barGraph

# はじめに

アナログセンサから読み取った値に応じて、10個のLEDを光らせます。

アナログの0番ピンにセンサが、デジタルピンの2番ピンから11番ピンにLEDが接続されている想定です。

# プログラム

## 定義等

 `````` 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 `````` ``````/* LED bar graph Turns on a series of LEDs based on the value of an analog sensor. This is a simple way to make a bar graph display. Though this graph uses 10 LEDs, you can use any number by changing the LED count and the pins in the array. This method can be used to control any series of digital outputs that depends on an analog input. The circuit: - LEDs from pins 2 through 11 to ground created 4 Sep 2010 by Tom Igoe This example code is in the public domain. https://www.arduino.cc/en/Tutorial/BuiltInExamples/BarGraph */ // these constants won't change: const int analogPin = A0; // the pin that the potentiometer is attached to const int ledCount = 10; // the number of LEDs in the bar graph int ledPins[] = { 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 }; // an array of pin numbers to which LEDs are attached ``````

const int型の変数analogPinとledCountを定義し初期化します。

int型の配列ledPinsを定義し初期化します。

## setup()

 ``````32 33 34 35 36 37 38 `````` ``````void setup() { // loop over the pin array and set them all to output: for (int thisLed = 0; thisLed < ledCount; thisLed++) { pinMode(ledPins[thisLed], OUTPUT); } } ``````

for文を使って、thisLedを0から9まで変化させ、デジタルのledPins[thisLed]番ピンをpinMode()を使い、出力モードにします。結果として、デジタルピンの2番から11番までが出力モードになります。

## loop()

 ``````39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 `````` ``````void loop() { // read the potentiometer: int sensorReading = analogRead(analogPin); // map the result to a range from 0 to the number of LEDs: int ledLevel = map(sensorReading, 0, 1023, 0, ledCount); // loop over the LED array: for (int thisLed = 0; thisLed < ledCount; thisLed++) { // if the array element's index is less than ledLevel, // turn the pin for this element on: if (thisLed < ledLevel) { digitalWrite(ledPins[thisLed], HIGH); } // turn off all pins higher than the ledLevel: else { digitalWrite(ledPins[thisLed], LOW); } } }``````