TMR — 定时器 DMA 触发

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#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_10;
  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);

  gpio_init_struct.gpio_pins = GPIO_PINS_15;
  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(GPIOB, &gpio_init_struct);

  /* tmr1 dma transfer example
  tmr1clk = system_core_clock, prescaler = 0, tmr1 counter clock = system_core_clock
  system_core_clock is set to 240 mhz.

  the objective is to configure tmr1 channel 3 to generate complementary pwm
  signal with a frequency equal to 17.57 khz:
     - tmr1_period = (system_core_clock / 17570) - 1
  and a variable duty cycle that is changed by the dma after a specific number of
  update dma request.

  the number of this repetitive requests is defined by the tmr1 repetition counter,
  each 3 update requests, the tmr1 channel 3 duty cycle changes to the next new
  value defined by the src_buffer. */
  /* compute the value to be set in arr regiter to generate signal frequency at 17.57 khz */
  timer_period = (crm_clocks_freq_struct.sclk_freq / 17570 ) - 1;
  /* compute c1dt value to generate a duty cycle at 50% */
  src_buffer[0] = (uint16_t) (((uint32_t) 5 * (timer_period - 1)) / 10);
  /* compute c1dt value to generate a duty cycle at 37.5% */
  src_buffer[1] = (uint16_t) (((uint32_t) 375 * (timer_period - 1)) / 1000);
  /* compute c1dt value to generate a duty cycle at 25% */
  src_buffer[2] = (uint16_t) (((uint32_t) 25 * (timer_period - 1)) / 100);

  tmr_base_init(TMR1, timer_period, 0);
  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 = TRUE;
  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_3, &tmr_output_struct);
  tmr_channel_value_set(TMR1, TMR_SELECT_CHANNEL_3, src_buffer[0]);

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

  /* 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->c3dt;
  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)
  {
  }
}