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Simplify Canjectors to 3 variants: Endz, Minor, Major

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Endz: 1 CAN, 1 12V, origin
Minor: 3 CAN, 1 12V, single wheel (CANcoder + 2 motors)
Major: 6 CAN, 2 12V, heavy distribution
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MrC
2026-05-04 01:53:41 +00:00
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@@ -22,30 +22,10 @@ After experiencing **critical CAN bus failures** during competition, Chris desig
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
- **Modular CAN distribution** — one board per functional zone
- **Integrated termination** — 120Ω resistor switchable via shunt jumper at any position
- **Power LED** — visual confirmation that 12V is present
- **RJ45 connectors** — industry standard, easy to cable, robust
- **WAGO 2601 series** — tool-free, reliable terminal connections
@@ -53,30 +33,24 @@ The schematic shows the "middle" Canjector variant with:
## Design Variants
Chris designed five Canjector variants. **Names are printed on the physical PCBs** — Endz, Major, Minor are the actual designations.
Three Canjector variants. **Names are printed on the physical PCBs.**
All variants support configurable termination via a shunt jumper — populate the shunt to activate 120Ω termination anywhere in the chain.
| PCB Name | CAN ports | 12V outs | Primary role |
|----------|-----------|----------|-------------|
| **Start** | 1 | 1 | Bus origin at PDH side |
| **Minor** | 3 | 1 | Single wheel module — CANcoder + 2 motors |
| **Middle** | 3 | 2 | Mid-chain node + power distribution |
| PCB Name | CAN ports | 12V outs | Role |
|----------|-----------|----------|------|
| **Endz** | 1 | 1 | Origin — first device in chain, PDH side |
| **Minor** | 3 | 1 | Mid-chain — single wheel (CANcoder + 2 motors) |
| **Major** | 6 | 2 | Heavy distribution — end of main runs |
| **Endz** | 1 | 1 | USB diagnostic tap — serves as first OR last device in chain |
**Minor — single wheel module design:**
### Minor — Single Wheel Module
One Minor per swerve corner:
- 1 CANcoder (CTR Electronics CAN FD magnetic encoder for steering feedback)
- 2 motors (typically drive motor + steering motor, or drive + mechanism)
- 2 motors (drive + steering per MK4i)
- 1 12V output for accessories
Minor was designed for MK4i swerve modules — one Minor per wheel handles the CAN bus connections for the encoder and both motors. Clean single-point connection for each corner of the robot.
**Note on overlap:**
- Start and Endz both serve end-of-chain positions (first or last device)
- Minor and Middle both have 3 CAN ports — Middle adds a second 12V output for power distribution
All Canjectors use the same shunt-activation scheme for 120Ω termination. This means any variant can terminate the bus when needed.
Clean single-point connection per wheel — troubleshooting localizes to one module per corner.
## Connection to Training
@@ -90,20 +64,16 @@ All Canjectors use the same shunt-activation scheme for 120Ω termination. This
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.
## Notes for MrC
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.
## Files
| File | Description |
|------|-------------|
| `canjector-schematic.png` | Middle Canjector — EasyEDA schematic |
| `canjector-start-pcb.png` | Start variant — PCB layout (red solder mask) |
| `canjector-schematic.png` | Minor variant — EasyEDA schematic |
| `canjector-start-pcb.png` | Endz variant — PCB layout |
| `canjector-minor-render.png` | Minor variant — 3D render, blue PCB |
| `canjector-major-render.png` | Major variant — 3D render, blue PCB, 6 CAN ports |
| `canjector-endz-render.png` | Endz variant — USB-to-CAN diagnostic interface |
| `canjector-major-render.png` | Major variant — 3D render, blue PCB |
| `canjector-endz-render.png` | Endz variant — USB-to-CAN diagnostic |
| `canjectors.md` | This documentation file |
| `canjector-gerbers/` | Major variant manufacturing files |
| `canjector-minor-gerbers/` | Minor variant manufacturing files |
| `canjector-endz-gerbers/` | Endz variant manufacturing files |
| `canjector-endz-gerbers/` | Endz variant manufacturing files |