Arduino learning——Digital IO-优快云博客

本文链接：https://blog.youkuaiyun.com/aaartemis/article/details/102500254

本文详细介绍了Arduino中数字输入和输出的基本概念，包括pinMode()和digitalWrite()函数的使用，以及INPUT、OUTPUT和INPUT_PULLUP模式的区别。通过实例解释了如何设置Arduino引脚为输入或输出，并如何读取和写入数字信号。

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pinMode()

arduino pins can provide current or absorb current up to 40 mA of current to other devices/circuits.

Descrpition

Choose a pin to be in input mode or in output mode or in INPUT_PULLUP. it will return nothing.

syntax

pinMode(pin, mode);//pin number and the mode should be setted
//pin:the pin number of the pin on your arduino
//mode:INPUT, OUTPUT, or INPUT_PULLUP

INPUT

the INPUT mode in pinMode().

definition

It is just like putting a very large series resistor. in this way, the pin will be perfect to be used for reading a sensor.

pinMode(pin, INPUT);

INPUT_PULLUP

the INPUT_PULLUP mode in pinMode().

definition

there is really a very large series resistor in some of the arduino pins. By setting the mode in INPUT_PULLUP, you don’t need to add a external pull-up resistors in your electrical network for safety.

pinMode(pin, INPUT_PULLUP);

OUTPUT

the OUTPUT mode in pinMode()

definition

when the pin is setted unto this mode, it can provide a substantial amount of current to other circuits.

pinMode(pin, OUTPUT);

digitalWrite()

Description

Read the value of a digital pin, and it will return HIGH or LOW.

Syntax

digitalRead(pin);//pin number should be setted

Warning

digitalRead() will return randomly if the pin isn’t connected to anything

HIGH

the meaning of HIGH is different depending on the pin is set to an INPUT or OUTPUT.

when the pin is in INPUT mode

the voltage is larger than a certain number, then it will return HIGH by using digitRead().
when it is written to be HIGH by digitalWrite(), the internal resistor will be pull up.

when the pi is in OUTPUT mode

when the pin in in OUTPUT mode, and is set to be in high volts.

LOW

The meaning of LOW also has a different meaning depending on whether a pin is set to INPUT or OUTPUT.

when the pin is in INPUT mode

when the pin is set in INPUT mode and the voltage is lower than a certain number, it will return LOW by using digitalRead().

when the pin is in OUTPUT mode

when the pin is set in OUYPUT and it is set to LOW using digitalWrite(), the pin can sink current.

digitalWrite()

description

Write a HIGH or a LOW value to a digital pin
If the pin has been configured as an OUTPUT with pinMode(), its voltage will be set to a certain value.
If the pin is configured as an INPUT, digitalWrite() will enable (HIGH) or disable (LOW) the internal pullup on the input pin.

it will return nothing

syntax

digitalWrite(pin, value);//the pin number and the value should be set.

reference: arduino language reference