使用PWM生成基本的钢琴音符
2016-12-021.9万
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本文介绍了如何使用Arduino Uno、蜂鸣器和4*4矩阵键盘，通过PWM生成基本的钢琴音符。项目包括详细的电路图和代码示例，适合STEM教育场景。通过配置TCCR2A和TCCR2B寄存器，可以精确控制PWM频率，生成特定音符。例如，生成261Hz的C音符，配置为TCCR2A = B01000011, TCCR2B = B00001110, OCR2A = 119。上传代码后，用户可以尝试弹奏“生日快乐”等简单曲目。
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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）  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  piano.zip |
