AT32 I2S — 半双工中断

AT32 AT32F403A_407_Firmware_Library V2.2.2 I2S 半双工中断 示例教学

I2S — 半双工中断

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/i2s/halfduplex_interrupt/src/main.c


功能简介

本示例演示 I2S 音频总线通信。I2S 是数字音频传输标准,常用于连接 DAC/ADC 音频芯片、MEMS 麦克风等。

完整代码

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#include "at32f403a_407_board.h"
#include "at32f403a_407_clock.h"
#include <stdio.h>

static void i2s_config(i2s_data_channel_format_type format, i2s_audio_sampling_freq_type freq)
{
  i2s_init_type i2s_init_struct;
  
  /* master i2s initialization */
  crm_periph_clock_enable(CRM_SPI3_PERIPH_CLOCK, TRUE);
  nvic_irq_enable(SPI3_I2S3EXT_IRQn, 0, 0);
  spi_i2s_reset(SPI3);
  i2s_default_para_init(&i2s_init_struct);
  
  /* master transmission mode */
  i2s_init_struct.audio_protocol = I2S_AUDIO_PROTOCOL_PHILLIPS;
  i2s_init_struct.data_channel_format = format;
  i2s_init_struct.mclk_output_enable = TRUE;
  i2s_init_struct.audio_sampling_freq = freq;
  i2s_init_struct.clock_polarity = I2S_CLOCK_POLARITY_LOW;
  i2s_init_struct.operation_mode = I2S_MODE_MASTER_TX;
  i2s_init(SPI3, &i2s_init_struct);
  
  /* enable transmit data buffer empty interrupt */
  spi_i2s_interrupt_enable(SPI3, SPI_I2S_TDBE_INT, TRUE);
  
  /* slave i2s initialization */
  crm_periph_clock_enable(CRM_SPI2_PERIPH_CLOCK, TRUE);
  nvic_irq_enable(SPI2_I2S2EXT_IRQn, 0, 0);
  spi_i2s_reset(SPI2);
  
  /* slave reception mode */
  i2s_init_struct.audio_protocol = I2S_AUDIO_PROTOCOL_PHILLIPS;
  i2s_init_struct.data_channel_format = format;
  i2s_init_struct.mclk_output_enable = TRUE;
  i2s_init_struct.audio_sampling_freq = freq;
  i2s_init_struct.clock_polarity = I2S_CLOCK_POLARITY_LOW;
  i2s_init_struct.operation_mode =I2S_MODE_SLAVE_RX;
  i2s_init(SPI2, &i2s_init_struct);
  
  /* enable receive data buffer full interrupt */
  spi_i2s_interrupt_enable(SPI2, SPI_I2S_RDBF_INT, 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);
  crm_periph_clock_enable(CRM_GPIOC_PERIPH_CLOCK, TRUE);
  crm_periph_clock_enable(CRM_IOMUX_PERIPH_CLOCK, TRUE);
  gpio_pin_remap_config(SWJTAG_GMUX_010, TRUE);

  /* master i2s ws 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_15;
  gpio_init(GPIOA, &gpio_initstructure);

  /* master i2s ck pin */
  gpio_initstructure.gpio_pull = GPIO_PULL_DOWN;
  gpio_initstructure.gpio_mode = GPIO_MODE_MUX;
  gpio_initstructure.gpio_pins = GPIO_PINS_3;
  gpio_init(GPIOB, &gpio_initstructure);

  /* master i2s sd pin */
  gpio_initstructure.gpio_pull = GPIO_PULL_UP;
  gpio_initstructure.gpio_mode = GPIO_MODE_MUX;
  gpio_initstructure.gpio_pins = GPIO_PINS_5;
  gpio_init(GPIOB, &gpio_initstructure);

  /* master i2s mck pin */
  gpio_initstructure.gpio_pull = GPIO_PULL_UP;
  gpio_initstructure.gpio_mode = GPIO_MODE_MUX;
  gpio_initstructure.gpio_pins = GPIO_PINS_7;
  gpio_init(GPIOC, &gpio_initstructure);

  /* slave i2s ws 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 i2s ck pin */
  gpio_initstructure.gpio_pull = GPIO_PULL_DOWN;
  gpio_initstructure.gpio_mode = GPIO_MODE_INPUT;
  gpio_initstructure.gpio_pins = GPIO_PINS_13;
  gpio_init(GPIOB, &gpio_initstructure);

  /* slave i2s sd pin */
  gpio_initstructure.gpio_pull = GPIO_PULL_UP;
  gpio_initstructure.gpio_mode = GPIO_MODE_INPUT;
  gpio_initstructure.gpio_pins = GPIO_PINS_15;
  gpio_init(GPIOB, &gpio_initstructure);
}

int main(void)
{
  __IO uint32_t index = 0;
  nvic_priority_group_config(NVIC_PRIORITY_GROUP_4);
  system_clock_config();
  at32_board_init();
  at32_led_on(LED4);
  gpio_config();
  i2s_config(I2S_DATA_16BIT_CHANNEL_32BIT, I2S_AUDIO_FREQUENCY_48K);
  
  /* enable slave and master i2s to start communication */
  i2s_enable(SPI2, TRUE);
  i2s_enable(SPI3, TRUE);
  
  /* wait data receive end */
  while(rx_index < 32);
  
  /* wait master and slave idle when communication end */
  while(spi_i2s_flag_get(SPI3, SPI_I2S_BF_FLAG) != RESET);
  while(spi_i2s_flag_get(SPI2, SPI_I2S_BF_FLAG) != RESET);

  /* test result:the data check */
  transfer_status1 = buffer_compare(i2s2_buffer_rx, i2s3_buffer_tx, 32);

  /* receive buffer clear */
  tx_index = 0;
  rx_index = 0;
  for(index = 0; index < 32; index++)
  {
    i2s2_buffer_rx[index] = 0;
  }
  
  /* change frame format */
  i2s_config(I2S_DATA_24BIT_CHANNEL_32BIT, I2S_AUDIO_FREQUENCY_16K);
  
  /* enable slave and master i2s to start communication */
  i2s_enable(SPI2, TRUE);
  i2s_enable(SPI3, TRUE);
  
  /* wait data receive end */
  while(rx_index < 32);
  
  /* wait master and slave idle when communication end */
  while(spi_i2s_flag_get(SPI3, SPI_I2S_BF_FLAG) != RESET);
  while(spi_i2s_flag_get(SPI2, SPI_I2S_BF_FLAG) != RESET);

  /* test result:the data check */
  transfer_status2 = buffer_compare_24bits(i2s2_buffer_rx, i2s3_buffer_tx, 32);

  /* test result indicate:if passed ,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。

中断优先级配置:NVIC 设置中断的抢占优先级和子优先级。数字越小优先级越高。

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