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ISOTPlib

ISOTPlib is a flexible C library designed to make implementing the ISO-TP CAN communication layer a breeze. It can be used for raw data transfer, but it is designed to be used as an abstraction layer between a CAN interface and the UDS FlexDiag library. Unlike other libraries, this one is not designed to deal with loops, arbitration IDs, timers, or CAN drivers - instead only taking care of what ISO-TP is actually responsible for.

🚀 Key Features

  • Simple operation: Simply register callbacks at setup, pass in recieved CAN frames, and check for frames to send and you're good to send and recieve transmissions!
  • No dynamic memory allocation required: The library is designed to be used with statically allocated buffers, but dynamic buffer sizes can be used if desired.
  • Non-intrusive scope: ISOTPlib does not handle CAN IDs, CAN interfaces, or data processing. It also has no loop. It simply handles incoming frames and generates outgoing frames by request to facilitate single/multi-frame transfers.
  • Concurrent Sessions: The struct-based design allows for an unlimited number of sessions.
  • Error Detection: Missed continuous frame and timeout callbacks
  • Customizable Padding: Each instance can have outgoing frames padded with a custom byte or sent at actual length depending on recievers requirements.

🎯 Goals

  • Reliability: Statically allocated memory and clear code design patterns
  • FlexDiag: Easily tie into the powerful UDS-based framework of FlexDiag
  • Platform-agnostic: Codebase compatible with embedded/Arduino/Desktop and independent of CAN interfaces or libraries

📖 Use Cases

  • Automotive Diagnostics

✏️ How to implement

  1. Create a isotp_session_t and initialize it with isotp_session_init(...)
  2. Register desired callbacks
  3. When a CAN message is recieved, call isotp_session_can_rx(isotp_session_t* session, const uint8_t* frame_data, const size_t frame_length)
  4. To send a CAN message, call size_t isotp_session_can_tx(isotp_session_t* session, uint8_t* frame_data, const size_t frame_size, uint32_t* requested_separation_uS)
    • To support separation time, don't check again for the provided requested_separation_uS has elapsed
  5. Done!
    • Don't forget to call isotp_session_idle(isotp_session_t* session) in your recieved data callback to release the session, even if you didn't respond.
    • If you'd like, you can change protocol options (padding byte, padding enabled, etc) in the session's isotp_protocol_config_t