Project Description

The main purpose of this expansion board is to develop and use OBD and UDS protocols related to automotive diagnosis.

Can support common automotive diagnostic protocols:

• ISO 9141-2 (5 baud initialization, 10.4K baud)
• ISO 14230-4 KWP (5 baud initialization, 10.4K baud)
• ISO 14230-4 KWP (fast initialization, 10.4K baud rate)
• ISO 15765-4 CAN (11bit ID, 500K baud rate)
• ISO 15765-4 CAN (29bit ID, 500K baud rate)
• ISO 15765-4 CAN (11bit ID, 250K baud rate)
• ISO 15765-4 CAN (29bit ID, 250K baud rate)
• SAE J1939 CAN (250K baud rate)
• SAE J1939 CAN (500K baud rate)

Some older protocols in OBD, such as SAE J1850, have been phased out and are no longer supported.

Onboard 2 channels CAN/CAN-FD, 1 channel LIN/K line, 1 channel RS232, 1 channel RS485 and 1 channel Ethernet interface.

The diagnostic data obtained from the CAN/LIN/K line can be forwarded through the above interface to realize the function of the vehicle diagnostic instrument.

These onboard interfaces are common industrial control interfaces and can be used for data transmission between interfaces to achieve industrial control data forwarding/transparent transmission functions.

Function

Software programming can achieve:

• CAN to RS485, to RS232
• LIN/K line to RS485, to RS232
• CAN and LIN/K line conversion
• 2-way CAN mutual conversion
• The combination of 1 CAN and 1 K line can implement the OBDII diagnostic protocol (omitting obsolete communication protocols such as J1850)

Onboard 12V boost circuit, the reference level of LIN/K line can be selected from external interface 12V or internal 12V, theoretically compatible with 24V system, not tested.

The expansion board hardware only has LIN master configuration and does not support slave machines. Vehicle diagnostic use only requires host configuration.

After adding the corresponding host computer functions, the functions of CAN / LIN / K line diagnostic instrument can be realized.

Through the native USB, UART to USB, WiFi, and Bluetooth interfaces on the baseboard, data can also be forwarded through the aforementioned four interfaces.

The UART interface is introduced before the RS485/RS232 conversion chip, and the I2C interface is also introduced (without a pull-up resistor). These interfaces can be connected to external sensor modules, and the WiFi and Bluetooth on the baseboard can also implement some IoT functions.

This solution only performs simple CAN bus ESD and anti-interference processing, but does not perform complete isolation and anti-static processing. It is recommended for diagnostic function prototype verification and is not suitable for use in environments with strong interference or possible exposure to high-voltage static electricity.

Main chip

• CAN transceiver: TJA1042
• LIN/K line transceiver: TJA1027
• UART to RS232: SP3232
• UART to RS485: SP3485
• Ethernet PHY: LAN8720
• 12V boost: MAX662

Main resources and pins