AT32 TMR — DMA 突发传输

Tue, 08 Sep 2026 14:52:21 +0800

TMR — DMA 突发传输

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/tmr/dma_burst/src/main.c

功能简介

本示例演示定时器 DMA 触发。定时器事件自动触发 DMA 传输，无需 CPU 干预，适合波形生成等高速场景。

完整代码

#include "at32f403a_407_board.h"
#include "at32f403a_407_clock.h"

int main(void)
{
  system_clock_config();

  at32_board_init();

  /* get system clock */
  crm_clocks_freq_get(&crm_clocks_freq_struct);

  /* turn led2/led3/led4 on */
  at32_led_on(LED2);
  at32_led_on(LED3);
  at32_led_on(LED4);

  /* enable tmr1/gpioa/gpiob/dma clock */
  crm_periph_clock_enable(CRM_TMR1_PERIPH_CLOCK, TRUE);
  crm_periph_clock_enable(CRM_DMA1_PERIPH_CLOCK, TRUE);
  crm_periph_clock_enable(CRM_GPIOA_PERIPH_CLOCK, TRUE);
  crm_periph_clock_enable(CRM_GPIOB_PERIPH_CLOCK, TRUE);

  /* timer1 output pin Configuration */
  gpio_init_struct.gpio_pins = GPIO_PINS_8;
  gpio_init_struct.gpio_mode = GPIO_MODE_MUX;
  gpio_init_struct.gpio_out_type = GPIO_OUTPUT_PUSH_PULL;
  gpio_init_struct.gpio_pull = GPIO_PULL_NONE;
  gpio_init_struct.gpio_drive_strength = GPIO_DRIVE_STRENGTH_STRONGER;
  gpio_init(GPIOA, &gpio_init_struct);

  /* tmr1 configuration: generate 1 pwm signal using the dma burst mode:
     the tmr1clk frequency is set to system_core_clock (hz), to get tmr1 counter
     clock at 24 mhz the prescaler is computed as following:
     - prescaler = (tim1clk / tmr1 counter clock) - 1
     system_core_clock is set to 240 mhz .
     the tmr1 period is 5.86 khz: tmr1 frequency = tmr1 counter clock/(arr + 1)
                                               = 24 mhz / 4096 = 5.86khz khz
     tmr1 channel1 duty cycle = (tim1_ccr1/ tmr1_arr)* 100 = 33.33% */

  tmr_base_init(TMR1, 0xFFFF, (crm_clocks_freq_struct.sclk_freq/24000000)-1);
  tmr_cnt_dir_set(TMR1, TMR_COUNT_UP);

  /* channel 3 configuration in output mode */
  tmr_output_default_para_init(&tmr_output_struct);
  tmr_output_struct.oc_mode = TMR_OUTPUT_CONTROL_PWM_MODE_B;
  tmr_output_struct.oc_output_state = TRUE;
  tmr_output_struct.oc_polarity = TMR_OUTPUT_ACTIVE_LOW;
  tmr_output_struct.oc_idle_state = TRUE;
  tmr_output_struct.occ_output_state = FALSE;
  tmr_output_struct.occ_polarity = TMR_OUTPUT_ACTIVE_LOW;
  tmr_output_struct.occ_idle_state = FALSE;
  /* channel 3 */
  tmr_output_channel_config(TMR1, TMR_SELECT_CHANNEL_1, &tmr_output_struct);
  tmr_channel_value_set(TMR1, TMR_SELECT_CHANNEL_1, 0xFFF);

  /* enable tmr1 overflow dma request */
  tmr_dma_request_enable(TMR1, TMR_OVERFLOW_DMA_REQUEST, TRUE);
  tmr_dma_control_config(TMR1, TMR_DMA_TRANSFER_3BYTES, TMR_PR_ADDRESS);

  /* dma config for tmr1 overflow dma request */
  /* dma1 channel5 configuration */
  dma_reset(DMA1_CHANNEL5);
  dma_init_struct.buffer_size = 3;
  dma_init_struct.direction = DMA_DIR_MEMORY_TO_PERIPHERAL;
  dma_init_struct.memory_base_addr = (uint32_t)src_buffer;
  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)&TMR1->dmadt;
  dma_init_struct.peripheral_data_width = DMA_PERIPHERAL_DATA_WIDTH_HALFWORD;
  dma_init_struct.peripheral_inc_enable = FALSE;
  dma_init_struct.priority = DMA_PRIORITY_MEDIUM;
  dma_init_struct.loop_mode_enable = TRUE;
  dma_init(DMA1_CHANNEL5, &dma_init_struct);

  dma_channel_enable(DMA1_CHANNEL5, TRUE);

  /* output enable */
  tmr_output_enable(TMR1, TRUE);
  /* enable tmr1 */
  tmr_counter_enable(TMR1, TRUE);

  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。

定时器配置：设置预分频器（PSC）和重装载值（ARR），定时时间 = (PSC+1) × (ARR+1) / 时钟频率。

PWM 配置：在定时器基础上设置比较值（CCR），占空比 = CCR / (ARR+1)。CCR 越大占空比越高。

Dma_burst on CLing

AT32 TMR — DMA 突发传输

TMR — DMA 突发传输

功能简介

完整代码

代码讲解