我怎样才能digitalRead针是在pinMode OUTPUT？ [英] How can I digitalRead a pin that is in pinMode OUTPUT?

问题描述

我有一个非常简单的测试草图在我试图引脚设置为 HIGH ，然后读取它与 digitalRead 。这里是我的草图。

I have a very simple test sketch in which I'm trying to set a pin to HIGH and then read its state with digitalRead. Here is my sketch.

void setup()
{
    Serial.begin(9600);
}

void loop()
{
    delay(1000);

    pinMode(3, OUTPUT);
    digitalWrite(3, HIGH);
    delay(1000);

    pinMode(3, INPUT);
    Serial.println(digitalRead(3));
}

串行监测结果：

0
0
0
0

我已经认识到，改变pinMode将被 HIGH 停止。因此，设置引脚 HIGH 在输出模式，然后更改为输入模式将其更改为 LOW 。所以digitalRead将始终返回0。如果我不改变pinMode它将不能够读取的销。所以，我怎么能读引脚在输出模式不失价值？的当前设置

I have come to understand that changing the pinMode will stop it from being HIGH. So setting a pin to HIGH in OUTPUT mode and then changing to INPUT mode will change it to LOW. So the digitalRead will always return 0. If I don't change the pinMode it won't be able to read the pin. So how can I read the current setting of a pin that is in OUTPUT mode without losing the value?

推荐答案

在这种情况下，你只是想访问数据注册。

In this case you just want to access the data register itself.

PORTB和PORTD寄存器包含你正在寻找的针数据。我终于获得一个Arduino弄明白。要使用 bitRead（PORTD，针）。

PORTB and PORTD registers contain the pin data you are looking for. I finally got access to an Arduino to figure it out. You want to use bitRead(PORTD, pin).

Serial.println(bitRead(PORTD,3)); //Reads bit 3 of register PORTD which contains the current state (high/low) of pin 3.

读操作了解详情。

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