Nissan Leaf EV-CAN

EV-CAN network

The EV-CAN network

Electrical

As any CAN-bus the EV-CAN network uses a twisted pair for differential signaling to improve noise immunity.

Signalling

EV-CAN uses ISO 11898-1 with 11-bit identifiers and 500 kbit/s baudrate

Topology

A well functioning CAN-bus should have a linear topology with short stubs sticking out and a 120 ohm termination in each end. In the Nissan Leaf the following ECU’s are connected on the EV-CAN:

ECU	Termination
VCM	TBD
Traction Inverter	TBD
BMS	TBD
TBD	TBD

Data integrity

Some critical frames are protected with both sequence counters and a CRC checksum (in additional to the CRC build into the CAN-frames).

Sequence counter

The sequence counter just counts up from 0 -> 3 continously

CRC Checksum

There is a specific Nissan CRC calculation of the first 7 bytes of the can-frame stored in the 8th byte, it is just a standard CRC8 calculation with the initial value 0x00 and the polynomial 0x85

fn nissan_crc<const N: usize>(data: &[u8; N]) -> u8 {
    const POLYNOMIAL: u8 = 0x85;
    let mut crc = 0;

    for b in data {
        for i in (0..8).rev() {
            crc <<= 1;
            crc = if (b & (1 << i)) != 0 { crc | 0x01 } else {crc & 0xFE };
            if crc & 0x80 != 0 {
                crc ^= POLYNOMIAL;
            }
        }
    }

    crc
}

Messages

Here are the messages seen on the EV-CAN network for more ECU specific information see:

• PDM
• Traction inverter

0x1d4 - Torque request

Sender: VCM Receiver: Traction Inverter Frequency: 100 Hz DLC: 8 Bytes

Data:

Byte 0	Byte 1	Byte 2	Byte 3	Byte 4	Byte 5	Byte 6	Byte 7
???	???	Torque MSB	Torque LSB	Seq. Counter	???	???	CRC

Torque: signed i16, positive -> accelerate, negative -> regen. Scale ?? Nm/bit

Sequence counter: loop 0 -> 3

CRC: See above…

0x1da - Inverter status

Sender: Traction inverter Receiver: VCM Frequency: ?? Hz DLC: 8 Bytes

Data:

Byte 0	Byte 1	Byte 2	Byte 3	Byte 4	Byte 5	Byte 6	Byte 7
DC voltage MSB	DC voltage LSB	???	???	???	???	???	???

DC voltage: unsigned u16, Scale 0.5 V/bit

References

• Reverse engineering 8Dromeda
• GitHub Repository leaf_can_bus_messages