openclaw-wiki/sources/2890/canjectors.md

---
title: "Canjectors — Chris's Custom CAN Bus Interconnect System"
tags:
  - hardware
  - electrical
  - can-bus
  - 2890
  - custom
type: hardware-spec
owner: 2890
status: active
sources:
  - "https://swyftrobotics.com/products/swyft-cannect-wiring-system"
  - "https://store.ctr-electronics.com/products/cancoder"
---

# Canjectors — Custom CAN Bus Interconnect System

## Overview

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.

## Key Features

- **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
- **Designed in EasyEDA** — schematic dated 2026-04-09

## Design Variants

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 | 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 |

### Minor — Single Wheel Module

One Minor per swerve corner:
- 1 CANcoder (CTR Electronics CAN FD magnetic encoder for steering feedback)
- 2 motors (drive + steering per MK4i)
- 1 12V output for accessories

Clean single-point connection per wheel — troubleshooting localizes to one module per corner.

## Connection to Training

**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.

## Files

| File | Description |
|------|-------------|
| `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 |
| `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 |