Introduction
Encompasses all the CAN boards we are making and buying for use in our systems and to cover how we intend on integrating them. To cover software for Ardupilot, hardware (terminations and topology), and placement (mechanical but affects topology).
Custom Projects
Daniel Puratich EE only
Daniel Puratich Meghan Dang leading EE
EFS unassigned
Camron Sabahi-Pourkashani leading EFS
Jerry Tian leading EE
Michael Botros leading EE
EFS unasdigned
Stanley Tang leading EFS
Daniel Puratich Meghan Dang leading EE
EFS unassigned
needs scoping
low priority, cost down only
Useful COTS Information
Useful ICs
MCP2515
TJA1051TK/3,118
COTS Specs
https://docs.px4.io/main/en/assembly/cable_wiring.html
Contains the CAN connector, pin order, twisting, and connector spec we are following
Harness Philosophy
See example system diagram in https://uwarg-docs.atlassian.net/wiki/spaces/EL/pages/2524119043/ESC+CAN+Adapter#Schematic-Wise , but the high level concept is that every board has a CAN input and a CAN output connector (two identical CAN connectors) so that we can daisy chain devices without harness splices. I talked to rocketry and they do CAN harness splices everywhere and it does offer a good amount of board space savings, but custom harnesses suck. MNS does it with two CAN connectors on the PCBA as we intend on doing. Harnesses suck, let’s win on the integration side for our custom projects. See another comment about this here. If CAN splitters are needed see COTS projects like https://holybro.com/products/can-hub or custom projects like https://warg.365.altium.com/designs/A3BFF15E-6855-48FA-B8A6-B31C2041AA33#design . Despite taking up more board space for the connectors, doing this method allows us to minimize the length of the stub required to add another device to the bus. Essentially a harness splice necessitates a longer stub. This doesn't matter for lower CAN data rates we’re working with, but could be nice in the future!
Because our boards have two CAN connectors, we can terminate the end of a bus using external terminations (i.e. https://holybro.com/products/spare-parts-uavcan-micro-termination-plug ).