After experiencing **critical CAN bus failures** during competition, Chris designed the Canjector system as a robust interconnect solution for Team 2890's robot. Modeled after the SWYFT CANnect concept but with custom design work, Canjectors provide reliable CAN + power distribution at all critical connections.
The design philosophy: prevent wiring failures from killing the robot mid-match.
## Design Basis
Chris studied the **SWYFT CANnect** system as inspiration:
- Run CAN bus + 12V power over standardized cabling
- Easy connector system (WAGO lever terminals)
- Built-in CAN termination options
- Robust form factor
Canjectors go further with custom modifications for Team 2890's specific failure points.
## Current Design: Middle Canjector
The schematic shows the "middle" Canjector variant with:
- **12V power** passthrough
- **3 CAN connections** (RJ45 connectors)
- **WAGO terminal blocks** for clean wiring (2601-1104 series)
- **120Ω termination resistor** (R4) between CAN signal lines — switchable
- **Power indicator LED** (green, 0603) with 470Ω current limiting resistor
- **2-pin header** for additional configuration
## Key Features
- **Dual CAN paths** — each Canjector bridges multiple CAN segments
- **Integrated termination** — 120Ω resistor switchable per segment
- **Power LED** — visual confirmation that 12V is present
- **RJ45 connectors** — industry standard, easy to cable, robust
**Major variant:** Blue PCB, three identical sections, TERM label, 120Ω termination resistor visible, PWR LED, 2-pin header. This is the end-of-bus variant — fixed 120Ω termination resistor must be populated. Zip file in `canjector-gerbers/` directory.
**For students:** CAN bus failures are among the most frustrating problems in FRC — a loose wire or failed connector kills the whole bus. The Canjector system teaches:
- **Redundancy** — when one path fails, traffic routes around it
- **Termination** — 120Ω at each end of the bus, switchable at intermediate nodes
- **Visual debugging** — power LEDs let you confirm connectivity at a glance
- **Modular design** — if one Canjector fails, replace it in minutes
## Why This Matters
Chris experienced critical CAN failures at competition. The Canjector system is a direct response — solving the failure mode with custom hardware instead of hoping the stock connectors hold. This is the kind of real-world engineering that separates good teams from great ones.
This is a **confidence builder** for the training vault — it shows Chris's practical engineering under pressure. Good story for students: identify the problem, study existing solutions, design your own, build it, test it. The full engineering cycle, not just code.
