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(daisy-chain-pcb)=

CAN Bus Daisy Chain PCB

This PCB is designed to connect various different CAN bus conductor pairs to make wiring the bus easier. For terminology and the rationale behind why this is needed, see .

Since it was originally designed for CAN wiring to ESCs, the PCB also includes power distribution in the form of a male XT90 connector to 3x female XT30 connectors.

Configurations

To allow for different uses, the PCB has several jumper pairs which, when bridged, put it into different configurations. The design configurations are listed below.

Configuration Jumpers bridged Main A Main B Multi 1 B
Loop Splitter J9, J10 Multi 1 A Multi 2 A N/C
Splitter with loopback J9, J10, J13, J14 Multi 1 A Multi 2 A Multi 2 A
2x Looping Branch J11, J12, J13, J14 Multi 1 A Multi 2 B Multi 2 A
3x Looping Branch J13, J14 Multi 1 A Multi 3 B Multi 2 A
Main Loopback J7, J8 Main B Main A N/C
Multi 1 Loopback J5, J6 Multi 1 A Multi 3 B Multi 1 A

For completeness, the jumper pairs are as follows:

Jumper 1 Jumper 2 Connection 1 Connection 2
J5 J6 Multi 1 A Multi 1 B
J7 J8 Main A Main B
J9 J10 Multi 2 A Main B
J11 J12 Multi 2 B Main B
J13 J14 Multi 1 B Multi 2 A

And the fixed connections:

Pair 1 Pair 2
Main A Multi 1 A
Main B Multi 3 B
Multi 2 B Multi 3 A

Loop Splitter

This is the configuration for all daisy-chain boards inside the rover, and usually the most useful. It splits a single {term}loop connection (both "A" and "B") into two standard ("A" pair only) connections.

If the optional J13/J14 pair are connected, the J5/J6 pin jumpers can be used to create a convenient loopback across the Main connector.
However, bridging those jumpers _may_ reduce performance by adding {term}`branch` length.
Additionally, if J5/J6 are in use, it would be easy to forget what state they're in, which could cause unexpected behaviour and hard to debug issues.

Connectors

  • Main: Loop
  • Multi 1: Standard
  • Multi 2: Standard
  • Multi 3: N/A

2x Looping Branch

This was used to connect Perseus V1's ESCs on the suspension arm to the CAN bus. Main, Multi 1, and Multi 2 are all loops in this configuration.

Connectors

  • Main: Loop
  • Multi 1: Loop
  • Multi 2: Loop
  • Multi 3: N/A

3x Looping Branch

This configuration has never been used, and was intended to allow for fallback to the Artemis chassis with its 3 wheels (and therefore ESCs) per side. As such, all 4 connectors are loops.

Connectors

  • Main: Loop
  • Multi 1: Loop
  • Multi 2: Loop
  • Multi 3: Loop

Loopback

Intended only to complete a branch's loop. Currently this job is handled by loopback connectors instead and is not needed.

Connectors

  • Main: Loopback
  • Multi 1: N/A
  • Multi 2: N/A
  • Multi 3: N/A

Resources