SANPO USB to CAN

The SANPO USB to CAN protocol controls CAN devices from Windows or Linux and forwards CAN data without requiring an additional driver. The raw CAN frame is wrapped with a SANPO header and trailer for transmission over the USB management serial port. These extra bytes are used only by the board; the CAN device receives the raw CAN frame without a SANPO header or trailer.

For SANPO USB to CAN FD, see SANPO USB to FDCAN.

Connection

After connecting the board over USB, six USB serial ports appear. Two management ports carry this protocol; Windows normally displays them as SANPO Studio Management Port. One management port accesses CAN-1/2 and the other accesses CAN-3/4. The other four ports are independent RS485 serial ports. COM and /dev/ttyACM* numbering is not guaranteed to follow the board silkscreen; initially connect only one CAN device to confirm the mapping.

On Linux, you can run the Python serial-port identification example to identify the two management ports.

Automatically Configure All CAN Bitrates (Recommended)

Install the dependency:

python -m pip install pyserial

The complete code below automatically finds both management ports of one connected SPINE V8 on Windows or Linux. It sends the same setting to both MCUs, thereby configuring CAN-1 through CAN-4 without requiring any management-port or board-interface mapping. This example configures classic CAN to 1 Mbps. The 5 Mbps CAN FD data-phase value is the required second command argument and does not affect classic CAN communication.

import re
import time
import serial
from serial.tools import list_ports

COMMANDS = ["AT+SETFDCAN=1000000,5000000"]

def is_management_port(port):
    if (port.vid, port.pid) != (0x1209, 0x2323):
        return False
    info = " ".join(str(getattr(port, name, "") or "")
                    for name in ("hwid", "interface", "location")).upper()
    return ("MI_01" in info or "MANAGEMENT PORT" in info or
            re.search(r":(?:X|\d+)\.1(?:\D|$)", info) is not None)

def send_at(stream, command):
    stream.reset_input_buffer()
    stream.write(command.encode("ascii") + b"\r\n")
    stream.flush()
    deadline, reply = time.monotonic() + 1.0, bytearray()
    while time.monotonic() < deadline:
        reply.extend(stream.read(stream.in_waiting or 1))
        if b"OK\r\n" in reply or b"ERR," in reply:
            break
    text = reply.decode("ascii", errors="replace").strip()
    if "OK" not in text:
        raise RuntimeError(f"{stream.port}: {command}: {text or 'no reply'}")
    print(f"{stream.port}: {command} -> {text}")

ports = sorted(p.device for p in list_ports.comports()
               if is_management_port(p))
if len(ports) != 2:
    raise SystemExit(f"Expected 2 SANPO management ports, found {len(ports)}: {ports}")

for device in ports:
    with serial.Serial(device, 1_000_000, timeout=0.05, write_timeout=1) as stream:
        time.sleep(0.05)
        for command in COMMANDS:
            send_at(stream, command)

print("CAN-1..CAN-4 configured successfully.")

To use another classic CAN bitrate, change only the first number in COMMANDS. The 1_000_000 used to open the management port is only a CDC API parameter; it does not set the physical CAN or RS485 bitrate. Only the explicit AT+SETFDCAN command changes the physical bus settings.

Parameter	Supported values
CAN bitrate	1000000, 500000, 250000, 125000, 100000

CAN Extended Frame

Send and receive use the same format:

Field	Length	Description
Header	2 bytes	Fixed 45 54, or ET
Channel	1 byte	CAN interface number
CAN ID	4 bytes	29-bit extended ID, big-endian
Data length	1 byte	0 to 8
CAN data	0-8 bytes	Must match the preceding length
Trailer	2 bytes	Fixed 0D 0A

Send 8 data bytes to Channel 1 with extended ID 0x0000FD01:

45 54 01 00 00 FD 01 08 01 02 03 04 05 06 07 08 0D 0A

CAN Standard Frame

Send and receive use the same format:

Field	Length	Description
Header	2 bytes	Fixed 53 54, or ST
Channel	1 byte	CAN interface number
Reserved	2 bytes	Fixed 00 00
CAN ID	2 bytes	11-bit standard ID, big-endian
Data length	1 byte	0 to 8
CAN data	0-8 bytes	Must match the preceding length
Trailer	2 bytes	Fixed 0D 0A

Send 4 data bytes to Channel 2 with standard ID 0x142:

53 54 02 00 00 01 42 04 11 22 33 44 0D 0A

Xiaomi CyberGear Example

Example program: USB to CAN CyberGear example

Windows example:

python usb2can_cybergear_demo_v8.py --port COM8 --motors 1 --channel 1

Linux example:

sudo python3 usb2can_cybergear_demo_v8.py --port /dev/ttyACM0 --motors 1 --channel 1

Adjust the serial port, interface, and motor ID for the actual installation.

Troubleshooting

Symptom	Action
USB serial port cannot be found	Check the USB cable, power for the control section, and reconnect the board
No reply after sending	Check the USB port mapping, Channel, CAN ID, bit rate, termination resistors, wiring, and device power
The frame is sent to both CAN interfaces	Channel is 0x00; select a specific channel
Reply Channel differs from board CAN-3/4	Replies use local 1/2 numbering on the current MCU; this is normal
Reply format differs from this page	Send AT+ET as text, wait for OK, and retry