我如何使用IDR？

Question

我试着用按钮做一个状态机。当我按下按钮时，状态会改变。但我看不懂IDR的按钮。如何使用IDR读取按钮？如果( GPIOA->IDR |= (1U << 1) )这部分有问题，我认为还是我应该启用一些寄存器或时钟？

`

int main(void) {

    uint32_t ButtonPress = 0;

    /* Enable GPIOA clock */
    RCC->IOPENR |= (1U << 0);

    /* Setup PA0 as output */
    GPIOA->MODER &= ~(3U << 2*0);
    GPIOA->MODER |= (1U << 2*0);

    /* Setup PA1 as input */
    GPIOA->MODER &= ~(3U << 2*1);
    GPIOA->MODER |= (0U << 2*1);

    /* Setup PA1 as Button1 */
//    GPIOA->IDR |= (1U << 1);


    while(1) {

        if( GPIOA->IDR |= (1U << 1) )
            ButtonPress++;

        if(ButtonPress == 0)
            /* Turn off LED */
            GPIOA->ODR ^= (1U << 0);

        else if(ButtonPress == 1){
            /* Turn on LED 2sec interval */
            GPIOA->ODR |= (1U << 0);
            delay(LEDDELAY);
            delay(LEDDELAY);
            GPIOA->ODR ^= (1U << 0);
            delay(LEDDELAY);
            delay(LEDDELAY);
        }

        else if(ButtonPress == 2){
            /* Turn on LED 1sec interval */
            GPIOA->ODR |= (1U << 0);
            delay(LEDDELAY);
            GPIOA->ODR ^= (1U << 0);
            delay(LEDDELAY);
        }

        else if(ButtonPress == 3){
            /* Turn on LED 0.5sec interval */
            GPIOA->ODR |= (1U << 0);
            delay(LEDDELAY/2);
            GPIOA->ODR ^= (1U << 0);
            delay(LEDDELAY/2);
        }

        else if(ButtonPress == 4){
            /* Turn on LED 0.1sec interval */
            GPIOA->ODR |= (1U << 0);
            delay(LEDDELAY/10);
            GPIOA->ODR ^= (1U << 0);
            delay(LEDDELAY/10);
        }

        else if(ButtonPress == 5){
            /* Turn on LED */
            GPIOA->ODR |= (1U << 0);
        }

        else
            /* Button Reset */
            ButtonPress = 0;
    }
    return 0;
}

`

我试着用按钮做一个状态机。当我按下按钮时，状态会改变。但我看不懂IDR的按钮。

Answer 1

您正在尝试用以下行写入IDR

if( GPIOA->IDR |= (1U << 1) )

由于IDR是只读的，所以语句的计算结果总是为false.

相反，您应该使用：

if (GPIOA->IDR & GPIO_PIN_1) { // GPIO_PIN_1 is a macro for (1U << 1)
    ButtonPress++;
}

评价GPIOA针1的价值。