【Arduino 动手做】在 VFD 显示屏上 DIY 音频频谱分析仪
频谱分析仪是一种测量工具，可显示传入音频信号的实时频率分析。它通常是均衡器和音频信号处理设备的组成部分。纵轴表示以分贝为单位测量的特定频率的振幅。
这次我将向您展示如何在 20x2 VFD 显示屏上制作这样的设备。在我之前的某个视频中，您可以看到如何在这样的显示屏上制作音量表。这些显示屏的优点在于它们发出非常明亮的光线，对比度高，并且具有漂亮的复古外观。在我之前提到的视频 ( https://www.youtube.com/watch?v=gotUokTuP9U ) 中，您可以看到如何修改这样的显示屏，然后您可以使用适用于 16x2 字符 LCD 和 HD44780 驱动芯片的库。具体来说，在本例中，我们使用“LiquidCrystal”库来控制这个 VFD 显示屏。
所展示的设备构建非常简单，由几个组件组成：
- Arduino 纳米微控制器
- VFM202MDA1-1型VFD显示器略有修改
- 立体声电位器控制输入信号的强度
- 和两个电容器
用于分析和处理音频信号的库是“fix_fft”库。代码基础取自Ray Burnette，并进行了一些细微调整。新代码适用于20x2字符，提高了噪声敏感度阈值，并进行了一些细微的视觉校正。该设备内置于一个合适的盒子中，盒子由厚度为3毫米和5毫米的PVC材料制成，并贴有自粘墙纸。显示屏正面放置了一层薄而透明的滤光箔。
【Arduino 动手做】在 VFD 显示屏上 DIY Arduino 音频频谱分...
项目代码/* FFT_TEST4
Ray Burnette 20130810 function clean-up & 1284 port (328 verified)
Uses 2x16 Parallel LCD in 4-bit mode, see LiquidCrystal lib call for details
http://forum.arduino.cc/index.php?PHPSESSID=4karr49jlndufvtlqs9pdd4g96&topic=38153.15
Modified by varind in 2013: this code is public domain, enjoy!
http://www.variableindustries.com/audio-spectrum-analyzer/
328P = Binary sketch size: 5,708 bytes (of a 32,256 byte maximum)
1284P= Binary sketch size: 5,792 bytes (of a 130,048 byte maximum) Free RAM = 15456
Binary sketch size: 8,088 bytes (of a 130,048 byte maximum) (Debug)
*/
#include <Wire.h>
#include <LiquidCrystal.h>
#include <fix_fft.h>
#define DEBUG 0
#define L_IN 3 // Audio input A0 Arduino
#define R_IN 2 // Audio input A1 Arduino
const int Yres = 8;
const int gain = 3;
float peaks;
char im, data;
char Rim, Rdata;
char data_avgs;
int debugLoop;
int i;
int load;
LiquidCrystal lcd(12, 11, 5, 4, 3, 2);// RS,E,D4,D5,D6,D7
// Custom CHARACTERS
byte v1 = {
B00000, B00000, B00000, B00000, B00000, B00000, B00000, B11111
};
byte v2 = {
B00000, B00000, B00000, B00000, B00000, B00000, B11111, B11111
};
byte v3 = {
B00000, B00000, B00000, B00000, B00000, B11111, B11111, B11111
};
byte v4 = {
B00000, B00000, B00000, B00000, B11111, B11111, B11111, B11111
};
byte v5 = {
B00000, B00000, B00000, B11111, B11111, B11111, B11111, B11111
};
byte v6 = {
B00000, B00000, B11111, B11111, B11111, B11111, B11111, B11111
};
byte v7 = {
B00000, B11111, B11111, B11111, B11111, B11111, B11111, B11111
};
byte v8 = {
B11111, B11111, B11111, B11111, B11111, B11111, B11111, B11111
};
void setup() {
if (DEBUG) {
Serial.begin(9600); // hardware serial
Serial.print("Debug ON");
Serial.println("");
}
lcd.begin(16,2);
lcd.clear();
lcd.createChar(1, v1);
lcd.createChar(2, v2);
lcd.createChar(3, v3);
lcd.createChar(4, v4);
lcd.createChar(5, v5);
lcd.createChar(6, v6);
lcd.createChar(7, v7);
lcd.createChar(8, v8);
for (i=0;i<100;i++)
{
for (load = 0; load < i / 5; load++)
{
lcd.setCursor(load, 1);
lcd.write(5);
}
if (load < 1)
{
lcd.setCursor(0, 1);
lcd.write(5);
}
lcd.setCursor(load + 1, 1);
lcd.write((i - i / 5 * 5) + 1);
for (load = load + 2; load < 20; load++)
{
lcd.setCursor(load, 1);
lcd.write(9);
}
lcd.setCursor(0, 0);
lcd.print("LOADING.............");
delay(10);
}
lcd.clear();
delay(10);
}
void loop() {
for (int i = 0; i < 64; i++) { // 64 bins = 32 bins of usable spectrum data
data= ((analogRead(L_IN) / 8 ) - 256);// chose how to interpret the data from analog in
im= 0; // imaginary component
Rdata = ((analogRead(R_IN) / 8 ) - 256);// chose how to interpret the data from analog in
Rim = 0; // imaginary component
}
fix_fft(data, im, 6, 0); // Send Left channel normalized analog values through fft
fix_fft(Rdata, Rim, 6, 0); // Send Right channel normalized analog values through fft
// At this stage, we have two arrays of frequency bins deep duplicate
// calculate the absolute values of bins in the array - only want positive values
for (int i = 0; i < 40; i++) {
data = sqrt(data*data +im *im);
Rdata = sqrt(Rdata * Rdata + Rim * Rim);
// COPY the Right low-band (0-15) into the Left high-band (16-31) for display ease
if (i < 20) {
data_avgs = data;
}
else {
data_avgs = Rdata;
}
// Remap values to physical display constraints... that is, 8 display custom character indexes + "_"
data_avgs = constrain(data_avgs, 0, 9 - gain); //data samples * range (0-9) = 9
data_avgs = map(data_avgs, 0, 9 - gain, 0, Yres);// remap averaged values
}
Two16_LCD();
decay(1);
}
void Two16_LCD() {
lcd.setCursor(0, 0);
lcd.print("L"); // Channel ID replaces bin #0 due to hum & noise
lcd.setCursor(0, 1);
lcd.print("R"); // ditto
for (int x = 1; x < 20; x++) {// init 0 to show lowest band overloaded with hum
int y = x + 20; // second display line
if (data_avgs > peaks) peaks = data_avgs;
if (data_avgs > peaks) peaks = data_avgs;
lcd.setCursor(x, 0); // draw first (top) row Left
if (peaks == 0) {
lcd.print("_");// less LCD artifacts than " "
}
else {
lcd.write(peaks);
}
lcd.setCursor(x, 1); // draw second (bottom) row Right
if (peaks == 0) {
lcd.print("_");
}
else {
lcd.write(peaks);
}
}
debugLoop++;
if (DEBUG && (debugLoop > 99)) {
Serial.print( "Free RAM = " );
Serial.println( freeRam(), DEC);
Serial.println( millis(), DEC);
debugLoop = 0;
}
}
int freeRam () {
extern int __heap_start, *__brkval;
int v;
return (int) &v - (__brkval == 0 ? (int) &__heap_start : (int) __brkval);
}
void decay(int decayrate) {
int DecayTest = 1;
// reduce the values of the last peaks by 1
if (DecayTest == decayrate) {
for (int x = 0; x < 40; x++) {
peaks = peaks - 1;// subtract 1 from each column peaks
DecayTest = 0;
}
}
DecayTest++;
}
【Arduino 动手做】在 VFD 显示屏上 DIY Arduino 音频频谱分...
【Arduino 动手做】在 VFD 显示屏上 DIY Arduino 音频频谱分析仪项目链接：https://www.hackster.io/mircemk/diy-arduino-audio-spectrum-analyzer-on-vfd-display-655c10
项目作者：北马其顿 米尔塞姆克（Mirko Pavleski）
项目参考：https://www.youtube.com/watch?v=gotUokTuP9U
项目视频 ：https://www.youtube.com/watch?v=MmLOjRUFaSg
项目代码：https://www.hackster.io/code_files/594048/download
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