## Signal Generator with Arduino UNO 11 months 2 weeks ago #464

• Ray
• Posts: 244
• Karma: 8
This code stores in memory one cycle of a sinosoidal waveform (variable byte waveform[]) and then plays this cycle in a loop creating the signal.

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.

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

pedalshield_uno_signal_generator.ino:

// CC-by-www.Electrosmash.com
// Based on OpenMusicLabs and GFB previous works.
// pedalshield_uno_signal_generator.ino plays a waveform stores in memory (waveform[])
// pressing the pushbutton_1 or 2 changes the frequency.

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,
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,
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);

ADCSRB = 0x07; // t1 capture for trigger
DIDR0 = 0x01; // turn off digital inputs for adc0

// setup PWM
TCCR1A = (((PWM_QTY - 1) << 5) | 0x80 | (PWM_MODE << 1)); //
TCCR1B = ((PWM_MODE << 3) | 0x11); // ck/1
TIMSK1 = 0x20; // interrupt on capture interrupt
ICR1H = (PWM_FREQ >> 8);
ICR1L = (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 if the effect is ON.
else  digitalWrite(LED, LOW);

//nothing else here, all happens in the Timer 1 interruption.
}

ISR(TIMER1_CAPT_vect)
{

counter++; //to save resources, the pushbuttons are checked every 5000 times.
if(counter==5000)
{
counter=0;
if (speed<1024)speed=speed+1; //increase the vol
}

if (speed>0)speed=speed-1; //decrease vol
}
}

input = waveform[sample];

sample=sample+speed;
if(sample>1023)sample=0;

//write the PWM signal
OCR1AL =waveform[sample];// (((input + 0x08000)) >> 8); // convert to unsigned, send out high byte
OCR1BL = waveform[sample]; // send out low byte
}


#### File Attachment:

File Name: pedalshield_uno_signal_generator.zip
File Size: 3 KB

## Signal Generator with Arduino UNO 3 months 3 weeks ago #640

 javi OFFLINE New Member Posts: 3 Thank you received: 1 Karma: 1 hello I recently got one pedal uno. I downloaded the zip. I plugged ouput of Uno pedal into my usb/audio interface and the Tone I get is a bit distorted (not for all frequencies) is this a "normal" behavior. ? if not: do you have any comment on how to fix / understand the issue any comment on this would be appreciated regards Javier The administrator has disabled public write access. The following user(s) said Thank You: Ray

## Signal Generator with Arduino UNO 3 months 3 weeks ago #645

 Ray OFFLINE Administrator Posts: 244 Thank you received: 52 Karma: 8 Thanks for your analysis, well there is a 3rd order Sallen&Key at the output of pedalSHIELD UNO (reconstruction filter) to remove all the noise, so any guitar signal over the 5KHz mark will get some attenuation/distortion. This approach of filtering signals above 5KHz is also used by many guitar pedal manufacturers to make quieter their digital pedals and because theguitar signal does not have much content over 5K. Which freqs were you working with when you did you analysis? Thanks. The administrator has disabled public write access.

## Signal Generator with Arduino UNO 3 months 3 weeks ago #646

 javi OFFLINE New Member Posts: 3 Thank you received: 1 Karma: 1 Hello Ray In fact, it is the opposite case: Estimated from plot in my last post, sinewave is not distorted at around 2Khz and distorted at lower frequencies it can be verified "by ear" right after having flashed the signal_generator code. regards The administrator has disabled public write access.

## Signal Generator with Arduino UNO 3 months 3 weeks ago #647

 Ray OFFLINE Administrator Posts: 244 Thank you received: 52 Karma: 8 Hi, this is weird and I do not understand why is the signal distorted for you. I would check the hardware to make sure that in the output stage is all correctly connected and you do not have any cold joint or short circuit. Are you using a TL972? when you talk about frequencies, could you bee a bit more specific? The administrator has disabled public write access.
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