TIM - 通用定时器

void TIM_Configuration(void)
{
    GPIO_InitTypeDef        GPIO_InitStructure;
    TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;
    TIM_OCInitTypeDef       TIM_OCInitStructure;

    /* 开启 TIM3 及 GPIOA/AFIO 时钟 */
    RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM3, ENABLE);
    RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA | RCC_APB2Periph_AFIO, ENABLE);

    /* PA7: TIM3_CH2 → 复用推挽输出 */
    GPIO_InitStructure.GPIO_Pin   = GPIO_Pin_7;
    GPIO_InitStructure.GPIO_Mode  = GPIO_Mode_AF_PP;
    GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
    GPIO_Init(GPIOA, &GPIO_InitStructure);

    /* 时基：PSC 使 CK_CNT=1MHz，ARR=99 → PWM 周期 100μs（10kHz） */
    TIM_TimeBaseStructure.TIM_Period        = 99;
    TIM_TimeBaseStructure.TIM_Prescaler     = clocks.PCLK1_Frequency / 1000000 - 1;
    TIM_TimeBaseStructure.TIM_ClockDivision = TIM_CKD_DIV1;
    TIM_TimeBaseStructure.TIM_CounterMode   = TIM_CounterMode_Up;
    TIM_TimeBaseInit(TIM3, &TIM_TimeBaseStructure);

    /* 输出比较：PWM2 模式，CH2，Pulse=49 → 占空比 49%，低电平有效 */
    TIM_OCInitStructure.TIM_OCMode       = TIM_OCMode_PWM2;
    TIM_OCInitStructure.TIM_OutputState  = TIM_OutputState_Enable;
    TIM_OCInitStructure.TIM_OutputNState = TIM_OutputNState_Enable;
    TIM_OCInitStructure.TIM_Pulse        = 99 / 2;
    TIM_OCInitStructure.TIM_OCPolarity   = TIM_OCPolarity_Low;
    TIM_OCInitStructure.TIM_OCNPolarity  = TIM_OCNPolarity_Low;
    TIM_OCInitStructure.TIM_OCIdleState  = TIM_OCIdleState_Set;
    TIM_OCInitStructure.TIM_OCNIdleState = TIM_OCIdleState_Reset;
    TIM_OC2Init(TIM3, &TIM_OCInitStructure);

    /* 使能预装载寄存器：运行中改 CCR/ARR 会在下个更新事件生效 */
    TIM_OC2PreloadConfig(TIM3, TIM_OCPreload_Enable);
    TIM_ARRPreloadConfig(TIM3, ENABLE);

    /* 启动定时器 */
    TIM_Cmd(TIM3, ENABLE);
    TIM_CtrlPWMOutputs(TIM3, ENABLE);
}

RCC_ClocksTypeDef clocks;

int main(void)
{
    delay_init();
    UART_Configuration(115200);
    RCC_GetClocksFreq(&clocks);

    printf("SYSCLK: %3.1fMhz, HCLK: %3.1fMhz, PCLK1: %3.1fMhz, "
           "PCLK2: %3.1fMhz, ADCCLK: %3.1fMhz\n",
           (float)clocks.SYSCLK_Frequency / 1000000,
           (float)clocks.HCLK_Frequency / 1000000,
           (float)clocks.PCLK1_Frequency / 1000000,
           (float)clocks.PCLK2_Frequency / 1000000,
           (float)clocks.ADCCLK_Frequency / 1000000);
    printf("TIM General PWM Test.\n");

    TIM_Configuration();

    while (1);
}

int SER_PutChar(int ch)
{
    while (!USART_GetFlagStatus(USART_TEST, USART_FLAG_TC));
    USART_SendData(USART_TEST, (uint8_t)ch);
    return ch;
}

int fputc(int c, FILE *f)
{
    if (c == '\n')
        SER_PutChar('\r');         // 补回车，确保串口工具正确换行
    return (SER_PutChar(c));
}

void TIM_ICConfiguration(void)
{
    GPIO_InitTypeDef        GPIO_InitStructure;
    TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;
    TIM_ICInitTypeDef       TIM_ICInitStructure;
    NVIC_InitTypeDef        NVIC_InitStructure;

    RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM3, ENABLE);
    RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA | RCC_APB2Periph_AFIO, ENABLE);

    /* PA7: TIM3_CH2 → 下拉输入（捕获外部信号） */
    GPIO_InitStructure.GPIO_Pin  = GPIO_Pin_7;
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IPD;
    GPIO_Init(GPIOA, &GPIO_InitStructure);

    /* 时基：PSC=71（72MHz/72=1MHz，计数分辨率 1μs），ARR=0xFFFF */
    TIM_TimeBaseStructure.TIM_Period        = 0xFFFF;
    TIM_TimeBaseStructure.TIM_Prescaler     = 72 - 1;
    TIM_TimeBaseStructure.TIM_ClockDivision = TIM_CKD_DIV1;
    TIM_TimeBaseStructure.TIM_CounterMode   = TIM_CounterMode_Up;
    TIM_TimeBaseInit(TIM3, &TIM_TimeBaseStructure);

    /* 通道2 上升沿捕获 */
    TIM_ICInitStructure.TIM_Channel     = TIM_Channel_2;
    TIM_ICInitStructure.TIM_ICPolarity  = TIM_ICPolarity_Rising;
    TIM_ICInitStructure.TIM_ICSelection = TIM_ICSelection_DirectTI;
    TIM_ICInitStructure.TIM_ICPrescaler = TIM_ICPSC_Div1;
    TIM_ICInitStructure.TIM_ICFilter    = 0x0;
    TIM_ICInit(TIM3, &TIM_ICInitStructure);

    /* NVIC：溢出 + 捕获中断 */
    NVIC_InitStructure.NVIC_IRQChannel                   = TIM3_IRQn;
    NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0;
    NVIC_InitStructure.NVIC_IRQChannelSubPriority        = 3;
    NVIC_InitStructure.NVIC_IRQChannelCmd                = ENABLE;
    NVIC_Init(&NVIC_InitStructure);
    TIM_ITConfig(TIM3, TIM_IT_Update | TIM_IT_CC2, ENABLE);

    TIM_Cmd(TIM3, ENABLE);
}

void TIM3_IRQHandler(void)
{
    if (!(TIM3_CAPTURE_STA & 0x80))   /* 未完成捕获 */
    {
        /* 处理溢出中断 */
        if (TIM_GetITStatus(TIM3, TIM_IT_Update))
        {
            if (TIM3_CAPTURE_STA & 0x40)   /* 已捕获上升沿，统计溢出 */
            {
                if ((TIM3_CAPTURE_STA & 0x3F) == 0x3F)
                    TIM3_CAPTURE_STA |= 0x80;   /* 溢出 32 次，标记失败 */
                else
                    TIM3_CAPTURE_STA++;          /* 溢出次数 +1 */
            }
        }

        /* 处理捕获中断（CH2） */
        if (TIM_GetITStatus(TIM3, TIM_IT_CC2))
        {
            if (TIM3_CAPTURE_STA & 0x40)   /* 已捕获上升沿，本次为下降沿 */
            {
                TIM3_CAPTURE_VAL = TIM_GetCapture2(TIM3);   /* 读取计数值 */
                TIM3_CAPTURE_STA |= 0x80;                    /* 标记完成 */
                TIM_OC2PolarityConfig(TIM3, TIM_ICPolarity_Rising);  /* 切回上升沿 */
            }
            else                            /* 首次捕获上升沿 */
            {
                TIM3_CAPTURE_STA = 0x40;                    /* 标记已捕获上升沿 */
                TIM_SetCounter(TIM3, 0);                     /* 计数器清零 */
                TIM_OC2PolarityConfig(TIM3, TIM_ICPolarity_Falling); /* 切为下降沿 */
            }
        }
    }
    TIM_ClearITPendingBit(TIM3, TIM_IT_CC2 | TIM_IT_Update);   /* 清除中断标志 */
}