Nissan Leaf EV-CAN

The EV-CAN network is the main CAN bus used by the donor Nissan Leaf components — the PDM, tractioninverter and BMS — and is the bus the DIY VCM talks to.

Electrical

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

Signalling

EV-CAN uses ISO 11898-1 with 11-bit identifiers and a 500 kbit/s baud rate.

Topology

A well-functioning CAN bus should have a linear topology with short stubs sticking out and a 120 Ω termination at each end. In the Nissan Leaf the following ECUs 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 addition to the CRC built into the CAN frames themselves).

Sequence counter

The sequence counter just counts up from 0 → 3 continuously.

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 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 the PDM and traction inverter pages.

`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 TBD Nm/bit.

Sequence counter: loops 0 → 3.

CRC: see above.

`0x1DA` — Inverter status

Sender: Traction inverter Receiver: VCM Frequency: TBD Hz DLC: 8 bytes