c - 如何在 C 中按下按键退出 time_delay 循环？

Question

我的程序正在通过 7 个不同的 channel 读取 ADC 值。我设置了一个计时器，它按顺序读取每个 channel 。我想无限地运行这个计时器(但现在我将其设置为一个小时)并且能够通过按键(例如 q )退出计时器。我必须插入 if 和 while 循环来查找 getchar()==q，但每个循环都会暂停程序，直到我实际按下 q 然后它会读取下一行并重复。如果有人能帮助我在按键时退出计时器，我将不胜感激。谢谢

static void ch0
{
    send_receive_LTC1859 (0x00, 0x00, 0, spifd);
}

//Here CH 1-6 go (saving space for readers)

static void ch7
{
    send_receive_LTC1859 (0xF0, 0x08, 0, spifd);    
    printf("\n");

//Look for quit key
}

uint32 accel_testing (){

    spifd = fopen("spi2:", 0);
    printf("Accel names\n");

    MQX_TICK_STRUCT ticks;
    MQX_TICK_STRUCT dticks;
    _timer_id       read_ch0;
    _timer_id       read_ch2;
    _timer_id       read_ch3;
    _timer_id       read_ch4;
    _timer_id       read_ch5;
    _timer_id       read_ch6;
    _timer_id       read_ch7;

    _timer_create_component(TIMER_TASK_PRIORITY, TIMER_STACK_SIZE);
    _time_init_ticks(&dticks, 0);
    _time_add_msec_to_ticks(&dticks,500);

    _time_get_elapsed_ticks(&ticks);
    read_ch0 = _timer_start_periodic_at_ticks(ch0, 0, 
       TIMER_ELAPSED_TIME_MODE, &ticks, &dticks);
    _time_add_msec_to_ticks(&ticks, 5);
    read_ch2 = _timer_start_periodic_at_ticks(ch2, 0, 
       TIMER_ELAPSED_TIME_MODE, &ticks, &dticks);
    _time_add_msec_to_ticks(&ticks, 5);
    read_ch3 = _timer_start_periodic_at_ticks(ch3, 0, 
       TIMER_ELAPSED_TIME_MODE, &ticks, &dticks);
    _time_add_msec_to_ticks(&ticks, 5);
    read_ch4 = _timer_start_periodic_at_ticks(ch4, 0, 
       TIMER_ELAPSED_TIME_MODE, &ticks, &dticks);
    _time_add_msec_to_ticks(&ticks, 5);
    read_ch5 = _timer_start_periodic_at_ticks(ch5, 0, 
       TIMER_ELAPSED_TIME_MODE, &ticks, &dticks);
    _time_add_msec_to_ticks(&ticks, 5);
    read_ch6 = _timer_start_periodic_at_ticks(ch6, 0, 
       TIMER_ELAPSED_TIME_MODE, &ticks, &dticks);
    _time_add_msec_to_ticks(&ticks, 5);
    read_ch7 = _timer_start_periodic_at_ticks(ch7, 0, 
       TIMER_ELAPSED_TIME_MODE, &ticks, &dticks);
    _time_add_msec_to_ticks(&ticks, 5);

    _time_delay(3600000); // wait 1 hour
    printf("\nThe task is finished!\n");

    _timer_cancel(read_ch0);
    _timer_cancel(read_ch2);
    _timer_cancel(read_ch3);
    _timer_cancel(read_ch4);
    _timer_cancel(read_ch5);
    _timer_cancel(read_ch6);
    _timer_cancel(read_ch7);

return 0;

}

Answer 1

如果您使用的是 Linux，那么 select() 将会有所帮助。

#include <errno.h>
#include <stdio.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/time.h>
int
input_timeout (int filedes, unsigned int seconds)
{
  fd_set set;
  struct timeval timeout;
  /* Initialize the file descriptor set. */
  FD_ZERO (&set);
  FD_SET (filedes, &set);

  /* Initialize the timeout data structure. */
  timeout.tv_sec = seconds;
  timeout.tv_usec = 0;

  /* select returns 0 if timeout, 1 if input available, -1 if error. */
  return TEMP_FAILURE_RETRY (select (FD_SETSIZE,
                                     &set, NULL, NULL,
                                     &timeout));
}
int
main (void)
{
  fprintf (stdin, "select returned %d.\n",
           input_timeout (STDIN_FILENO, 5));
  return 0;
}