Changes

The CAN Terminating Impedance Connector, a 2x4 male terminal strip, is used for the purpose of applying the necessary 120-ohm terminating impedance on each end of the CAN bus. Since the current HONEY architecture dictates that the Core Avionics and Core BMS occupy the top and bottom positions in the stack, they are currently the only boards to utilize this connector. However, as the architecture may evolve, and positions of boards change, it is necessary to implement this connector so that your board may effectively institute the necessary terminating impedance.

The CAN Terminating Impedance Connector, a 2x4 male terminal strip, is used for the purpose of applying the necessary 120-ohm terminating impedance on each end of the CAN bus. Since the current HONEY architecture dictates that the Core Avionics and Core BMS occupy the top and bottom positions in the stack, they are currently the only boards to utilize this connector. However, as the architecture may evolve, and positions of boards change, it is necessary to implement this connector so that your board may effectively institute the necessary terminating impedance.

[[File:can_stack.jpg | right| thumb | <center> CAN Stack Implementation </center>]]

[[File:can_stack.JPG | right| thumb | <center> CAN Stack Implementation </center>]]

[[File:can_wires.jpg | right| thumb | <center> CAN Feed-through </center>]]

[[File:can_wires.JPG | right| thumb | <center> CAN Feed-through </center>]]

A CAN bus requires a 120 ohm resistor between CAN HIGH and CAN LOW for the first and last devices on the bus to prevent reflections. This is achieved by jumping two pins, with a resistor in between. In this case, for CAN1, this is achieved by the top two pins in this connector. 1_TERM_1 and 1_TERM_2 are open-circuit, but, when jumped, become closed. 1_TERM_2 is connected to CAN1_L. 1_TERM_1 is connected to one end of a 120 ohm resistor -- the other end of the resistor is connected to CAN1_H. Thereby, by placing a jumper on the two pins and closing the circuit, a 120 ohm impedance is effectively engaged, properly terminating the bus. The same is true for pins 3/4, which are for CAN2 (not used by most boards). Pins 4-8 exist solely as a position to place jumpers when they are not used by a board -- IE when the board is not implementing the terminating impedance.  

A CAN bus requires a 120 ohm resistor between CAN HIGH and CAN LOW for the first and last devices on the bus to prevent reflections. This is achieved by jumping two pins, with a resistor in between. In this case, for CAN1, this is achieved by the top two pins in this connector. 1_TERM_1 and 1_TERM_2 are open-circuit, but, when jumped, become closed. 1_TERM_2 is connected to CAN1_L. 1_TERM_1 is connected to one end of a 120 ohm resistor -- the other end of the resistor is connected to CAN1_H. Thereby, by placing a jumper on the two pins and closing the circuit, a 120 ohm impedance is effectively engaged, properly terminating the bus. The same is true for pins 3/4, which are for CAN2 (not used by most boards). Pins 4-8 exist solely as a position to place jumpers when they are not used by a board -- IE when the board is not implementing the terminating impedance.