AT32 TMR — 输出比较翻转 (TMR3)

AT32 AT32F403A_407_Firmware_Library V2.2.2 TMR 输出比较翻转 (TMR3) 示例教学

TMR — 输出比较翻转 (TMR3)

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/oc_toggle_tmr3/src/main.c


功能简介

本示例演示输出比较模式。定时器计数到设定值时自动翻转/置高/置低引脚,可以生成精确的方波信号。

完整代码

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

int main(void)
{
  system_clock_config();

  /* peripheral clocks configuration */
  crm_configuration();

  /* nvic configuration */
  nvic_priority_group_config(NVIC_PRIORITY_GROUP_4);
  nvic_irq_enable(TMR3_GLOBAL_IRQn, 0, 0);

  /* gpio configuration */
  gpio_configuration();

  /* tmr3 configuration: output compare toggle mode:
     tmr3clk = system_core_clock / 2,
     the objective is to get tmr3 counter clock at 12 mhz:
     - prescaler = (tmr3clk / tmr3 counter clock) - 1
     cc1 update rate = tmr3 counter clock / ccr1_val = 366.2 hz
     cc2 update rate = tmr3 counter clock / ccr2_val = 732.4 hz
     cc3 update rate = tmr3 counter clock / ccr3_val = 1464.8 hz
     cc4 update rate = tmr3 counter clock / ccr4_val = 2929.6 hz */

  /* compute the prescaler value */
  prescaler_value = (uint16_t)(system_core_clock / 24000000) - 1;

  /* tmre base configuration */
  tmr_base_init(TMR3, 65535, prescaler_value);
  tmr_cnt_dir_set(TMR3, TMR_COUNT_UP);
  tmr_clock_source_div_set(TMR3, TMR_CLOCK_DIV1);

  /* output compare toggle mode configuration: channel1 */
  tmr_output_default_para_init(&tmr_oc_init_structure);
  tmr_oc_init_structure.oc_mode = TMR_OUTPUT_CONTROL_SWITCH;
  tmr_oc_init_structure.oc_idle_state = FALSE;
  tmr_oc_init_structure.oc_polarity = TMR_OUTPUT_ACTIVE_LOW;
  tmr_oc_init_structure.oc_output_state = TRUE;
  tmr_output_channel_config(TMR3, TMR_SELECT_CHANNEL_1, &tmr_oc_init_structure);
  tmr_channel_value_set(TMR3, TMR_SELECT_CHANNEL_1, ccr1_val);

  /* output compare toggle mode configuration: channel2 */
  tmr_output_channel_config(TMR3, TMR_SELECT_CHANNEL_2, &tmr_oc_init_structure);
  tmr_channel_value_set(TMR3, TMR_SELECT_CHANNEL_2, ccr2_val);

  /* output compare toggle mode configuration: channel3 */
  tmr_output_channel_config(TMR3, TMR_SELECT_CHANNEL_3, &tmr_oc_init_structure);
  tmr_channel_value_set(TMR3, TMR_SELECT_CHANNEL_3, ccr3_val);

  /* output compare toggle mode configuration: channel4 */
  tmr_output_channel_config(TMR3, TMR_SELECT_CHANNEL_4, &tmr_oc_init_structure);
  tmr_channel_value_set(TMR3, TMR_SELECT_CHANNEL_4, ccr4_val);

  /* tmr enable counter */
  tmr_counter_enable(TMR3, TRUE);

  /* tmr it enable */
  tmr_interrupt_enable(TMR3, TMR_C1_INT | TMR_C2_INT | TMR_C3_INT | TMR_C4_INT, 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。

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。

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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