c - 读取引脚上的输入(Teensy)

Question

我开始摆弄 Teensy 2，并学习 C 代码。目前我正在尝试弄清楚如何将引脚设置作为输入。我的代码如下:

#include <avr/io.h>
#include <avr/pgmspace.h>
#include "usb_debug_only.h"
#include "print.h"
#include <util/delay.h>

#define RED_LED_ON  (PORTB |= (1<<7))
#define RED_LED_OFF  (PORTB &= ~(1<<7))

#define GREEN_LED_ON  (PORTD |= (1<<2))
#define GREEN_LED_OFF  (PORTD &= ~(1<<2))

#define BLUE_LED_ON  (PORTC |= (1<<7))
#define BLUE_LED_OFF  (PORTC &= ~(1<<7))

#define SWITCH_OUT_CONFIG (DDRD |= (1<<6), PORTD |= (1<<6))

#define SWITCH_IN_CONFIG (DDRF &= ~(1<<1), PORTF |= (1<<1))

#define LED_CONFIG  (DDRB |= (1<<0))
#define CPU_PRESCALE(n) (CLKPR = 0x80, CLKPR = (n))

#define MY_DELAY 100

int main(void) {
    // set for 16 MHz clock, and make sure the LED is off
    CPU_PRESCALE(0);
    LED_CONFIG;
    /*SWITCH_IN_CONFIG;
    SWITCH_OUT_CONFIG;*/

    DDRD |= (1<<6); //Set pin D6 as output
    DDRF &= ~(1<<1); //Set pin F1 as input

    PORTD |= (1<<6); //Set pin D6 output to high
    PORTF |= (1<<1); //Set pin F1 to act as pullup resistor

    RED_LED_OFF;
    GREEN_LED_OFF;
    BLUE_LED_OFF;

    // initialize the USB, but don't want for the host to
    // configure.  The first several messages sent will be
    // lost because the PC hasn't configured the USB yet,
    // but we care more about blinking than debug messages!
    usb_init();

    for(;;) {
        if(PINF & (1<<1)) {
            /*Do stuff here, since button is pushed*/
    }
    else {
        /*Do nothing*/
    }
}

}

我当前遇到的问题是我的输入 (F1) 没有完成电路。我把它连接到一个按钮。当我将该按钮直接接地时，电路就完成了，并且当我按下按钮时，它所连接的 LED 将会亮起。当我将连接切换到该引脚时，它什么也没做。据我目前所知(这似乎是不正确的)，当连接到另一个输出高信号的引脚(在本例中为 D6，我知道它正在工作，因为我可以在按钮电路中使用它)时，该引脚应该读为高电平。当它接地时)。相反，它所连接的寄存器中该引脚的值似乎始终为“1”(if else 语句的“do stuff”部分始终运行)。

任何有关我所犯错误的帮助将不胜感激!

Answer 1

您讨论并配置端口 F 上的输入，但您从 PINB 寄存器读取端口 B。

想必，您应该阅读PINF。