AT32 I2S

AT32 I2S — 半双工 DMA

AT32 AT32F403A_407_Firmware_Library V2.2.2 I2S 半双工 DMA 示例教学

I2S — 半双工 DMA

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_dma/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 dma_config(void)
{
  dma_init_type dma_init_struct;

  crm_periph_clock_enable(CRM_DMA1_PERIPH_CLOCK, TRUE);
  crm_periph_clock_enable(CRM_DMA2_PERIPH_CLOCK, TRUE);
  
  /* use dma2_channel2 as spi3 transmit channel */
  dma_reset(DMA2_CHANNEL2);
  dma_default_para_init(&dma_init_struct);
  dma_init_struct.buffer_size = 32;
  dma_init_struct.direction = DMA_DIR_MEMORY_TO_PERIPHERAL;
  dma_init_struct.memory_base_addr = (uint32_t)i2s3_buffer_tx;
  dma_init_struct.memory_data_width = DMA_MEMORY_DATA_WIDTH_HALFWORD;
  dma_init_struct.memory_inc_enable = TRUE;
  dma_init_struct.peripheral_base_addr = (uint32_t)&(SPI3->dt);
  dma_init_struct.peripheral_data_width = DMA_PERIPHERAL_DATA_WIDTH_HALFWORD;
  dma_init_struct.peripheral_inc_enable = FALSE;
  dma_init_struct.priority = DMA_PRIORITY_HIGH;
  dma_init_struct.loop_mode_enable = FALSE;
  dma_init(DMA2_CHANNEL2, &dma_init_struct);
  
  /* use dma1_channel4 as spi2 receive channel */
  dma_reset(DMA1_CHANNEL4);
  dma_init_struct.buffer_size = 32;
  dma_init_struct.direction = DMA_DIR_PERIPHERAL_TO_MEMORY;
  dma_init_struct.memory_base_addr = (uint32_t)i2s2_buffer_rx;
  dma_init_struct.memory_data_width = DMA_MEMORY_DATA_WIDTH_HALFWORD;
  dma_init_struct.memory_inc_enable = TRUE;
  dma_init_struct.peripheral_base_addr = (uint32_t)&(SPI2->dt);
  dma_init_struct.peripheral_data_width = DMA_PERIPHERAL_DATA_WIDTH_HALFWORD;
  dma_init_struct.peripheral_inc_enable = FALSE;
  dma_init_struct.priority = DMA_PRIORITY_HIGH;
  dma_init_struct.loop_mode_enable = FALSE;
  dma_init(DMA1_CHANNEL4, &dma_init_struct);
}

static void i2s_config(void)
{
  i2s_init_type i2s_init_struct;
  
  /* master i2s initialization */
  crm_periph_clock_enable(CRM_SPI3_PERIPH_CLOCK, TRUE);
  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 = I2S_DATA_16BIT_CHANNEL_32BIT;
  i2s_init_struct.mclk_output_enable = TRUE;
  i2s_init_struct.audio_sampling_freq = I2S_AUDIO_FREQUENCY_48K;
  i2s_init_struct.clock_polarity = I2S_CLOCK_POLARITY_LOW;
  i2s_init_struct.operation_mode = I2S_MODE_MASTER_TX;
  i2s_init(SPI3, &i2s_init_struct);
  
  /* use dma transmit */
  spi_i2s_dma_transmitter_enable(SPI3, TRUE);
  
  i2s_enable(SPI3, TRUE);
  
  /* slave i2s initialization */
  crm_periph_clock_enable(CRM_SPI2_PERIPH_CLOCK, TRUE);
  
  /* slave reception mode */
  i2s_init_struct.audio_protocol = I2S_AUDIO_PROTOCOL_PHILLIPS;
  i2s_init_struct.data_channel_format = I2S_DATA_16BIT_CHANNEL_32BIT;
  i2s_init_struct.mclk_output_enable = TRUE;
  i2s_init_struct.audio_sampling_freq = I2S_AUDIO_FREQUENCY_48K;
  i2s_init_struct.clock_polarity = I2S_CLOCK_POLARITY_LOW;
  i2s_init_struct.operation_mode = I2S_MODE_SLAVE_RX;
  i2s_init(SPI2, &i2s_init_struct);

  /* use dma receive */
  spi_i2s_dma_receiver_enable(SPI2, TRUE);
  
  i2s_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);
  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)
{
  system_clock_config();
  at32_board_init();
  at32_led_on(LED4);
  gpio_config();
  dma_config();
  i2s_config();
  
  /* enable i2s slave dma to get data */
  dma_channel_enable(DMA1_CHANNEL4, TRUE);
  
  /* enable i2s master dma to fill data */
  dma_channel_enable(DMA2_CHANNEL2, TRUE);

  /* wait slave i2s data receive end */
  while(dma_flag_get(DMA1_FDT4_FLAG) == RESET)
  {
  }
  
  /* 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_status = buffer_compare(i2s2_buffer_rx, i2s3_buffer_tx, 32);

  /* test result indicate:if passed ,led2 lights */
  if(transfer_status==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。

DMA 配置：设置源地址、目标地址、传输方向、数据宽度。DMA 搬运数据不占用 CPU。

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。

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