【Follow me第二季第4期】PDM 呼吸灯

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【Follow me第二季第4期】PDM 呼吸灯 [复制链接]

# 【Follow me第二季第4期】PDM 呼吸灯

本文介绍 **选做任务一** 的完成，即

通过RGB LED不同颜色、亮度显示PDM麦克风收到的声音大小。

主要分为两部分，首先实现 RGB LED 呼吸灯，之后结合 PDM 传感器实现声控彩色 LED。

## 呼吸灯

根据 Arduino Nano RP2040 Connect 开发板原理图可知，板载 RGB LED 为低电平点亮

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### 实现思路

利用正弦波信号和 `analogWrite` 函数实现三色 LED 的亮度循环变化，以达到 **呼吸** 效果。

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### 代码

```c++
#include "WiFiNINA.h"

#define led1 LEDR
#define led2 LEDG
#define led3 LEDB

float angle1;
float angle2;
float angle3;

void setup() {
pinMode(led1, OUTPUT);
pinMode(led2, OUTPUT);
pinMode(led3, OUTPUT);

angle1 = 0.0;
angle2 = 0.0 + PI/3.0;
angle3 = 0.0 + 2.0*PI/3.0;
}

void loop() {
angle1 += 0.01;
angle2 += 0.01;
angle3 += 0.01;

if(angle1 >= PI)
  angle1 -= PI;
if(angle2 >= PI)
  angle2 -= PI;
if(angle3 >= PI)
  angle3 -= PI;

int a = sin(angle1)*255;
int b = sin(angle2)*255;
int c = sin(angle3)*255;

analogWrite(led1, a);
analogWrite(led2, b);
analogWrite(led3, c);
delay(5);
}
```

#### 流程图

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### 效果

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## PDM 呼吸灯

将 PDM 麦克风传感器采集到的信号数据，替换前面的呼吸灯正弦信号。

### 代码

```c++
#include "WiFiNINA.h"
#include <PDM.h>

#define led1 LEDR
#define led2 LEDG
#define led3 LEDB

float angle1;
float angle2;
float angle3;

static const char channels = 1;
static const int frequency = 16000;
short sampleBuffer[512];
volatile int samplesRead;

void setup() {
pinMode(led1, OUTPUT);
pinMode(led2, OUTPUT);
pinMode(led3, OUTPUT);

Serial.begin(9600);
while (!Serial);

PDM.onReceive(onPDMdata);

if (!PDM.begin(channels, frequency)) {
  Serial.println("Failed to start PDM!");
  while (1);
}
}

void loop() {
if (samplesRead) {
  for (int i = 0; i < samplesRead; i++) 
  {
  //Serial.println(sampleBuffer<i>);
  int Frq = map(sampleBuffer<i>, 0, 20000, 0, 16000);
  Serial.println(Frq);
  int a = 255 - (sampleBuffer<i>/10000)*255;
  int b = 255 - (sampleBuffer<i>/10000)*255;
  int c = 255 - (sampleBuffer<i>/10000)*255;
  analogWrite(led1, a);
  analogWrite(led2, b);
  analogWrite(led3, c);
  }
  samplesRead = 0;
}
}

void onPDMdata() {
int bytesAvailable = PDM.available();
PDM.read(sampleBuffer, bytesAvailable);
samplesRead = bytesAvailable / 2;
}
```

这里使用音频文件 `alarm1.mp3` 的测试数据，将其信号强度归一化，作为 LED 亮度的基准。

#### 流程图

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### 效果

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可以看出，LED 随声音的信号强度变化，亮度发生变化。