使用PWM生成基本的钢琴音符 DF创客社区

本帖最后由 yuzhunyu 于 2016-12-2 11:32 编辑

所需硬件：1.  Arduino uno *1
               2.  蜂鸣器             *1
               3.  4*4矩阵键盘    *1
电路图：
蜂鸣器接在11号口，矩阵键盘占用2-9号口（r0、r1、r2、r3、c0、c1、c2、c3）
使用PWM生成基本的钢琴音符图1

代码：
[mw_shl_code=applescript,true]#define c3 9
#define c2 8
#define c1 7
#define c0 6
#define r3 5
#define r2 4
#define r1 3
#define r0 2
void setup() {
  Serial.begin(9600);
  pinMode(c0, INPUT_PULLUP);
  pinMode(c1, INPUT_PULLUP);
  pinMode(c2, INPUT_PULLUP);
  pinMode(c3, INPUT_PULLUP);
  pinMode(r0, OUTPUT);
  pinMode(r1, OUTPUT);
  pinMode(r2, OUTPUT);
  pinMode(r3, OUTPUT);
  pinMode(11, OUTPUT);
}
void loop() {
  digitalWrite(r0, LOW);
  digitalWrite(r1, HIGH);
  digitalWrite(r2, HIGH);
  digitalWrite(r3, HIGH);
  if (digitalRead(c0) == LOW) {
TCCR2A = B01000011;
TCCR2B = B00001110;
OCR2A = 119;
delay(100);
TCCR2B = B00001000;
TCCR2A = B00000000;
digitalWrite(11, LOW);
  }
  else if (digitalRead(c1) == LOW) {
TCCR2A = B01000011;
TCCR2B = B00001110;
OCR2A = 106;
delay(100);
TCCR2B = B00001000;
TCCR2A = B00000000;
digitalWrite(11, LOW);
  }
  else if (digitalRead(c2) == LOW) {
TCCR2A = B01000011;
TCCR2B = B00001110;
OCR2A = 94;
delay(100);
TCCR2B = B00001000;
TCCR2A = B00000000;
digitalWrite(11, LOW);
  }
  else if (digitalRead(c3) == LOW) {
TCCR2A = B01000011;
TCCR2B = B00001110;
OCR2A = 89;
delay(100);
TCCR2B = B00001000;
TCCR2A = B00000000;
digitalWrite(11, LOW);
  }
  digitalWrite(r0, HIGH);
  digitalWrite(r1, LOW);
  digitalWrite(r2, HIGH);
  digitalWrite(r3, HIGH);
  if (digitalRead(c0) == LOW) {
TCCR2A = B01000011;
TCCR2B = B00001110;
OCR2A = 79;
delay(100);
TCCR2B = B00001000;
TCCR2A = B00000000;
digitalWrite(11, LOW);
  }
  else if (digitalRead(c1) == LOW) {
TCCR2A = B01000011;
TCCR2B = B00001110;
OCR2A = 71;
delay(100);
TCCR2B = B00001000;
TCCR2A = B00000000;
digitalWrite(11, LOW);
  }
  else if (digitalRead(c2) == LOW) {
TCCR2A = B01000011;
TCCR2B = B00001110;
OCR2A = 63;
delay(100);
TCCR2B = B00001000;
TCCR2A = B00000000;
digitalWrite(11, LOW);
  }
  else if (digitalRead(c3) == LOW) {
TCCR2A = B01000011;
TCCR2B = B00001110;
OCR2A = 59;
delay(100);
TCCR2B = B00001000;
TCCR2A = B00000000;
digitalWrite(11, LOW);
  }
  digitalWrite(r0, HIGH);
  digitalWrite(r1, HIGH);
  digitalWrite(r2, LOW);
  digitalWrite(r3, HIGH);
  if (digitalRead(c0) == LOW) {
TCCR2A = B01000011;
TCCR2B = B00001110;
OCR2A = 25;
delay(100);
TCCR2B = B00001000;
TCCR2A = B00000000;
digitalWrite(11, LOW);
  }
  else if (digitalRead(c1) == LOW) {
TCCR2A = B01000011;
TCCR2B = B00001110;
OCR2A = 20;
delay(100);
TCCR2B = B00001000;
TCCR2A = B00000000;
digitalWrite(11, LOW);
  }
  else if (digitalRead(c2) == LOW) {
TCCR2A = B01000011;
TCCR2B = B00001110;
OCR2A = 10;
delay(100);
TCCR2B = B00001000;
TCCR2A = B00000000;
digitalWrite(11, LOW);
  }
  else if (digitalRead(c3) == LOW) {
TCCR2A = B01000011;
TCCR2B = B00001110;
OCR2A = 50;
delay(100);
TCCR2B = B00001000;
TCCR2A = B00000000;
digitalWrite(11, LOW);
  }
  digitalWrite(r0, HIGH);
  digitalWrite(r1, HIGH);
  digitalWrite(r2, HIGH);
  digitalWrite(r3, LOW);
  if (digitalRead(c0) == LOW) {
TCCR2A = B01000011;
TCCR2B = B00001110;
OCR2A = 50;
delay(100);
TCCR2B = B00001000;
TCCR2A = B00000000;
digitalWrite(11, LOW);
  }
  else if (digitalRead(c1) == LOW) {
TCCR2A = B01000011;
TCCR2B = B00001110;
OCR2A = 50;
delay(100);
TCCR2B = B00001000;
TCCR2A = B00000000;
digitalWrite(11, LOW);
  }
  else if (digitalRead(c2) == LOW) {
TCCR2A = B01000011;
TCCR2B = B00001110;
OCR2A = 50;
delay(100);
TCCR2B = B00001000;
TCCR2A = B00000000;
digitalWrite(11, LOW);
  }
  else if (digitalRead(c3) == LOW) {
TCCR2A = B01000011;
TCCR2B = B00001110;
OCR2A = 50;
delay(100);
TCCR2B = B00001000;
TCCR2A = B00000000;
digitalWrite(11, LOW);
  }
}[/mw_shl_code]
原理：
钢琴的基本音符的频率如下
c - 261 HZ
d - 294 HZ
e - 329 HZ
f - 349 HZ
g - 392 HZ
a - 440 HZ
b - 493 HZ
C - 523 HZ
涉及到的公式：
frequency in Hz = 16MHz/prescalar/(OCRA+1)/2 (for register A i.e. pin 11)
比如：生成261hz
TCCR2A = B01000011; (com2a1 com2a0计数器值达到119)
TCCR2B = B00001110; （ca22 ca21 cs20 prescalar选择256)
OCR2A = 119;
代入公式得:16MHZ/256/120/2 = 260.42HZ

上传至UNO，现在你可以试试自己弹一曲“生日快乐”了:lol
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