[英]Arduino play midi files
I've assembled 8-bit DAC and connected it to my Arduino.我已经组装了 8 位 DAC 并将其连接到我的 Arduino。 To my DAC I connected speaker.我连接到我的 DAC 扬声器。 And now I want to know how play midi files.现在我想知道如何播放midi文件。 I found a lot of info but practically all of them using some shields.我找到了很多信息,但几乎所有信息都使用了一些盾牌。 The best I found wasthis .我发现的最好的是这个。 After reading it I copy-paste some code so it became读完后,我复制粘贴了一些代码,所以它变成了
#include <avr/pgmspace.h>
byte sample[] PROGMEM = {/*midi here*/};
int sampleSize = (sizeof(sample)-1);
int nextdata;
int sampleNUM=0;//current index
ISR(TIMER2_COMPA_vect) {
nextdata = 127;
nextdata += (127-pgm_read_byte_near(sample+sampleNUM));
if (nextdata > 255){nextdata = 255;}
else if(nextdata < 0){nextdata=0;}
PORTA = nextdata;
if (sampleNUM == sampleSize){sampleNUM = 0;}
else {sampleNUM += 1;}
}
void setup() {
DDRA = 0xFF;
cli();
TCCR2A = 0;// set entire TCCR2A register to 0
TCCR2B = 0;// same for TCCR2B
OCR2A = 249;// = (1/44100) / ((1/(16*10^6))*8) - 1
TCCR2B |= (1 << WGM12);
TCCR2B |= (1 << CS11);
TIMSK2 |= (1 << OCIE2A);
sei();//allow interrupts
}
void loop() {}
I've tried to convert music using apps from tutorial or even using that samples from tutorial but it generates only white noise我尝试使用教程中的应用程序或什至使用教程中的示例来转换音乐,但它只产生白噪声
I expect your DAC cannot drive a normal speaker load.我希望您的 DAC 无法驱动正常的扬声器负载。 (without any amplification) (无任何放大)
Further, you need a basic software-synthesizer (as @CL stated) - though I disagree, Arduino is able to handle that.此外,您需要一个基本的软件合成器(如@CL 所述)-尽管我不同意,但 Arduino 能够处理。 Although, you don't really need a DAC.虽然,您实际上并不需要 DAC。
Just use a low pass filtered pwm signal (you definetly need amplification here - a single transistor can do the trick), where the pwm base frequency has to be >2 times higher than the frequency of the tone you want to produce.只需使用低通滤波 pwm 信号(您在这里肯定需要放大 - 单个晶体管可以解决问题),其中 pwm 基频必须比您想要产生的音调频率高 2 倍以上。 The speaker itsself (mechanically, and electronically) may already be a sufficient filter, if the pwm base frequency is high如果 pwm 基频很高,扬声器本身(机械和电子)可能已经是一个足够的滤波器
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