UTILS FDCAN How to Use

group UTILS_FDCAN_How_To_Use

How to use the UTILS FDCAN Timing module

This module provides utility functions for FDCAN timing calculations covering two main use cases:

A. Computation of Bit Timings from Bus Parameters

Compute the FDCAN bit timing parameters (prescaler, time segments, etc.) from desired bus parameters such as bitrate, sample point, and clock frequency.

Steps:

1. Fill a stm32_utils_fdcan_input_bus_param_t structure with the desired bus parameters:

   • FDCAN kernel clock (kHz)

   • Desired bitrate (kbit/s)

   • Desired sample point (per mille)

   • Maximum allowed bitrate tolerance (per mille)

2. Call STM32_UTILS_FDCAN_ComputeBitTiming() with:

   • Pointer to input bus parameters

   • Bit timing type (nominal or data)

   • Pointer to a stm32_utils_fdcan_bit_timing_t structure to receive the computed timings

   • Pointer to a stm32_utils_fdcan_output_config_t structure to receive the real bus parameters

3. Apply the computed timings to the FDCAN peripheral configuration:

   • Fill a hal_fdcan_nominal_bit_timing_t or hal_fdcan_data_bit_timing_t structure with the computed values.

   • Call HAL_FDCAN_SetConfig() or dedicated functions HAL_FDCAN_SetNominalBitTiming() and HAL_FDCAN_SetDataBitTiming() to apply the timing settings.

B. Computation of Bus Parameters from Bit Timings

Compute the resulting bus parameters (bitrate, sample point) from known bit timing parameters (prescaler, time segments, etc.).

Steps:

1. Fill a stm32_utils_fdcan_bit_timing_t structure with the bit timing values:

   • Prescaler

   • Time segment 1

   • Time segment 2

   • Synchronization jump width

   • Remark: Use the functions HAL_FDCAN_GetNominalBitTiming() or HAL_FDCAN_GetDataBitTiming() to retrieve the current bit timing settings.

2. Call STM32_UTILS_FDCAN_ComputeBitrate() with:

   • Pointer to the bit timing structure

   • FDCAN kernel clock (kHz)

   • Pointer to a stm32_utils_fdcan_output_config_t structure to receive the computed bus parameters

3. Use the computed bus parameters as needed in the application.