Appearance
The hardware
Two generations of the box exist. They run the same applications, look alike from the bus and behave alike at installation; they differ in their internal pinout and in their hardware ID.
| CanCan v1 | CanCan v2 | |
|---|---|---|
| Board name | muxen_cancan | muxen_cancan_v2 |
| Hardware ID | 990010047 | 990010061 |
| Microcontroller | STM32L496RG @ 80 MHz | same |
| CAN 1 — MUXEN bus | 500 kbit/s | 500 kbit/s |
| CAN 2 — equipment bus | bitrate set by the application | same |
| Relay outputs | 2 | 2 |
| Dry-contact inputs | 2 | 2 |
| Analog inputs | 2 | 2 |
| Sensor supply | switched (EnAnalogPwr) | same |
Nothing about the wiring or the commissioning changes between the two. A v2 fitted in place of a v1 with the same settings behaves the same way.
EnCanAuxPwr. This parameter appears in the table of most applications and is a leftover: it drives a signal that shipped CanCan boards do not use. Leave it at 0. It is not part of any commissioning procedure, and it is never the reason an equipment bus is silent.
The two CAN buses
| Side | Speed | Termination | |
|---|---|---|---|
| CAN 1 | the boat's MUXEN bus | 500 kbit/s, fixed | the MUXEN bus is terminated at its two physical ends — not at the CanCan unless the CanCan is an end |
| CAN 2 | the third-party equipment | depends on the application — see its manual | the equipment bus is terminated at its two ends by the same rule |
Both buses are ordinary 120 Ω CAN: two wires plus a common ground, 120 Ω at each end of each segment and nowhere else. A bus with one termination too many or one too few may work on the bench with a short cable and fail on the boat; it is worth checking with an ohmmeter (60 Ω across a powered-down, correctly terminated bus).
The two buses are electrically separate. A CanCan does not pass frames from one bus to the other unless its application does so deliberately — that is exactly what its application is for.
Inputs and outputs
Every application exposes these, whatever else it does:
| Count | What it is | |
|---|---|---|
| Relay outputs | 2 | dry contacts, commanded from the MUXEN bus |
| Dry-contact inputs | 2 | closed to ground = active; internal pull-up, no external resistor needed |
| Analog inputs | 2 | measured in millivolts, 0–5.5 V range |
| Sensor supply | 1 | a switched supply for the analog sensors, on by default (EnAnalogPwr = 1) |
| System LED | 1 | the local diagnostic — see Common mistakes |
The analog inputs are published as raw millivolts. Turning them into litres, degrees or bars is the Brain's job, not the box's.
Power and mounting
The box is powered from the boat's DC distribution. Follow the mechanical and electrical figures on the product data brief for the product ID you are installing — this manual describes behaviour, not ratings.
Firmware compatibility
A firmware image is built for one product ID and one hardware generation, and the two generations are signed with different keys. A v1 image pushed at a v2 box is refused by the box itself, before anything is written — the upload fails, the box keeps running.
The software version tells you the generation at a glance: 5.x images are for CanCan v1, 6.x images for CanCan v2. See Loading and updating a firmware.