Controlled Area Network Board

Controlled Area Network Board

The pattern of H-CAN and L-CAN

A: the pattern starts

B: the pattern finishes

Channel 1 is the H-CAN, because the voltage increase from the base voltage.

Channel 2 is the L-CAN, because the voltage decrease from the base voltage.

The difference between H-CAN and L-CAN base voltage the ECU marks it at 0 in the digital signal and the difference between increased voltage of H-CAN and decreased voltage of L-CAN is 1 in the digital signal. 

The patterns:

Right indicator:

Left indicator:

Rear wiper:

Stoplights:

Fuel pump:

Reverse lights:

In the red square, the different signal gives different commands to the control unit.

The circuit of the board:

Right hand indicator:

input pin #7 -> R5 -> Pin #6 (VP18F258) -> CAN -> IC5 -> Control unit pin #5 -> R32 -> IC9 -> U7 (transistor) -> output pin #5

Rear Wiper:

input pin #9 -> R8 -> Pin #25 (VP18F258) -> CAN -> IC5 -> Control unit pin #10 -> R35 -> U14 (transistor) -> RL4 (Relay) -> output pin #8

Voltage regulators:

U1 7805

input pin #1,2

output: Pin #1 (VP18F258) through R20, Pin #20 (VP18F258), Pin #3 (IC4), Pin #16 (IC3)

U2 7805

input pin #1,2

output: Pin #14 (output control unit)

For stoplight:

when the vehicle wants turn on the stoplights, current go through input pin#5, R3 to the pin #4 of VP18F258 to translate the signal to digital H-CAN signal and L-CAN signal through IC4. The CAN signal goes to IC5 and translate to output control unit. The unit will sent the signal from its pin #3 go through R20 to IC7 to switch on the transistor U5 to closet the circuit and turn on the stoplights from output pin #3.