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Master Board

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Overview

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Key Features

• Ethernet communication with control PC
• SPI communication with Micro Driver boards at 1kHz
• IMU interface for inertial measurement unit
• Power distribution to Micro Driver boards
• Real-time coordination of multiple motors
• Supports up to 6 Micro Driver boards (12 motors)

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System Architecture

┌─────────────┐
│  Control PC │
└──────┬──────┘
       │ Ethernet
       │
┌──────▼──────┐      Power Supply (24V)
│ Master Board│◄──────────────────────┐
└──┬──┬──┬──┬─┘                       │
   │  │  │  │ SPI                     │
   │  │  │  └──────────┐              │
   │  │  └──────────┐  │              │
   │  └──────────┐  │  │              │
   │             │  │  │              │
┌──▼───┐ ┌──▼───┐ ┌▼──▼┐ ┌────▼─────┐│
│Micro │ │Micro │ │Micro│ │  Micro   ││
│Driver│ │Driver│ │...  │ │  Driver  ││
└──┬───┘ └──┬───┘ └┬───┘ └────┬─────┘│
   │        │      │          │       │
   │        │      │          │       │
 ┌─▼─┐    ┌─▼─┐  ┌▼─┐      ┌─▼─┐     │
 │M1 │    │M2 │  │..│      │M12│     │
 └───┘    └───┘  └──┘      └───┘     │
                                      │
 └─────────────────────────────────────┘

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Specifications

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External Documentation

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Key Documentation Sections

• Hardware Design: Schematics, PCB layout, and BOM
• Firmware: Real-time control firmware for STM32
• Software Interface: Python SDK and C++ API
• Wiring Documentation: Connection details for Micro Drivers and IMU
• Setup Instructions: Configuration and initialization

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Communication Interfaces

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Ethernet Connection

• Protocol: UDP for low-latency communication
• Control Loop: 1kHz real-time control
• Commands: Motor torques, position/velocity setpoints
• Feedback: Encoder positions, velocities, motor currents

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Ethernet Cable Options

• Standard Cable
• Custom Cable

Use a standard Ethernet cable (Cat5e or better) for most applications.

For integrated robot designs, create a custom 4-wire Ethernet cable:

• Uses 4 of 8 wires (reduced stiffness)
• Requires crimping tool for RJ45 connectors
• Better for cable management in compact robots

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SPI Bus

• Topology: Daisy-chain configuration
• Frequency: 1kHz control loop
• Connectors: 5-pole Hirose DF13
• Wire: 0.14 mm² Kabeltronik wires

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SPI Pin Assignment

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IMU Interface

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IMU Connection

• Connector: 10-pin rectangular connector (ribbon cable)
• Extension: 4-pin Hirose DF13 connector
• Protocol: I2C communication
• Power: 3.3V or 5V (depending on IMU)

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Supported IMUs

• Invensense MPU-6050
• Invensense MPU-9250
• Bosch BMI088
• Other I2C-compatible IMUs

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Power Distribution

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Power Input

• Connector: XT30 power connector
• Voltage: 24V nominal (5V-32V range)
• Wire gauge: 1 mm² Kabeltronik wires

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Power Output

• Distribution: Power supplied to all Micro Drivers
• Connection: Via 2-pin Hirose connector on one Micro Driver
• Daisy-chain: Power distributed between Micro Driver boards

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Power Connector Convention

• Red wire: Positive (+24V)
• Black wire: Ground (GND)

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Robot Interface Wire

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Supply Side (Power Source)

• Wire: 1 mm² Kabeltronik wires
• Connector: 4mm power connectors
• Colors: Red (+24V), Black (GND)

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Robot Side

• Wire: 1 mm² Kabeltronik or custom 4-wire Ethernet cable
• Connector: XT30 power connector
• Additional wires: Optional Ethernet data lines in same cable

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Software Interface

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Python SDK

from master_board_sdk import MasterBoard

# Initialize Master Board
board = MasterBoard()
board.Init()

# Enable motors
for i in range(12):
    board.SetMotorEnabled(i, True)

# Control loop
while True:
    # Read encoder positions
    positions = board.GetPositions()
    
    # Calculate control commands
    torques = controller.compute(positions)
    
    # Send torque commands
    board.SetTorques(torques)
    
    # Send command packet
    board.SendCommand()

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C++ API

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ROS Integration

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Advantages

1. Centralized Control: Single point of communication for complex robots
2. Ethernet Interface: Standard networking hardware and protocols
3. Synchronized Control: 1kHz real-time control of all motors
4. IMU Integration: Built-in support for orientation sensing
5. Scalable: Supports 2-12 motors with identical interface
6. Modular: Easy to add or remove Micro Driver boards

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Use Cases

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Multi-DOF Robots

• Quadruped robots: 8-12 degrees of freedom
• Humanoid robots: 12+ degrees of freedom
• Manipulation systems: Multiple robot arms

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Applications Requiring

• Ethernet-based control
• Centralized coordination
• IMU feedback
• Synchronized multi-motor control
• Professional software interface

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Compatible Robots

• TriFinger v2 and v3: 9 motors (3 Micro Drivers)
• Quadruped 12dof: 12 motors (6 Micro Drivers)
• Solo v2 and v3: 12 motors (6 Micro Drivers)
• Bolt: 12 motors (6 Micro Drivers)
• Custom multi-motor systems

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Getting Started

git clone https://github.com/open-dynamic-robot-initiative/master-board.git
cd master-board
pip install .

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Troubleshooting

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No Ethernet Communication

1. Check network cable connection
2. Verify IP address configuration
3. Check firewall settings on control PC
4. Test with example scripts

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SPI Communication Errors

1. Verify SPI wire connections
2. Check wire length (keep short)
3. Ensure proper power to all boards
4. Check for loose connectors

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Motor Not Responding

1. Verify Micro Driver power
2. Check SPI connection to that specific driver
3. Ensure motor is enabled in software
4. Check LED status on Micro Driver

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Additional Resources

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Resources

• Open Dynamic Robot Initiative Website
• YouTube Channel
• Community Forum
• Research Paper

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License