Professional UAVs are usually complex systems which require a reliable communication with its control units. In the case of multirotors the large amount of motors to be controlled must be addressed somehow.
Usually, pulse width (PWM) and serial (RS232, RS485) channels are used in UAVs to control, command and retrieve telemetry data from these subsystems.
PWMs are not well suited for big distances, turning even worse in noisy conditions. In addition, some systems requires serial communications to send commands and receive telemetry, which complicates wiring as we add more controllers to the platform.
Sometimes is not even possible to directly connect to all the subsystems because the amount of available ports is limited.
Embention’s engineers have come to a simple yet efficient and reliable solution for all those issues: Embention CAN expander board.
This board provides dual redundant CAN channels for the Autopilot/System side interface. In the other side, it provides PWMs, UARTs and Digital I/O to connect to ESCs, servos, controls units, etc.
Benefits of the CAN Expander
CAN Expander provide, with just two CAN wires (or four if redundant CAN is wanted), a way to interconnect a big amount of systems at long distance with the proven reliability of the CAN bus. We convert a star connection scheme to a bus connection scheme. This reduces the total wire length and obviously the wiring weight, which is often critical issue in any flying platform.
Finally, it also supports dual redundant CAN. If one of the busses gets broken, the other will continue working normally, adding the extra safety required in nowadays systems.
The amount of systems that can be attached depends on the data load. A system with 16 boards controlling motors at 50Hz and sending telemetry from them at 1Hz has been implemented successfully in a real case.