AT32 TMR — 门控模式

AT32 AT32F403A_407_Firmware_Library V2.2.2 TMR 门控模式 示例教学

TMR — 门控模式

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/hang_mode/src/main.c


功能简介

本示例演示定时器的基本用法。定时器是 MCU 最灵活的外设之一,可以实现定时、PWM、输入捕获、编码器等多种功能。

完整代码

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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 clock */
  crm_periph_clock_enable(CRM_TMR1_PERIPH_CLOCK, TRUE);
  crm_periph_clock_enable(CRM_GPIOA_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);

  gpio_init_struct.gpio_pins = GPIO_PINS_9;
  gpio_init_struct.gpio_mode = GPIO_MODE_INPUT;
  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);

  /* hang mode test
    1/tmr1 is configured as master timer:
     - toggle mode is used

    2/tmr1 is configured as slave timer for an external trigger connected
     to tmr1 ti2 pin (tmr1 ch2 configured as input pin):
     - the tmr1 ti2fp2 is used as trigger input
     - rising edge is used to start and stop the tmr1: hang mode.

    * the timxclk is fixed to 240 mhz, the prescaler is equal to 2 so the tmrx clock
      counter is equal to 80 mhz.
      the three timers are running at:
      tmrx frequency = tmrx clock counter/ 2*(timx_period + 1) = 500 khz.
  */

  /* tmr2 and tmr3 counter mode configuration */
  tmr_base_init(TMR1, 79, 2);
  tmr_cnt_dir_set(TMR1, TMR_COUNT_UP);

  /* tmr1 output mode configuration */
  tmr_output_default_para_init(&tmr_output_struct);
  tmr_output_struct.oc_mode = TMR_OUTPUT_CONTROL_SWITCH;
  tmr_output_struct.oc_output_state = TRUE;
  tmr_output_struct.oc_polarity = TMR_OUTPUT_ACTIVE_HIGH;
  tmr_output_struct.oc_idle_state = TRUE;
  tmr_output_struct.occ_output_state = FALSE;
  tmr_output_struct.occ_polarity = TMR_OUTPUT_ACTIVE_HIGH;
  tmr_output_struct.occ_idle_state = FALSE;
  /* tmr1 channel 1 */
  tmr_output_channel_config(TMR1, TMR_SELECT_CHANNEL_1, &tmr_output_struct);
  tmr_channel_value_set(TMR1, TMR_SELECT_CHANNEL_1, 40);

  /* configure tmr1 channel2 to get hang signal */
  tmr_input_default_para_init(&tmr_input_config_struct);
  tmr_input_config_struct.input_channel_select = TMR_SELECT_CHANNEL_2;
  tmr_input_config_struct.input_mapped_select = TMR_CC_CHANNEL_MAPPED_DIRECT;
  tmr_input_config_struct.input_polarity_select = TMR_INPUT_RISING_EDGE;
  tmr_input_channel_init(TMR1, &tmr_input_config_struct, TMR_CHANNEL_INPUT_DIV_1);

  /* select the tmr1 input trigger: C2IF2 */
  tmr_trigger_input_select(TMR1, TMR_SUB_INPUT_SEL_C2DF2);

  /* select the slave mode: hang mode */
  tmr_sub_mode_select(TMR1, TMR_SUB_HANG_MODE);

  /* 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。

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。

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