OpenGrab CAN daughterboard (OGCAN) provides CAN interface for OpenGrab EPM. Implemented CAN protocol is UAVCAN. Hardware part of this interface follows the UAVCAN convention (see "Hardware Interconnection"). Generally, OGCAN is the first commercially available piece of hardware that follows the UAVCAN RFC.
OGCAN is an open source/open hardware device. Firmware sources and schematics can be found on the github page: https://github.com/pavel-kirienko/opengrab_can. Build and Flash instructions are also provided.
OGCAN has one physical CAN 2.0 interface (ISO 11898-2, 1 Mbps) with two connectors JST-PA (4 pin). One extra CAN connector allows to connect multiple nodes into a bus without need to use intermediate T-connectors. Both connectors also provide the power supply for the board.
CAN connectors pinout:
Wire - twisted pair
pair 1 tip (white/blue)
pair 1 ring (blue)
pair 2 ring (orange)
pair 2 tip (white/orange)
If the device is last node on the CAN bus, the jumper near the CAN connectors can be closed to terminate the bus with 120 Ohm resistor (see the picture above).
UART connector should be used to configure the device via CLI. Currently, UART is the only interface that allows to configure the device (later the device will support reconfiguration via UAVCAN as well). UART parameters - 115200-8-N-1. Note that CLI will not be available unless the RX pin was pulled up at startup (for safety reasons); that means that the UART cable must be connected before power-up.
Manual control of the EPM control output.
Read the magnet state feedback
Turn the EPM on
Turn the EPM off
Supported standard data structures (data structs that are mandatory for any UAVCAN node are not listed):
OGCAN publishes state of the EPM once a second using uavcan.equipment.hardpoint.Status.
EPM can be controlled using uavcan.equipment.hardpoint.Command.
Supply current (EPM excluded)
CAN maximum bit rate
CAN positive-going input threshold voltage
CAN negative-going input threshold voltage
CAN differential output voltage, dominant
CAN differential output voltage, recessive
UART low level input voltage
UART high level input voltage
UART low level output voltage
UART high level output voltage
Free air temperature
 Connectors are scheduled to be changed to UAVCAN-compliant in the mass production release