从模式输入捕获

1，Reset Mode + TI1FP1 + 直接输入捕获

2，不用开启中断；

3，HAL_TIM_IC_Start(&htim15,TIM_CHANNEL_1);

char biff[30];
void LOOP()
{
    float frqq=1e6/(HAL_TIM_ReadCapturedValue(&htim15,TIM_CHANNEL_1)+1);
    sprintf(biff,"   FRQQ:%.0fHz       ",frqq);
    LCD_DisplayStringLine(Line4,(u8*)biff);
}