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TOPIC: Signal Generator with Arduino MEGA 2560/ADK

Signal Generator with Arduino MEGA 2560/ADK 1 year 8 months ago #1254

This code generates a sine wave that can be modified in frequency.
It is a great tool to troubleshoot the circuit because it only uses the output stage, so if the code works your output stage will be fine for sure.

One single cycle of a sinusoidal waveform (variable byte waveform[]) is stored in memory and played in a loop creating the sound.

You can change the frequency of the waveform by pressing the push-buttons, it simply will make the pointer go advance in 1 by 1, 2 by 2, 3 by 3, etc increasing the perceived frequency. This approach is called DDS (Direct Digital Synthesis) if you want to learn more about it there is a great tutorial on the RCArduino website: rcarduino.blogspot.co.uk/2012/12/arduino...1-sinewaves-and.html

To create the waveform samples to be stored in memory we have used this website:
www.daycounter.com/Calculators/Sine-Generator-Calculator.phtml :guitarsg:
(the desired signal is 1023 points and 255 max. amplitude)

If you want to use different waveform you can create a triangular using this website: www.daycounter.com/Calculators/Triangle-...tor-Calculator.phtml

This is the complete code of the sinewave generator for pedalshield MEGA:
// CC-by-NC www.Electrosmash.com/rights
// Based on OpenMusicLabs and GFB previous works.
// pedalshield_mega_signal_generator.ino plays a waveform stores in memory (waveform[])
// pressing the pushbutton_1 or 2 changes the frequency.
 
#include "U8glib.h"
U8GLIB_SH1106_128X64 u8g(U8G_I2C_OPT_NO_ACK);  // Display which does not send ACK
 
const byte waveform[]=
{0x80,0x80,0x81,0x82,0x83,0x83,0x84,0x85,0x86,0x87,0x87,0x88,0x89,0x8a,0x8a,0x8b,
0x8c,0x8d,0x8e,0x8e,0x8f,0x90,0x91,0x91,0x92,0x93,0x94,0x95,0x95,0x96,0x97,0x98,
0x98,0x99,0x9a,0x9b,0x9b,0x9c,0x9d,0x9e,0x9f,0x9f,0xa0,0xa1,0xa2,0xa2,0xa3,0xa4,
0xa5,0xa5,0xa6,0xa7,0xa8,0xa8,0xa9,0xaa,0xaa,0xab,0xac,0xad,0xad,0xae,0xaf,0xb0,
0xb0,0xb1,0xb2,0xb2,0xb3,0xb4,0xb5,0xb5,0xb6,0xb7,0xb7,0xb8,0xb9,0xba,0xba,0xbb,
0xbc,0xbc,0xbd,0xbe,0xbe,0xbf,0xc0,0xc0,0xc1,0xc2,0xc2,0xc3,0xc4,0xc4,0xc5,0xc6,
0xc6,0xc7,0xc8,0xc8,0xc9,0xca,0xca,0xcb,0xcc,0xcc,0xcd,0xcd,0xce,0xcf,0xcf,0xd0,
0xd0,0xd1,0xd2,0xd2,0xd3,0xd3,0xd4,0xd5,0xd5,0xd6,0xd6,0xd7,0xd7,0xd8,0xd9,0xd9,
0xda,0xda,0xdb,0xdb,0xdc,0xdc,0xdd,0xde,0xde,0xdf,0xdf,0xe0,0xe0,0xe1,0xe1,0xe2,
0xe2,0xe3,0xe3,0xe4,0xe4,0xe5,0xe5,0xe6,0xe6,0xe6,0xe7,0xe7,0xe8,0xe8,0xe9,0xe9,
0xea,0xea,0xea,0xeb,0xeb,0xec,0xec,0xed,0xed,0xed,0xee,0xee,0xef,0xef,0xef,0xf0,
0xf0,0xf0,0xf1,0xf1,0xf1,0xf2,0xf2,0xf2,0xf3,0xf3,0xf3,0xf4,0xf4,0xf4,0xf5,0xf5,
0xf5,0xf6,0xf6,0xf6,0xf7,0xf7,0xf7,0xf7,0xf8,0xf8,0xf8,0xf8,0xf9,0xf9,0xf9,0xf9,
0xfa,0xfa,0xfa,0xfa,0xfa,0xfb,0xfb,0xfb,0xfb,0xfb,0xfc,0xfc,0xfc,0xfc,0xfc,0xfc,
0xfd,0xfd,0xfd,0xfd,0xfd,0xfd,0xfd,0xfe,0xfe,0xfe,0xfe,0xfe,0xfe,0xfe,0xfe,0xfe,
0xfe,0xfe,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,
0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xfe,
0xfe,0xfe,0xfe,0xfe,0xfe,0xfe,0xfe,0xfe,0xfe,0xfd,0xfd,0xfd,0xfd,0xfd,0xfd,0xfd,
0xfd,0xfc,0xfc,0xfc,0xfc,0xfc,0xfb,0xfb,0xfb,0xfb,0xfb,0xfb,0xfa,0xfa,0xfa,0xfa,
0xf9,0xf9,0xf9,0xf9,0xf8,0xf8,0xf8,0xf8,0xf7,0xf7,0xf7,0xf7,0xf6,0xf6,0xf6,0xf5,
0xf5,0xf5,0xf5,0xf4,0xf4,0xf4,0xf3,0xf3,0xf3,0xf2,0xf2,0xf2,0xf1,0xf1,0xf1,0xf0,
0xf0,0xef,0xef,0xef,0xee,0xee,0xee,0xed,0xed,0xec,0xec,0xeb,0xeb,0xeb,0xea,0xea,
0xe9,0xe9,0xe8,0xe8,0xe8,0xe7,0xe7,0xe6,0xe6,0xe5,0xe5,0xe4,0xe4,0xe3,0xe3,0xe2,
0xe2,0xe1,0xe1,0xe0,0xe0,0xdf,0xdf,0xde,0xde,0xdd,0xdd,0xdc,0xdc,0xdb,0xdb,0xda,
0xd9,0xd9,0xd8,0xd8,0xd7,0xd7,0xd6,0xd5,0xd5,0xd4,0xd4,0xd3,0xd3,0xd2,0xd1,0xd1,
0xd0,0xd0,0xcf,0xce,0xce,0xcd,0xcc,0xcc,0xcb,0xcb,0xca,0xc9,0xc9,0xc8,0xc7,0xc7,
0xc6,0xc5,0xc5,0xc4,0xc3,0xc3,0xc2,0xc1,0xc1,0xc0,0xbf,0xbf,0xbe,0xbd,0xbd,0xbc,
0xbb,0xbb,0xba,0xb9,0xb9,0xb8,0xb7,0xb6,0xb6,0xb5,0xb4,0xb4,0xb3,0xb2,0xb1,0xb1,
0xb0,0xaf,0xaf,0xae,0xad,0xac,0xac,0xab,0xaa,0xa9,0xa9,0xa8,0xa7,0xa6,0xa6,0xa5,
0xa4,0xa3,0xa3,0xa2,0xa1,0xa0,0xa0,0x9f,0x9e,0x9d,0x9d,0x9c,0x9b,0x9a,0x9a,0x99,
0x98,0x97,0x96,0x96,0x95,0x94,0x93,0x93,0x92,0x91,0x90,0x90,0x8f,0x8e,0x8d,0x8c,
0x8c,0x8b,0x8a,0x89,0x88,0x88,0x87,0x86,0x85,0x85,0x84,0x83,0x82,0x81,0x81,0x80,
0x7f,0x7e,0x7e,0x7d,0x7c,0x7b,0x7a,0x7a,0x79,0x78,0x77,0x77,0x76,0x75,0x74,0x73,
0x73,0x72,0x71,0x70,0x6f,0x6f,0x6e,0x6d,0x6c,0x6c,0x6b,0x6a,0x69,0x69,0x68,0x67,
0x66,0x65,0x65,0x64,0x63,0x62,0x62,0x61,0x60,0x5f,0x5f,0x5e,0x5d,0x5c,0x5c,0x5b,
0x5a,0x59,0x59,0x58,0x57,0x56,0x56,0x55,0x54,0x53,0x53,0x52,0x51,0x50,0x50,0x4f,
0x4e,0x4e,0x4d,0x4c,0x4b,0x4b,0x4a,0x49,0x49,0x48,0x47,0x46,0x46,0x45,0x44,0x44,
0x43,0x42,0x42,0x41,0x40,0x40,0x3f,0x3e,0x3e,0x3d,0x3c,0x3c,0x3b,0x3a,0x3a,0x39,
0x38,0x38,0x37,0x36,0x36,0x35,0x34,0x34,0x33,0x33,0x32,0x31,0x31,0x30,0x2f,0x2f,
0x2e,0x2e,0x2d,0x2c,0x2c,0x2b,0x2b,0x2a,0x2a,0x29,0x28,0x28,0x27,0x27,0x26,0x26,
0x25,0x24,0x24,0x23,0x23,0x22,0x22,0x21,0x21,0x20,0x20,0x1f,0x1f,0x1e,0x1e,0x1d,
0x1d,0x1c,0x1c,0x1b,0x1b,0x1a,0x1a,0x19,0x19,0x18,0x18,0x17,0x17,0x17,0x16,0x16,
0x15,0x15,0x14,0x14,0x14,0x13,0x13,0x12,0x12,0x11,0x11,0x11,0x10,0x10,0x10,0xf,
0xf,0xe,0xe,0xe,0xd,0xd,0xd,0xc,0xc,0xc,0xb,0xb,0xb,0xa,0xa,0xa,
0xa,0x9,0x9,0x9,0x8,0x8,0x8,0x8,0x7,0x7,0x7,0x7,0x6,0x6,0x6,0x6,
0x5,0x5,0x5,0x5,0x4,0x4,0x4,0x4,0x4,0x4,0x3,0x3,0x3,0x3,0x3,0x2,
0x2,0x2,0x2,0x2,0x2,0x2,0x2,0x1,0x1,0x1,0x1,0x1,0x1,0x1,0x1,0x1,
0x1,0x0,0x0,0x0,0x0,0x0,0x0,0x0,0x0,0x0,0x0,0x0,0x0,0x0,0x0,0x0,
0x0,0x0,0x0,0x0,0x0,0x0,0x0,0x0,0x0,0x0,0x0,0x0,0x0,0x0,0x1,0x1,
0x1,0x1,0x1,0x1,0x1,0x1,0x1,0x1,0x1,0x2,0x2,0x2,0x2,0x2,0x2,0x2,
0x3,0x3,0x3,0x3,0x3,0x3,0x4,0x4,0x4,0x4,0x4,0x5,0x5,0x5,0x5,0x5,
0x6,0x6,0x6,0x6,0x7,0x7,0x7,0x7,0x8,0x8,0x8,0x8,0x9,0x9,0x9,0xa,
0xa,0xa,0xb,0xb,0xb,0xc,0xc,0xc,0xd,0xd,0xd,0xe,0xe,0xe,0xf,0xf,
0xf,0x10,0x10,0x10,0x11,0x11,0x12,0x12,0x12,0x13,0x13,0x14,0x14,0x15,0x15,0x15,
0x16,0x16,0x17,0x17,0x18,0x18,0x19,0x19,0x19,0x1a,0x1a,0x1b,0x1b,0x1c,0x1c,0x1d,
0x1d,0x1e,0x1e,0x1f,0x1f,0x20,0x20,0x21,0x21,0x22,0x23,0x23,0x24,0x24,0x25,0x25,
0x26,0x26,0x27,0x28,0x28,0x29,0x29,0x2a,0x2a,0x2b,0x2c,0x2c,0x2d,0x2d,0x2e,0x2f,
0x2f,0x30,0x30,0x31,0x32,0x32,0x33,0x33,0x34,0x35,0x35,0x36,0x37,0x37,0x38,0x39,
0x39,0x3a,0x3b,0x3b,0x3c,0x3d,0x3d,0x3e,0x3f,0x3f,0x40,0x41,0x41,0x42,0x43,0x43,
0x44,0x45,0x45,0x46,0x47,0x48,0x48,0x49,0x4a,0x4a,0x4b,0x4c,0x4d,0x4d,0x4e,0x4f,
0x4f,0x50,0x51,0x52,0x52,0x53,0x54,0x55,0x55,0x56,0x57,0x57,0x58,0x59,0x5a,0x5a,
0x5b,0x5c,0x5d,0x5d,0x5e,0x5f,0x60,0x60,0x61,0x62,0x63,0x64,0x64,0x65,0x66,0x67,
0x67,0x68,0x69,0x6a,0x6a,0x6b,0x6c,0x6d,0x6e,0x6e,0x6f,0x70,0x71,0x71,0x72,0x73,
0x74,0x75,0x75,0x76,0x77,0x78,0x78,0x79,0x7a,0x7b,0x7c,0x7c,0x7d,0x7e,0x7f,0x80,
};
 
//defining harware resources.
#define LED 13
#define FOOTSWITCH 12
#define TOGGLE 2
#define PUSHBUTTON_1 A5
#define PUSHBUTTON_2 A4

//defining the output PWM parameters
#define PWM_FREQ 0x00FF // pwm frequency - 31.3KHz
#define PWM_MODE 0 // Fast (1) or Phase Correct (0)
#define PWM_QTY 2 // 2 PWMs in parallel

//other variables
int input,inputa,inputb, speed=1;
int counter=0;
int sample=0;
 
void setup() {
  //setup IO
  pinMode(FOOTSWITCH, INPUT_PULLUP);
  pinMode(TOGGLE, INPUT_PULLUP);
  pinMode(PUSHBUTTON_1, INPUT_PULLUP);
  pinMode(PUSHBUTTON_2, INPUT_PULLUP);
  pinMode(LED, OUTPUT);
  pinMode(6, OUTPUT); //PWM0 as output
  pinMode(7, OUTPUT); //PWM1 as output
 
  // setup ADC
  ADMUX = 0x60; // left adjust, adc0, internal vcc
  ADCSRA = 0xe5; // turn on adc, ck/32, auto trigger
  ADCSRB = 0x07; // t1 capture for trigger
  DIDR0 = 0x01; // turn off digital inputs for adc0
 
  // setup PWM
  TCCR4A = (((PWM_QTY - 1) << 5) | 0x80 | (PWM_MODE << 1)); //
  TCCR4B = ((PWM_MODE << 3) | 0x11); // ck/1
  TIMSK4 = 0x20; // interrupt on capture interrupt
  ICR4H = (PWM_FREQ >> 8);
  ICR4L = (PWM_FREQ & 0xff);
  DDRB |= ((PWM_QTY << 1) | 0x02); // turn on outputs
  sei(); // turn on interrupts - not really necessary with arduino
  }
 
void loop() 
{
  //Turn on the LED and write the OLED if the effect is ON.
  if (digitalRead(FOOTSWITCH)) 
  {
  digitalWrite(LED, HIGH); //light the LED
    u8g.firstPage(); 
 do {
   u8g.setFont(u8g_font_helvR14r);
   u8g.drawStr( 0, 16, "    SIGNAL  ");    
   u8g.drawStr( 0, 36, " GENERATOR ");  
   u8g.setPrintPos(50, 64); 
   u8g.setFont(u8g_font_helvR24r); 
   u8g.print(speed);
  } while( u8g.nextPage() );
  }
    else  
  {  
    digitalWrite(LED, LOW); // switch-off the LED
    u8g.firstPage(); 
    do {
        u8g.setFont(u8g_font_helvR24r);
        u8g.drawStr( 0, 30, "EFFECT");    
        u8g.drawStr( 0, 60, "   OFF");   
        } while( u8g.nextPage() );
  }
}
 
ISR(TIMER4_CAPT_vect) 
{
 
counter++; //to save resources, the pushbuttons are checked every 1000 times.
if(counter==1000)
{ 
counter=0;
if (!digitalRead(PUSHBUTTON_2)) {
  if (speed<1024)speed=speed+1; //increase the vol
    digitalWrite(LED, LOW); //blinks the led
    }
 
    if (!digitalRead(PUSHBUTTON_1)) {
  if (speed>0)speed=speed-1; //decrease vol
  digitalWrite(LED, LOW); //blinks the led
    }
}
 
  sample=sample+speed;
  if(sample>1023)sample=0;
 
  //write the PWM output signal
 OCR4AL =waveform[sample];
 OCR4BL = waveform[sample];
}
 
 
 
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