Wiring and Connections
This guide covers all wiring and connection details for the Open Robot Actuator Hardware electronics system.Actuator Module Wiring
Interface Overview
Each actuator module has two types of electrical connections:- Encoder wire: 5-pole Hirose DF13 connector
- Motor phase wires: 3 wires with 2mm Reely gold connectors
Encoder Wire Specification
- Wire gauge: 0.14 mm² Kabeltronik wires
- Connector: 5-pole Hirose DF13 socket (housing)
- Crimp terminals: Hirose DF13 crimp terminals
- Crimp tool: Hirose DF13 crimp tool
Motor Phase Wire Specification
- Wire gauge: 0.50 mm² Kabeltronik wires
- Connector: 2mm Reely gold connectors (bullet connectors)
- Number of wires: 3 (phase A, B, C)
Wire Length Measurement
Wire length is measured from the surface where the wires exit the shell to the connector interface.
Encoder Pin Assignment
Color Code and Pin Assignment:
| Pin | Color | Signal | Description |
|---|---|---|---|
| 1 | Black | GND | Ground |
| 2 | Red | VCC | Power (5V) |
| 3 | Yellow | A | Encoder channel A |
| 4 | Green | B | Encoder channel B |
| 5 | Blue | I | Index signal |
Alternative: Ribbon Cable
For prototyping, ribbon cables can be used instead of individual wires.
Micro Driver Board Wiring
Connection Types
- Motor phase wires: Right angle pin headers with 0.50 mm² wires
- Power supply: Right angle pin headers with 0.50 mm² wires and XT30 connectors
- Encoder connections: 5-pole Hirose DF13 connectors
- SPI connections: 5-pole Hirose DF13 connectors
Wire Length Measurement
Wire length is measured from the edge of the electronics board to the connector interface.
Power Connector Convention
XT30 Connector Standard:
- Red wire/connector: Positive (+24V)
- Black wire/connector: Ground (GND)
- Male connector: On supply/source side
- Female connector: On load/device side
Components
- Motor phase wires: 0.50 mm² Kabeltronik wires
- Motor phase connectors: 2mm Reely gold connectors
- Power wires: 0.50 mm² Kabeltronik wires
- Power connectors: XT30 connectors
- Pin headers: Right angle, 2.54mm pitch
SPI Wiring
SPI wires connect the Master Board to the Micro Driver boards for real-time communication.
Specifications
- Wire gauge: 0.14 mm² Kabeltronik wires
- Connectors: 5-pole Hirose DF13 sockets on both ends
- Crimp terminals: Hirose DF13 crimp terminals
- Crimp tool: Hirose DF13 crimp tool
SPI Bus Topology
Configuration:
- Daisy-chain connection from Master Board to all Micro Drivers
- Each Micro Driver has input and output SPI connectors
- Last board in chain may need termination
SPI Pin Assignment
| Pin | Color | Signal | Description |
|---|---|---|---|
| 1 | Black | GND | Ground |
| 2 | Red | CLK | Clock signal |
| 3 | Yellow | MOSI | Master Out, Slave In |
| 4 | Green | MISO | Master In, Slave Out |
| 5 | Blue | CS | Chip Select |
IMU Wire
The IMU (Inertial Measurement Unit) connects to the Master Board for measuring robot orientation and acceleration.
Components
- Ribbon cable: 10-pin rectangular connector
- Extension wires: 4-pin Hirose DF13 connector
- Protocol: I2C communication
Pin Assignment
Detailed pin assignment is documented in the Master Board Wiring Documentation.Robot Interface Wire
The robot interface wire provides a single cable for both power and optionally communication to the robot.Supply Side
Components:
- Wire gauge: 1 mm² Kabeltronik wires
- Connector: 4mm power connectors (banana plugs)
- Colors: Red (+24V), Black (GND)
Robot Side
Components:
- Wire gauge: 1 mm² Kabeltronik wires
- Power connector: XT30 connector
- Colors: Red (+24V), Black (GND)
Custom Ethernet Cable Option
For integrated robots, a custom 4-wire Ethernet cable can combine power and data:
Advantages:
- Reduced diameter and stiffness
- Combined power and Ethernet in single cable
- Better cable management
- Ethernet connectors: RJ45 connectors
- Crimp tool: Ethernet crimp tool
- Wire allocation: 2 wires for power, 2 wires for Ethernet data
| Pin | Wire Color | Function |
|---|---|---|
| 1 | Orange/White | Data + |
| 2 | Orange | Data - |
| 3 | Green/White | Power + (24V) |
| 6 | Green | Power - (GND) |
The ethernet connectors are identical on both sides. You can use a standard Ethernet cable instead of a custom one.
TI Launchpad Encoder Wiring
When using TI Evaluation Boards, encoders can be wired using ribbon cables for prototyping.
QEP Port Assignment
- QEP_A: Encoder for motor on booster pack position 1
- QEP_B: Encoder for motor on booster pack position 2
CAN Connector Wiring
For communication with Texas Instruments Evaluation Boards via CAN bus.
Components
- Wire: 2-pole twisted pair
- Connector: 9-pin D-sub connector (male)
- CAN card: PEAK PCI Express CAN card (or similar)
Pin Assignment
| Pin | Signal | Description |
|---|---|---|
| 2 | CAN_L | CAN bus low |
| 3 | GND | Ground |
| 7 | CAN_H | CAN bus high |
CAN Hardware
Recommended CAN card:
- PEAK PCI Express CAN card (dual channel)
- USB CAN adapters also compatible
Foot Sensor Wiring
For robots with foot contact sensors (quadruped, biped robots).
Connection
- Force-sensitive resistors or contact switches
- Connected to analog inputs on Master Board or microcontroller
- Wire through leg structure to electronics
Wire Management
Braided Cable Sleeve
Use braided expandable sleeve for wire protection and organization:
- Protects wires from abrasion
- Improves cable appearance
- Allows bundle expansion for connectors
- Available in various diameters
Heat Shrink Tubing
Apply heat shrink tubing for:
- Strain relief at connectors
- Wire bundling
- Insulation protection
- Professional appearance
Label Maker
Use a label maker with heat shrink labels for:
- Motor phase identification (A, B, C)
- Wire function labeling
- Board identification
- Professional documentation
Crimping Techniques
Hirose DF13 Crimping
Tools required:
- Hirose DF13 crimp tool
- Wire strippers (0.14 mm² wire)
- Flush cutters
Process:
- Strip 2-3mm of insulation from wire
- Insert wire into crimp terminal
- Position in crimp tool (correct cavity)
- Compress firmly to crimp
- Verify mechanical connection (pull test)
- Insert crimped terminal into housing
Tip: Pre-crimped Hirose wires are available from some suppliers, eliminating the need for crimping.
Ethernet Connector Crimping
For crimping RJ45 connectors on custom Ethernet cables:
- Strip outer jacket (25mm)
- Arrange wires according to pin assignment
- Trim wires to equal length
- Insert into RJ45 connector
- Ensure wires reach end of connector
- Crimp with RJ45 crimp tool
- Test continuity
Component Reference
Connectors
| Component | Type | Ordering Information |
|---|---|---|
| Hirose DF13 Socket 5-pin | Housing | DigiKey H2179-ND |
| Hirose DF13 Straight Header 5-pin | Pin header | DigiKey H2202-ND |
| Hirose DF13 Right Angle Header 5-pin | Pin header | DigiKey H11614-ND |
| Hirose DF13 Crimp Terminals | Crimp | DigiKey H9992CT-ND |
| XT30 Connector Pair | Power | HobbyKing, Amazon |
| 2mm Gold Connector | Motor phase | Conrad 1373994 |
| RJ45 Connector | Ethernet | Various suppliers |
| 9-pin D-sub Male | CAN | Various suppliers |
Wire
| Component | Type | Ordering Information |
|---|---|---|
| Kabeltronik 0.14 mm² | Encoder/SPI | Conrad, RS Components |
| Kabeltronik 0.50 mm² | Motor phase/power | Conrad, RS Components |
| Kabeltronik 1 mm² | Main power | Conrad, RS Components |
| Ribbon Cable 1.27mm pitch | Prototyping | DigiKey, Mouser |
Tools
| Tool | Purpose | Ordering Information |
|---|---|---|
| Hirose Crimp Tool | DF13 crimping | Digi-Key H2177-ND |
| Ethernet Crimp Tool | RJ45 crimping | Various suppliers |
| Wire Strippers | Wire preparation | Hardware stores |
| Heat Gun | Heat shrink | Hardware stores |
| Multimeter | Continuity testing | Electronics suppliers |
Testing and Verification
Continuity Testing
After wiring, always verify connections:
- Visual inspection: Check all crimp connections
- Continuity test: Verify electrical connection between ends
- Insulation test: Ensure no shorts between wires
- Pull test: Gently pull on wires to verify mechanical connection
- Power test: Apply power and measure voltages before connecting motors
Common Issues
No encoder signal
No encoder signal
- Check power (5V) to encoder
- Verify pin assignment (A, B channels)
- Test continuity of all 5 wires
- Check Hirose connector seating
Motor not spinning
Motor not spinning
- Verify 3 motor phase connections
- Check phase wire order (try swapping two phases)
- Measure motor phase resistance (should be low, ~1Ω)
- Check for shorts between phases
SPI communication errors
SPI communication errors
- Verify all 5 SPI wires connected
- Check wire length (should be short)
- Ensure proper grounding
- Test with known-good wire
Power issues
Power issues
- Verify polarity (red=+, black=GND)
- Check voltage at each board
- Measure voltage drop under load
- Ensure adequate wire gauge for current
Safety Considerations
Best Practices
- Plan wire routing before cutting wires to length
- Label all wires during assembly
- Use consistent color coding throughout the robot
- Apply strain relief at all connectors
- Keep SPI/encoder wires away from motor power wires
- Document custom wiring for future maintenance
- Test each subsystem before final integration
- Use wire management (braided sleeve, zip ties) for professional results
Resources
- Open Dynamic Robot Initiative Website
- YouTube Channel
- Community Forum
- Research Paper
- Electronic Components Details