Hardware — Motors, Power & Boards
Raspberry Pi (companion computer), Arduino Mega/Uno (real-time controllers), PCA9685 boards for PWM, and dedicated buck converters for stable servo rails — a pro mechatronics stack.
View BOM & WiringCore Hardware Components
Physical Architecture Diagram
Battery (12V)
↓
Power Distribution Board (PDB)
↓
Buck Upper
6.2V @ 20A
↔
Buck Lower
6.5V @ 20A
↓
Pi (5V reg)
PCA + Servos
Arduinos
Separate power rails prevent voltage sag during high-current servo movements. Each rail is independently fused and regulated. Common ground connects all systems securely.
PCA Channel Mapping & CSV
| module_id | i2c_addr | channel | joint_name | servo_type |
|---|---|---|---|---|
| pca1 | 0x40 | 0 | Right_Shoulder_Pitch | DS3218 20kg |
| pca1 | 0x40 | 1 | Right_Shoulder_Roll | DS3218 20kg |
| pca2 | 0x41 | 0 | Right_Hip_Pitch | RDS 25KG |
| pca2 | 0x41 | 1 | Right_Hip_Roll | RDS 25KG |
This CSV is used by both the web UI and motor gateway to validate joint angles and map software commands to hardware channels. Frontend validates against min/max ranges; backend enforces safety checks.
Wiring & Connectors
Raspberry Pi GPIO Usage
GPIO 2 (SDA) & GPIO 3 (SCL)
I²C bus for PCA9685 chain
UART /dev/serial0
Serial link to Arduino Mega (115200/230400 baud)
GPIO 17 (E-STOP)
Hardware emergency stop input (active high)
CSI Ribbon Port
Camera module (keep away from high-current runs)
Safety & Testing Checklist
- 1.Visual Inspection — Check connectors, polarity, wiring labels
- 2.Continuity Test — Verify PDB → buck → rails → PCA V+ paths
- 3.No-Load Power Test — Apply battery; verify 5V Pi rail and buck outputs
- 4.Servo Rail Test — Apply buck output; confirm voltage stability and fuse integrity
- 5.Single-Servo Test — Command neutral position per joint; check torque and smoothness
- 6.Multi-Servo Stress — Run typical gesture set; monitor voltage & current (expect <20A)
- 7.Thermal Test — 15–30 min continuous motion; monitor buck & servo temps
- 8.Heartbeat Fail Test — Cut Pi heartbeat; verify Arduino enters safe mode
- 9.Brownout Test — Simulate battery drop; verify graceful shutdown behavior
- 10.Final Verification — Full demo sequence; confirm no jitter, no resets
Software Coordination
Hardware motion is orchestrated by software. For details on the motor gateway service and how it translates gestures to servo commands, see the Software page.
To understand system-level safety and power coordination, visit the Integrated page.