.USB, port="/dev/ttyACM0")

Network Connection

smu = SMU(ConnectionType.NETWORK, host="192.168.1.106", tcp_port=3333)

Channel Configuration

Operating Modes

smu.set_mode(1, "FVMI")  # Force Voltage, Measure Current
smu.set_mode(1, "FIMV")  # Force Current, Measure Voltage

Output Control

smu.set_voltage(1, 3.3)      # Set 3.3V on channel 1
smu.set_current(1, 0.01)     # Set 10mA on channel 1
smu.enable_channel(1)        # Enable output
smu.disable_channel(1)       # Disable output

Protection Limits

smu.set_current_protection(1, 0.1)    # 100mA current limit in FVMI mode
smu.set_voltage_protection(1, 5.0)    # 5V voltage limit in FIMV

Measurements

Single Measurements

voltage = smu.measure_voltage(1)
current = smu.measure_current(1)
voltage, current = smu.measure_voltage_and_current(1)

Precision Control

# Set oversampling ratio (0-15, represents approx. 2^OSR samples)
smu.set_oversampling_ratio(1, 12)

Manual Current Range Control

By default, the miniSMU automatically switches between current ranges for optimal measurement. You can disable this and manually select a specific range for consistent measurements or optimal resolution.

Available Current Ranges

Range	Current Limit
0	± 1 µA
1	± 25 µA
2	± 650 µA
3	± 15 mA
4	± 180 mA

Manual Range Selection

from minismu_py import SMU, ConnectionType, CURRENT_RANGE_LIMITS

with SMU(ConnectionType.USB, port="COM3") as smu:
    # Disable autoranging and set a specific range
    smu.set_autorange(1, False)
    smu.set_current_range(1, 2)  # Range 2: ± 650 µA

    # Take measurements with fixed range
    voltage, current = smu.measure_voltage_and_current(1)

    # Re-enable autoranging when done
    smu.set_autorange(1, True)

Range Selection by Expected Current

# Automatically select the optimal range for your expected current
# This also disables autoranging automatically
selected_range = smu.set_current_range_by_limit(1, 10e-3)  # For up to 10 mA
print(f"Selected range: {selected_range}")  # Prints: 3 (± 15 mA range)

# For microamp-level measurements
selected_range = smu.set_current_range_by_limit(1, 500e-6)  # For up to 500 µA
print(f"Selected range: {selected_range}")  # Prints: 2 (± 650 µA range)

Accessing Range Limits Programmatically

from minismu_py import CURRENT_RANGE_LIMITS

# Get limit for a specific range
limit = smu.get_current_range_limit(2)  # Returns 650e-6 (650 µA)

# Or access the dictionary directly
for range_idx, limit in CURRENT_RANGE_LIMITS.items():
    print(f"Range {range_idx}: ± {limit * 1e6:.0f} µA" if limit < 1e-3
          else f"Range {range_idx}: ± {limit * 1e3:.0f} mA")

Data Streaming

smu.set_sample_rate(1, 1000)      # 1000 Hz sampling
smu.start_streaming(1)

# Read streaming data
for _ in range(100):
    channel, timestamp, voltage, current = smu.read_streaming_data()
    print(f"CH{channel}: {voltage:.3f}V, {current*1000:.3f}mA @ {timestamp}")

smu.stop_streaming(1)

Advanced Features

Onboard I-V Sweeps (Firmware v1.3.4+)

The miniSMU can perform I-V sweeps directly on the device, reducing communication overhead and providing more consistent timing.

Simple I-V Sweep

# Perform complete I-V sweep with progress monitoring
result = smu.run_iv_sweep(
    channel=1,
    start_voltage=-1.0,
    end_voltage=1.0,
    points=21,
    dwell_ms=100,
    monitor_progress=True
)

# Access results
for point in result.data:
    print(f"{point.voltage:.3f}V -> {point.current*1e6:.1f}µA")

Advanced Sweep Configuration

# Configure sweep parameters individually
smu.set_sweep_start_voltage(1, -0.5)
smu.set_sweep_end_voltage(1, 1.5)
smu.set_sweep_points(1, 100)
smu.set_sweep_dwell_time(1, 50)  # 50ms between points
smu.enable_sweep_auto_output(1)  # Auto enable/disable channel
smu.set_sweep_output_format(1, "JSON")  # CSV or JSON format

# Execute and monitor
smu.execute_sweep(1)

while True:
    status = smu.get_sweep_status(1)
    if status.status == "COMPLETED":
        break
    print(f"Progress: {status.current_point}/{status.total_points}")
    time.sleep(1)

# Get results
data = smu.get_sweep_data_json(1)  # Returns SweepResult object

Sweep Data Formats

JSON Format (includes metadata):

result = smu.get_sweep_data_json(1)
print(f"Config: {result.config.start_voltage}V to {result.config.end_voltage}V")
for point in result.data:
    print(f"{point.voltage:.3f}V, {point.current*1e6:.1f}µA")

CSV Format (simple data points):

data_points = smu.get_sweep_data_csv(1)
for point in data_points:
    print(f"{point.voltage:.3f}V, {point.current*1e6:.1f}µA")

4-Wire (Kelvin) Measurements (Firmware v1.4.3+)

4-wire sensing eliminates lead resistance errors for high-accuracy measurements by using separate force and sense connections.

How It Works

• CH1 acts as the source/force channel
• CH2 acts as the sense channel (high-impedance voltage measurement)
• Measurements on CH1 return CH1 current with CH2 voltage (true DUT voltage)
• OUTP1 ON/OFF controls both channels together in 4-wire mode

Basic Usage

# Enable 4-wire mode
smu.enable_fourwire_mode()

# Verify mode is active
if smu.get_fourwire_mode():
    print("4-wire mode enabled")

# Configure and enable output (controls both channels)
smu.set_mode(1, "FVMI")
smu.set_voltage(1, 1.0)
smu.enable_channel(1)

# Measure - voltage comes from CH2 sense, current from CH1
voltage, current = smu.measure_voltage_and_current(1)
print(f"True DUT voltage: {voltage:.6f}V, Current: {current*1000:.3f}mA")

# Disable when done
smu.disable_channel(1)
smu.disable_fourwire_mode()

Important Notes

• Cannot enable 4-wire mode while streaming or sweep is active
• CH2 commands are blocked while 4-wire mode is active
• Use disable_fourwire_mode() to restore independent channel operation

WiFi Management

Network Configuration

# Scan for networks
networks = smu.wifi_scan()
for network in networks:
    print(f"SSID: {network['ssid']}, Signal: {network['rssi']} dBm")

# Configure credentials
smu.set_wifi_credentials("MyNetwork", "MyPassword")
smu.enable_wifi()

# Auto-connect settings
smu.enable_wifi_autoconnect()
auto_enabled = smu.get_wifi_autoconnect_status()

WiFi Status

status = smu.get_wifi_status()
print(f"Connected: {status.connected}")
if status.connected:
    print(f"SSID: {status.ssid}")
    print(f"IP: {status.ip_address}")
    print(f"Signal: {status.rssi} dBm")

System Information

# Device identification
print(smu.get_identity())

# Temperature monitoring
adc_temp, ch1_temp, ch2_temp = smu.get_temperatures()
print(f"Temperatures: ADC={adc_temp}°C, CH1={ch1_temp}°C, CH2={ch2_temp}°C")

# Time synchronization
import time
smu.set_time(int(time.time() * 1000))  # Unix timestamp in milliseconds

Examples

The examples/ directory contains comprehensive examples demonstrating various features:

Basic Examples

• basic_usage.py - Simple voltage setting and measurement
• streaming_example.py - Real-time data streaming
• current_sweep.py - Manual current sweep implementation
• manual_current_range.py - Manual current range control and selection

I-V Sweep Examples

• usb_iv_sweep.py - Manual I-V sweep over USB with progress bars
• wifi_iv_sweep.py - Manual I-V sweep over WiFi
• onboard_iv_sweep.py - Hardware-accelerated onboard I-V sweeps
• fourwire_iv_sweep.py - 4-wire (Kelvin) I-V sweep for high-accuracy measurements
  • Simple sweep with progress monitoring
  • Advanced configuration examples
  • Data format comparison (CSV vs JSON)
  • Sweep abort demonstration
  • I-V curve plotting with matplotlib

Advanced Examples

• advanced_features.py - Comprehensive feature demonstration
  • OSR (oversampling) configuration
  • Protection limit settings
  • WiFi management
  • Complete measurement workflows

Running Examples

1. Adjust connection parameters in the example files:

   miniSMU_PORT = "COM3"  # Change to your USB port
   # or
   miniSMU_IP = "192.168.1.106"  # Change to your device IP
   

2. Run examples:

   python examples/basic_usage.py
   python examples/onboard_iv_sweep.py
   python examples/advanced_features.py
   

Data Classes

The library provides structured data classes for complex operations:

Sweep Operations

from minismu_py import SweepStatus, SweepConfig, SweepDataPoint, SweepResult

# Sweep status monitoring
status = smu.get_sweep_status(1)
print(f"Status: {status.status}")
print(f"Progress: {status.current_point}/{status.total_points}")
print(f"Elapsed: {status.elapsed_ms}ms")

# Sweep results
result = smu.get_sweep_data_json(1)
print(f"Configuration: {result.config}")
print(f"Data points: {len(result.data)}")

WiFi Status

from minismu_py import WifiStatus

status = smu.get_wifi_status()
print(f"Connected: {status.connected}")
print(f"Network: {status.ssid}")
print(f"IP: {status.ip_address}")
print(f"Signal: {status.rssi} dBm")

Error Handling

The library includes comprehensive error handling:

from minismu_py import SMUException

try:
    with SMU(ConnectionType.USB, port="COM3") as smu:
        # Your code here
        pass
except SMUException as e:
    print(f"SMU Error: {e}")
except Exception as e:
    print(f"General Error: {e}")

Common Issues and Solutions

Connection Issues

• USB: Verify the correct COM port/device path
• WiFi: Ensure device is on the same network and reachable
• Permissions: On Linux, you may need to add your user to the dialout group

Firmware Compatibility

• 4-Wire Mode: Requires firmware v1.4.3 or later
• Onboard I-V Sweeps: Requires firmware v1.3.4 or later
• Feature Support: Older firmware may not support all features
• Firmware Updates: Update your miniSMU firmware using the online update tool

Communication Issues

The library automatically handles:

• Chunked USB data transmission
• UTF-8 encoding errors
• JSON corruption in responses
• Network timeouts and reconnection

API Reference

Core Classes

SMU

The main interface class for miniSMU control.

Constructor:

SMU(connection_type, port="/dev/ttyACM0", host="192.168.1.1", tcp_port=3333)

Key Methods:

• get_identity() - Device identification
• set_mode(channel, mode) - Configure channel mode
• set_voltage(channel, voltage) - Set output voltage
• set_current(channel, current) - Set output current
• measure_voltage_and_current(channel) - Take measurements
• enable_channel(channel) / disable_channel(channel) - Output control

Protection and Precision

• set_current_protection(channel, limit) - Current protection limit
• set_voltage_protection(channel, limit) - Voltage protection limit
• set_oversampling_ratio(channel, osr) - Measurement precision (0-15)

Current Range Control

• set_autorange(channel, enabled) - Enable/disable automatic current range switching
• set_current_range(channel, range_index) - Manually set current range (0-4)
• set_current_range_by_limit(channel, max_current) - Auto-select range based on expected current (returns selected range)
• get_current_range_limit(range_index) - Get the current limit for a range index

I-V Sweep Methods

• run_iv_sweep() - Complete sweep operation
• configure_iv_sweep() - Setup sweep parameters
• execute_sweep(channel) - Start sweep execution
• get_sweep_status(channel) - Monitor progress
• get_sweep_data_json(channel) - Get structured results
• abort_sweep(channel) - Stop running sweep

4-Wire Measurement Methods

• enable_fourwire_mode() - Enable 4-wire mode (CH2 becomes sense channel)
• disable_fourwire_mode() - Disable 4-wire mode and restore independent channels
• get_fourwire_mode() - Query current 4-wire mode status

WiFi Methods

• wifi_scan() - Scan for networks
• set_wifi_credentials(ssid, password) - Configure network
• get_wifi_status() - Connection status
• enable_wifi_autoconnect() - Auto-connect control

Contributing

Contributions are welcome! Please feel free to submit issues, feature requests, or pull requests.

Development Setup

git clone https://github.com/Undalogic/minismu_py.git
cd minismu_py
pip install -e .[dev]  # Install with development dependencies

License

This project is licensed under the MIT License - see the LICENSE file for details.

Support

• Documentation: This README and inline code documentation
• Examples: Comprehensive examples in the examples/ directory
• Issues: Report bugs and request features via GitHub Issues
• Website: www.undalogic.com

Changelog

v0.4.1

• Fixed stop_streaming() and sweep data reads hanging indefinitely while the device is still streaming; they now raise SMUException after a time limit (#5)
• stop_streaming() now also stops a stream left running by a previous session

v0.4.0

• Fixed network (TCP) communication: responses are now buffered and reassembled correctly (previously anything larger than one packet, such as sweep data or WiFi scans, was truncated)
• Fixed CSV sweep data retrieval returning only the first data point
• Device-reported errors now raise SMUException instead of being silently ignored
• Fixed streaming desynchronising the connection: stop_streaming() now discards in-flight data, and stale data is cleared on connect
• Added support for firmware v1.5.0+ streaming packet format (extra trailing fields)
• Fixed get_wifi_status() always reporting connected=False
• Fixed run_iv_sweep() completion polling: no premature exit, no infinite loop, and a timeout with consistent abort handling
• Detect sweep data truncated by the firmware's ~5.7 kB TCP response limit (firmware v1.5.0 and earlier) and raise a descriptive error instead of returning incomplete data — see CHANGELOG.md for details

v0.3.2

• Better LAN reliability with firmware v1.4.6 and above

v0.3.1

• Added manual current range control for disabling auto-ranging and selecting specific ranges
• New methods: set_autorange(), set_current_range(), set_current_range_by_limit(), get_current_range_limit()
• New CURRENT_RANGE_LIMITS constant for programmatic access to range limits
• New example manual_current_range.py demonstrating manual range control

v0.3.0

• Added 4-wire (Kelvin) measurement mode for high-accuracy measurements (firmware v1.4.3+)
• New example fourwire_iv_sweep.py demonstrating 4-wire measurement techniques

v0.2.0

• Added onboard I-V sweep functionality (firmware v1.3.4+)
• Implemented OSR (oversampling ratio) control for precision measurements
• Added current and voltage protection settings
• Enhanced WiFi management with auto-connect features
• Improved USB communication with chunked data and corruption handling
• Added comprehensive examples and documentation

v0.1.0

• Initial release with basic SMU control
• USB and WiFi connectivity
• Basic measurement and sourcing functions
• Data streaming support
• WiFi configuration