CANivore® API

All device constructors have an overload that takes a CANBus object (Java, C++, Python). The native roboRIO CAN bus can be constructed using CANBus.roboRIO(). Otherwise, the CANBus constructor takes a string identifier. This identifier can be * to select the first available CANivore®, or it can be the CANivore® name or serial number. On non-FRC Linux systems, this string can also be a SocketCAN interface.

Note

If there are multiple CANivore® devices with the same name, the system will use the first CANivore® found.

If no CAN bus string is passed into the constructor, or the CAN bus string is empty, the behavior is platform-dependent:

• roboRIO: use the roboRIO native CAN bus

• Windows: use the first CANivore® found

• non-FRC Linux: use SocketCAN interface can0

Java

final TalonFX fx_default = new TalonFX(0); // On roboRIO, this constructs a TalonFX on the RIO native CAN bus
final TalonFX fx_rio = new TalonFX(1, CANBus.roboRIO()); // This also constructs a TalonFX on the RIO native CAN bus
final TalonFX fx_drivebase = new TalonFX(0, new CANBus("Drivebase")); // This constructs a TalonFX on the CANivore bus named "Drivebase"
final CANcoder cc_elevator = new CANcoder(0, new CANBus("Elevator")); // This constructs a CANcoder on the CANivore bus named "Elevator"

C++ (Header)

hardware::TalonFX fx_default{0}; // On roboRIO, this constructs a TalonFX on the RIO native CAN bus
hardware::TalonFX fx_rio{1, CANBus::RoboRIO()}; // This also constructs a TalonFX on the RIO native CAN bus
hardware::TalonFX fx_drivebase{0, CANBus{"Drivebase"}}; // This constructs a TalonFX on the CANivore bus named "Drivebase"
hardware::CANcoder cc_elevator{0, CANBus{"Elevator"}}; // This constructs a CANcoder on the CANivore bus named "Elevator"

Python

self._fx_default = hardware.TalonFX(0) # On roboRIO, this constructs a TalonFX on the RIO native CAN bus
self._fx_rio = hardware.TalonFX(1, CANBus.roborio()) # This also constructs a TalonFX on the RIO native CAN bus
self._fx_drivebase = hardware.TalonFX(0, CANBus("Drivebase")) # This constructs a TalonFX on the CANivore bus named "Drivebase"
self._cc_elevator = hardware.CANcoder(0, CANBus("Elevator")) # This constructs a CANcoder on the CANivore bus named "Elevator"

The CANBus API can also be used to retrieve information about any given CAN bus, such as the bus utilization.

Java

// create a CAN bus for the CANivore named drivetrain
final CANBus canbus = new CANBus("drivetrain");
// construct a TalonFX on the CAN bus
final TalonFX fx = new TalonFX(0, canbus);

// retrieve bus utilization for the CAN bus
CANBusStatus canInfo = canbus.getStatus();
float busUtil = canInfo.BusUtilization;

if (busUtil > 0.8) {
   System.out.println("CAN bus utilization is greater than 80%!");
}

C++

// create a CAN bus for the CANivore named drivetrain
CANBus canbus{"drivetrain"};
// construct a TalonFX on the CAN bus
hardware::TalonFX fx{0, canbus};

// retrieve bus utilization for the CANivore named drivetrain
CANBus::CANBusStatus canInfo = canbus.GetStatus();
float busUtil = canInfo.BusUtilization;

if (busUtil > 0.8) {
   std::cout << "CAN bus utilization is greater than 80%!" << std::endl;
}

Python

# create a CAN bus for the CANivore named drivetrain
self._canbus = CANBus("drivetrain")
# construct a TalonFX on the CAN bus
self._fx = hardware.TalonFX(0, self._canbus)

# retrieve bus utilization for the CANivore named drivetrain
can_info = self._canbus.get_status()
bus_util = can_info.bus_utilization

if bus_util > 0.8:
   print("CAN bus utilization is greater than 80%!")

CANivore® Status Prints

When working with CANivore® CAN buses in a robot program, Phoenix prints some messages to report the state of the CANivore® connection. These messages can be useful to debug connection issues (bad USB vs bad CAN) or report bugs to CTR Electronics.

Connection Messages

Message	Connection Status
CANbus Failed to Connect	Could not connect to a CANivore® with the given name or serial number
CANbus Connected	Successfully found and connected to the CANivore® with the given name or serial number
CANbus Disconnected	Detected that a CANivore® USB device has been disconnected

CANivore® Bring-up Messages (Linux only)

Message	Bring-up Status
CANbus Failed Bring-up	Found and connected to the CANivore®, but could not configure the device or start the network
CANbus Successfully Started	Successfully configured the CANivore® and started the network

Network State Messages

Message	Network State
CANbus Network Down	Linux: The SocketCAN network has been deactivated, USB-to-CAN activity has stopped Windows: Could not open the communication channels for USB-to-CAN traffic
CANbus Network Up	Linux: The SocketCAN network has been activated, USB-to-CAN activity has resumed Windows: Successfully opened the communication channels for USB-to-CAN traffic