26.3.2. lin_slave

26.3.2.1. Overview

This example demonstrates the basic functionality of HPM LIN peripheral in slave mode, including:

  • Support for LIN 2.2A protocol specification

  • Data transmission and reception in slave mode

  • Enhanced checksum mode support

  • Sleep and wakeup functionality

  • Bus idle timeout detection

  • Maximum 8-byte data transfer support

26.3.2.2. Operation Flow

  1. Initialization Configuration

    • Initialize LIN pin configuration

    • Configure LIN clock to 20MHz

    • Configure interrupt priority

    • Initialize transmit data buffer

  2. Main Loop Processing

    • Wait for master request

    • Execute operations based on received frame ID:

      • ID 0x31: Receive 8 bytes of data

      • ID 0x30: Transmit 8 bytes of data

    • Handle various events:

      • Transfer completion event

      • Wakeup event

      • Error event

      • Bus idle timeout event

  3. Interrupt Handling

    • Process master data request

    • Handle transfer errors

    • Process bus idle timeout

    • Handle wakeup signal

    • Process transfer completion

26.3.2.3. Board Setting

This example requires the following hardware:

  • A LIN transceiver

  • A USB_LIN debugger (as master)

  • Connection cables

Please refer to Pin Description for specific board. Connect LIN transceiver MCU signal to LIN’s TX and RX on board, connect LIN transceiver LIN signal to USB_LIN debugger.

26.3.2.4. Running the Example

To run this program, USB_LIN debugger configuration is required:

  1. Configure Basic Parameters

    • Select correct COM port and baud rate

    • Click “Set to Debugger” button

    lin_debugger_configuration

  2. Configure Master Communication Parameters

    • Configure transmission window parameters

    • Set master transmission and reception configuration

    • Set synchronization interval (for waking up slave from sleep mode)

    • Click “Configure to Debugger” button

    lin_debugger_master_sent

When the example runs successfully, the log would be seen on the terminal like:

LIN slave example
LIN bus timeout, will enter sleep mode
LIN wakeup
ID: 31, receive 8 bytes
0 1 2 3 4 5 6 7
ID: 30, sent 8 bytes
7 6 5 4 3 2 1 0

The debugger window will show the following result:

lin_debugger_master_result

26.3.2.5. Debugging Tips

  1. Hardware Connection Check

    • Ensure proper connection between LIN transceiver and development board

    • Check power and ground connections

  2. Baud Rate Configuration

    • Ensure baud rate matches between master and slave devices

    • Default baud rate is 19200bps

  3. Frame Format Issues

    • ID mismatch: Verify configured ID matches master’s transmitted ID

    • Verify checksum mode configuration matches

  4. Common Error Analysis

    • Check if interrupts are triggered normally, examine status register to locate specific errors

    • Use oscilloscope to observe LIN bus signal waveform