arduino mini 为什么输出HIGH,备注却是关呢

newspaper

int ledPin = 3; // LED, connected to digital pin 3
int ledVal = 0; // value to send to pin
int wait = 20; // 20ms (.02 second) delay; shorten for faster fades
int solarPin = 0; // pin solar panel is connected to
int analogval; // value read from solarpanel
int ledState=1;

void setup()
{
Serial.begin(9600);
pinMode(ledPin, OUTPUT);
digitalWrite(ledPin, HIGH); // turn leds off
ledState=0;
delay(500);
}

void fadeDownLed()
{
digitalWrite(ledPin, LOW);
for (int i=0; i <= 255; i++)
{
analogWrite(ledPin, i);
// Serial.print("fadeDownLed ");
// Serial.println(i);
delay(20);
}
digitalWrite(ledPin, HIGH);
ledState=0;
}

newspaper

上面的代码是网上搜的。 请问红外的字体，他的标注为什么  输出HIGHT,扣面的标注却是LEDS off.

hubertdong

LED正极接电源，Arduino输出LOW时LED亮，输出HIGH时灭！

Stormer

那叫上拉电阻。有电时候表示0.

newspaper

thank you !