AT32 SPI

AT32 SPI — CRC 校验轮询传输

AT32 AT32F403A_407_Firmware_Library V2.2.2 SPI CRC 校验轮询传输 示例教学

SPI — CRC 校验轮询传输

固件库: AT32F403A_407_Firmware_Library V2.2.2
芯片: AT32
源文件: AT32/AT32F403A_407_Firmware_Library_V2.2.2/project/at_start_f403a/examples/spi/crc_transfer_polling/src/main.c

功能简介

本示例演示 SPI 通信中使用 CRC 校验。发送方自动附加 CRC，接收方自动校验，确保数据完整性。

硬件准备

  • 需要主机和从机两块板子，或使用回环连接（MOSI→MISO）

完整代码 

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#include "at32f403a_407_board.h"
#include "at32f403a_407_clock.h"
#include <stdio.h>
#define SPI_MASTER_CS_HIGH   gpio_bits_set(GPIOA, GPIO_PINS_4)
#define SPI_MASTER_CS_LOW    gpio_bits_reset(GPIOA, GPIO_PINS_4)
#define BUFFER_SIZE          32

static void spi_config(void)
{
  spi_init_type spi_init_struct;
  
  /* master spi initialization */
  crm_periph_clock_enable(CRM_SPI1_PERIPH_CLOCK, TRUE);
  spi_default_para_init(&spi_init_struct);
  
  /* dual line unidirectional full-duplex mode */
  spi_init_struct.transmission_mode = SPI_TRANSMIT_FULL_DUPLEX;
  spi_init_struct.master_slave_mode = SPI_MODE_MASTER;
  spi_init_struct.mclk_freq_division = SPI_MCLK_DIV_8;
  spi_init_struct.first_bit_transmission = SPI_FIRST_BIT_MSB;
  spi_init_struct.frame_bit_num = SPI_FRAME_16BIT;
  spi_init_struct.clock_polarity = SPI_CLOCK_POLARITY_LOW;
  spi_init_struct.clock_phase = SPI_CLOCK_PHASE_2EDGE;
  spi_init_struct.cs_mode_selection = SPI_CS_SOFTWARE_MODE;
  spi_init(SPI1, &spi_init_struct);
  
  /* hardware crc calculation config */
  spi_crc_polynomial_set(SPI1, 7);
  spi_crc_enable(SPI1, TRUE);
  
  spi_enable(SPI1, TRUE);
  
  /* slave spi initialization */
  crm_periph_clock_enable(CRM_SPI2_PERIPH_CLOCK, TRUE);
  
  /* dual line unidirectional full-duplex mode */
  spi_init_struct.transmission_mode = SPI_TRANSMIT_FULL_DUPLEX;
  spi_init_struct.master_slave_mode = SPI_MODE_SLAVE;
  spi_init_struct.mclk_freq_division = SPI_MCLK_DIV_8;
  spi_init_struct.first_bit_transmission = SPI_FIRST_BIT_MSB;
  spi_init_struct.frame_bit_num = SPI_FRAME_16BIT;
  spi_init_struct.clock_polarity = SPI_CLOCK_POLARITY_LOW;
  spi_init_struct.clock_phase = SPI_CLOCK_PHASE_2EDGE;
  spi_init_struct.cs_mode_selection = SPI_CS_HARDWARE_MODE;
  spi_init(SPI2, &spi_init_struct);
  
  /* hardware crc calculation config */
  spi_crc_polynomial_set(SPI2, 7);
  spi_crc_enable(SPI2, TRUE);
  
  spi_enable(SPI2, TRUE);
}

static void gpio_config(void)
{
  gpio_init_type gpio_initstructure;
  crm_periph_clock_enable(CRM_GPIOA_PERIPH_CLOCK, TRUE);
  crm_periph_clock_enable(CRM_GPIOB_PERIPH_CLOCK, TRUE);
  
  /* master spi cs pin */
  gpio_initstructure.gpio_out_type = GPIO_OUTPUT_PUSH_PULL;
  gpio_initstructure.gpio_pull = GPIO_PULL_UP;
  gpio_initstructure.gpio_mode = GPIO_MODE_OUTPUT;
  gpio_initstructure.gpio_drive_strength = GPIO_DRIVE_STRENGTH_STRONGER;
  gpio_initstructure.gpio_pins = GPIO_PINS_4;
  gpio_init(GPIOA, &gpio_initstructure);
  
  /* non communication time: master pull up CS pin release slave */
  SPI_MASTER_CS_HIGH;
  
  /* master spi sck pin */
  gpio_initstructure.gpio_out_type = GPIO_OUTPUT_PUSH_PULL;
  gpio_initstructure.gpio_pull = GPIO_PULL_DOWN;
  gpio_initstructure.gpio_mode = GPIO_MODE_MUX;
  gpio_initstructure.gpio_drive_strength = GPIO_DRIVE_STRENGTH_STRONGER;
  gpio_initstructure.gpio_pins = GPIO_PINS_5;
  gpio_init(GPIOA, &gpio_initstructure);
  
  /* master spi miso pin */
  gpio_initstructure.gpio_out_type = GPIO_OUTPUT_PUSH_PULL;
  gpio_initstructure.gpio_pull = GPIO_PULL_UP;
  gpio_initstructure.gpio_mode = GPIO_MODE_INPUT;
  gpio_initstructure.gpio_drive_strength = GPIO_DRIVE_STRENGTH_STRONGER;
  gpio_initstructure.gpio_pins = GPIO_PINS_6;
  gpio_init(GPIOA, &gpio_initstructure);
  
  /* master spi mosi pin */
  gpio_initstructure.gpio_out_type = GPIO_OUTPUT_PUSH_PULL;
  gpio_initstructure.gpio_pull = GPIO_PULL_UP;
  gpio_initstructure.gpio_mode = GPIO_MODE_MUX;
  gpio_initstructure.gpio_drive_strength = GPIO_DRIVE_STRENGTH_STRONGER;
  gpio_initstructure.gpio_pins = GPIO_PINS_7;
  gpio_init(GPIOA, &gpio_initstructure);
  
  /* slave spi cs pin */
  gpio_initstructure.gpio_out_type = GPIO_OUTPUT_PUSH_PULL;
  gpio_initstructure.gpio_pull = GPIO_PULL_UP;
  gpio_initstructure.gpio_mode = GPIO_MODE_INPUT;
  gpio_initstructure.gpio_drive_strength = GPIO_DRIVE_STRENGTH_STRONGER;
  gpio_initstructure.gpio_pins = GPIO_PINS_12;
  gpio_init(GPIOB, &gpio_initstructure);
  
  /* slave spi sck pin */
  gpio_initstructure.gpio_out_type = GPIO_OUTPUT_PUSH_PULL;
  gpio_initstructure.gpio_pull = GPIO_PULL_DOWN;
  gpio_initstructure.gpio_mode = GPIO_MODE_INPUT;
  gpio_initstructure.gpio_drive_strength = GPIO_DRIVE_STRENGTH_STRONGER;
  gpio_initstructure.gpio_pins = GPIO_PINS_13;
  gpio_init(GPIOB, &gpio_initstructure);
  
  /* slave spi miso pin */
  gpio_initstructure.gpio_out_type = GPIO_OUTPUT_PUSH_PULL;
  gpio_initstructure.gpio_pull = GPIO_PULL_UP;
  gpio_initstructure.gpio_mode = GPIO_MODE_MUX;
  gpio_initstructure.gpio_drive_strength = GPIO_DRIVE_STRENGTH_STRONGER;
  gpio_initstructure.gpio_pins = GPIO_PINS_14;
  gpio_init(GPIOB, &gpio_initstructure);
  
  /* slave spi mosi pin */
  gpio_initstructure.gpio_out_type = GPIO_OUTPUT_PUSH_PULL;
  gpio_initstructure.gpio_pull = GPIO_PULL_UP;
  gpio_initstructure.gpio_mode = GPIO_MODE_INPUT;
  gpio_initstructure.gpio_drive_strength = GPIO_DRIVE_STRENGTH_STRONGER;
  gpio_initstructure.gpio_pins = GPIO_PINS_15;
  gpio_init(GPIOB, &gpio_initstructure);
}

int main(void)
{
  system_clock_config();
  at32_board_init();
  at32_led_on(LED4);
  gpio_config();
  spi_config();
  
  /* start communication: master pull down CS pin select slave */
  SPI_MASTER_CS_LOW;
  
  /* transfer procedure:the "BUFFER_SIZE-1" data transfer */
  while(tx_index < BUFFER_SIZE - 1)
  {
    /* slave and master transmit data fill */
    while(spi_i2s_flag_get(SPI2, SPI_I2S_TDBE_FLAG) == RESET);
    spi_i2s_data_transmit(SPI2, spi2_tx_buffer[tx_index]);
    while(spi_i2s_flag_get(SPI1, SPI_I2S_TDBE_FLAG) == RESET);
    spi_i2s_data_transmit(SPI1, spi1_tx_buffer[tx_index++]);
    
    /* slave and master receive data get */
    while(spi_i2s_flag_get(SPI2, SPI_I2S_RDBF_FLAG) == RESET);
    spi2_rx_buffer[rx_index] = spi_i2s_data_receive(SPI2);
    while(spi_i2s_flag_get(SPI1, SPI_I2S_RDBF_FLAG) == RESET);
    spi1_rx_buffer[rx_index++] = spi_i2s_data_receive(SPI1);
  }
  
  /* wait master and slave transmit data buffer empty */
  while(spi_i2s_flag_get(SPI1, SPI_I2S_TDBE_FLAG) == RESET);
  while(spi_i2s_flag_get(SPI2, SPI_I2S_TDBE_FLAG) == RESET);

  /* transfer procedure:the last data and crc transfer */
  /* slave the last transmit data fill and crc transfer setting */
  spi_i2s_data_transmit(SPI2, spi2_tx_buffer[tx_index]);
  spi_crc_next_transmit(SPI2);
  
  /* master the last transmit data fill and crc transfer setting */
  spi_i2s_data_transmit(SPI1, spi1_tx_buffer[tx_index]);
  spi_crc_next_transmit(SPI1);
  
  /* wait master and slave the last data transfer end */
  while(spi_i2s_flag_get(SPI1, SPI_I2S_RDBF_FLAG) == RESET);
  spi1_rx_buffer[rx_index] = spi_i2s_data_receive(SPI1);
  while(spi_i2s_flag_get(SPI2, SPI_I2S_RDBF_FLAG) == RESET);
  spi2_rx_buffer[rx_index] = spi_i2s_data_receive(SPI2);
  
  /* wait master and slave the crc transfer end */
  while(spi_i2s_flag_get(SPI1, SPI_I2S_RDBF_FLAG) == RESET);
  while(spi_i2s_flag_get(SPI2, SPI_I2S_RDBF_FLAG) == RESET);
  
  /* wait master and slave idle when communication end */
  while(spi_i2s_flag_get(SPI1, SPI_I2S_BF_FLAG) != RESET);
  while(spi_i2s_flag_get(SPI2, SPI_I2S_BF_FLAG) != RESET);
  
  /* end communication: master pull up CS pin release slave */
  SPI_MASTER_CS_HIGH;

  /* test result:the data and crc check */
  transfer_status1 = buffer_compare(spi2_rx_buffer, spi1_tx_buffer, BUFFER_SIZE);
  transfer_status2 = buffer_compare(spi1_rx_buffer, spi2_tx_buffer, BUFFER_SIZE);
  if((spi_i2s_flag_get(SPI1, SPI_CCERR_FLAG)) != RESET)
  {
    spi_i2s_flag_clear(SPI1, SPI_CCERR_FLAG);
    transfer_status2 = ERROR;
  }
  if((spi_i2s_flag_get(SPI2, SPI_CCERR_FLAG)) != RESET)
  {
    spi_i2s_flag_clear(SPI2, SPI_CCERR_FLAG);
    transfer_status1 = ERROR;
  }
  crc1_value = spi_i2s_data_receive(SPI1);
  crc2_value = spi_i2s_data_receive(SPI2);

  /* test result indicate:if SUCCESS ,led2 lights */
  if((transfer_status1 == SUCCESS) && (transfer_status2 == SUCCESS))
  {
    at32_led_on(LED2);
  }
  else
  {
    at32_led_on(LED3);
  }
  while(1)
  {
  }
}

代码讲解

系统时钟初始化：配置 MCU 的主频和时钟树。不同芯片的时钟配置不同，一般由工具生成。

板级初始化：初始化开发板上的 LED、按键等基础外设。

GPIO 配置：设置引脚为输出/输入模式，选择推挽/开漏输出，配置上拉/下拉。

SPI 配置：设置主/从模式、时钟极性（CPOL）、时钟相位（CPHA）、分频系数。主机和从机的 CPOL/CPHA 必须一致。

实验现象

  • 主机和从机互相交换数据
  • 数据校验通过则 LED 指示成功

注意事项

  • CPOL 和 CPHA 必须主机从机一致
  • 片选（CS）信号要手动拉低选中从机
  • 时钟频率不能超过从设备的最大速率
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