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Update Canjectors — full 5-variant family documented

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- Start: 1 CAN, 1 12V (bus origin)
- Minor: 3 CAN, 1 12V (intermediate)
- Middle: 3 CAN, 2 12V (intermediate + power)
- Major: 6 CAN, 2 12V (end of chain)
- Endz: 1 CAN, 1 12V + USB diagnostic (start or end)
- All have shunt-activated 120Ω termination
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MrC
2026-05-04 01:48:26 +00:00
parent b8aa72caba
commit 70a5e48ab8
1 changed files with 17 additions and 9 deletions
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sources/2890/canjectors.md
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@@ -52,15 +52,19 @@ The schematic shows the "middle" Canjector variant with:
## Design Variants
Chris designed three Canjector variants for different positions in the CAN bus topology:
Chris designed five Canjector variants to form a complete CAN bus distribution system. All variants support configurable termination via a shunt jumper — populate the shunt to activate 120Ω termination at any position in the chain.
| Variant | Position | CAN Termination | Notes |
|---------|----------|----------------|-------|
| **Start** | Bus origin (PDH side) | No termination at this end | Upstream CAN connector from PDH |
| **Middle** | Intermediate nodes | Switchable 120Ω | 3 CAN connections + 12V passthrough |
| **Major** | Bus terminus (end of line) | Fixed 120Ω termination | Final node — TERM switch, 120Ω resistor populated |
| Variant | CAN connections | 12V outputs | Termination | Typical use |
|---------|----------------|-------------|-------------|-------------|
| **Start** | 1 | 1 | Shunt-activated | Bus origin at PDH |
| **Minor** | 3 | 1 | Shunt-activated | Intermediate node |
| **Middle** | 3 | 2 | Shunt-activated | Intermediate node + power distribution |
| **Major** | 6 | 2 | Shunt-activated | End of chain (large node) |
| **Endz** | 1 | 1 | Shunt-activated | Start OR final terminator — diagnostic USB interface |
**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.
**All Canjectors share the same termination philosophy:** no fixed termination at any position. Use a shunt jumper to enable 120Ω termination exactly where the bus physics require it. This eliminates the need for separate "terminating" and "non-terminating" variants.
**Endz** is unique — it's the diagnostic variant with a USB Type-B connector for direct laptop-to-CAN connection. Meant to serve as either the first or last device in the chain. Currently experiencing design problems; no working units on hand.
## Connection to Training
@@ -84,6 +88,10 @@ This is a **confidence builder** for the training vault — it shows Chris's pra
|------|-------------|
| `canjector-schematic.png` | Middle Canjector — EasyEDA schematic |
| `canjector-start-pcb.png` | Start variant — PCB layout (red solder mask) |
| `canjector-major-render.png` | Major variant — 3D render, blue PCB |
| `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 |
| `canjectors.md` | This documentation file |
| `canjector-gerbers/` | Manufacturing files (Gerbers + drill files + How-to-order guide) |
| `canjector-gerbers/` | Major variant manufacturing files |
| `canjector-minor-gerbers/` | Minor variant manufacturing files |
| `canjector-endz-gerbers/` | Endz variant manufacturing files |