How many cycles should I use for a specific frequency?

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Zoologist

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Hi,

I'm writing a DTMF decoding program now. And I use "DialTone_7segment" in the example as a reference. But I don't know how to calculate the "cycles" as the parameter of frequency() function. Ex:

row1.frequency(697, 21);
row2.frequency(770, 23);
row3.frequency(852, 25);
row4.frequency(941, 28);
column1.frequency(1209, 36);
column2.frequency(1336, 40);
column3.frequency(1477, 44);

Why "21" is used from 687Hz and "44" is used from 1477?:confused:

Thanks in advance.

Here is the complete example source code:

// Dial Tone (DTMF) decoding example.
//
// The audio with dial tones is connected to analog input A2,
// example for using the audio shield.
//
// This example code is in the public domain.

#include <Audio.h>
#include <Wire.h>
#include <SPI.h>
#include <SD.h>
#include <SerialFlash.h>

// Create the Audio components. These should be created in the
// order data flows, inputs/sources -> processing -> outputs
//
AudioInputAnalog audioIn;
AudioAnalyzeToneDetect row1; // 7 tone detectors are needed
AudioAnalyzeToneDetect row2; // to receive DTMF dial tones
AudioAnalyzeToneDetect row3;
AudioAnalyzeToneDetect row4;
AudioAnalyzeToneDetect column1;
AudioAnalyzeToneDetect column2;
AudioAnalyzeToneDetect column3;

// Create Audio connections between the components
//
AudioConnection patchCord1(audioIn, 0, row1, 0);
AudioConnection patchCord2(audioIn, 0, row2, 0);
AudioConnection patchCord3(audioIn, 0, row3, 0);
AudioConnection patchCord4(audioIn, 0, row4, 0);
AudioConnection patchCord5(audioIn, 0, column1, 0);
AudioConnection patchCord6(audioIn, 0, column2, 0);
AudioConnection patchCord7(audioIn, 0, column3, 0);

// pins where the 7 segment LEDs are connected
const int sevenseg_a = 17; // aaa
const int sevenseg_b = 9; // f b
const int sevenseg_c = 11; // f b
const int sevenseg_d = 12; // ggg
const int sevenseg_e = 14; // e c
const int sevenseg_f = 15; // e c
const int sevenseg_g = 10; // ddd


void setup() {
// Audio connections require memory to work. For more
// detailed information, see the MemoryAndCpuUsage example
AudioMemory(3);

//while (!Serial) ;
//delay(100);

// Configure the tone detectors with the frequency and number
// of cycles to match. These numbers were picked for match
// times of approx 30 ms. Longer times are more precise.
row1.frequency(697, 21);
row2.frequency(770, 23);
row3.frequency(852, 25);
row4.frequency(941, 28);
column1.frequency(1209, 36);
column2.frequency(1336, 40);
column3.frequency(1477, 44);

// The 7 segment display is "common anode), where the
// common pin connects to +3.3V. LOW turns the LED on
// and HIGH turns the LED off. If you use a common
// cathode display, you will need to change all the HIGH
// to LOW and LOW to HIGH.
pinMode(sevenseg_a, OUTPUT);
pinMode(sevenseg_b, OUTPUT);
pinMode(sevenseg_c, OUTPUT);
pinMode(sevenseg_d, OUTPUT);
pinMode(sevenseg_e, OUTPUT);
pinMode(sevenseg_f, OUTPUT);
pinMode(sevenseg_g, OUTPUT);
digitalWrite(sevenseg_a, HIGH);
digitalWrite(sevenseg_b, HIGH);
digitalWrite(sevenseg_c, HIGH);
digitalWrite(sevenseg_d, HIGH);
digitalWrite(sevenseg_e, HIGH);
digitalWrite(sevenseg_f, HIGH);
digitalWrite(sevenseg_g, HIGH);
}

const float row_threshold = 0.2;
const float column_threshold = 0.2;

void loop() {
float r1, r2, r3, r4, c1, c2, c3;
char digit=0;

// read all seven tone detectors
r1 = row1.read();
r2 = row2.read();
r3 = row3.read();
r4 = row4.read();
c1 = column1.read();
c2 = column2.read();
c3 = column3.read();

// print the raw data, for troubleshooting
Serial.print("tones: ");
Serial.print(r1);
Serial.print(", ");
Serial.print(r2);
Serial.print(", ");
Serial.print(r3);
Serial.print(", ");
Serial.print(r4);
Serial.print(", ");
Serial.print(c1);
Serial.print(", ");
Serial.print(c2);
Serial.print(", ");
Serial.print(c3);

// check all 12 combinations for key press
if (r1 >= row_threshold) {
if (c1 > column_threshold) {
digit = '1';
digitalWrite(sevenseg_a, HIGH);
digitalWrite(sevenseg_b, LOW);
digitalWrite(sevenseg_c, LOW);
digitalWrite(sevenseg_d, HIGH);
digitalWrite(sevenseg_e, HIGH);
digitalWrite(sevenseg_f, HIGH);
digitalWrite(sevenseg_g, HIGH);
} else if (c2 > column_threshold) {
digit = '2';
digitalWrite(sevenseg_a, LOW);
digitalWrite(sevenseg_b, LOW);
digitalWrite(sevenseg_c, HIGH);
digitalWrite(sevenseg_d, LOW);
digitalWrite(sevenseg_e, LOW);
digitalWrite(sevenseg_f, HIGH);
digitalWrite(sevenseg_g, LOW);
} else if (c3 > column_threshold) {
digit = '3';
digitalWrite(sevenseg_a, LOW);
digitalWrite(sevenseg_b, LOW);
digitalWrite(sevenseg_c, LOW);
digitalWrite(sevenseg_d, LOW);
digitalWrite(sevenseg_e, HIGH);
digitalWrite(sevenseg_f, HIGH);
digitalWrite(sevenseg_g, LOW);
}
} else if (r2 >= row_threshold) {
if (c1 > column_threshold) {
digit = '4';
digitalWrite(sevenseg_a, HIGH);
digitalWrite(sevenseg_b, LOW);
digitalWrite(sevenseg_c, LOW);
digitalWrite(sevenseg_d, HIGH);
digitalWrite(sevenseg_e, HIGH);
digitalWrite(sevenseg_f, LOW);
digitalWrite(sevenseg_g, LOW);
} else if (c2 > column_threshold) {
digit = '5';
digitalWrite(sevenseg_a, LOW);
digitalWrite(sevenseg_b, HIGH);
digitalWrite(sevenseg_c, LOW);
digitalWrite(sevenseg_d, LOW);
digitalWrite(sevenseg_e, HIGH);
digitalWrite(sevenseg_f, LOW);
digitalWrite(sevenseg_g, LOW);
} else if (c3 > column_threshold) {
digit = '6';
digitalWrite(sevenseg_a, LOW);
digitalWrite(sevenseg_b, HIGH);
digitalWrite(sevenseg_c, LOW);
digitalWrite(sevenseg_d, LOW);
digitalWrite(sevenseg_e, LOW);
digitalWrite(sevenseg_f, LOW);
digitalWrite(sevenseg_g, LOW);
}
} else if (r3 >= row_threshold) {
if (c1 > column_threshold) {
digit = '7';
digitalWrite(sevenseg_a, LOW);
digitalWrite(sevenseg_b, LOW);
digitalWrite(sevenseg_c, LOW);
digitalWrite(sevenseg_d, HIGH);
digitalWrite(sevenseg_e, HIGH);
digitalWrite(sevenseg_f, HIGH);
digitalWrite(sevenseg_g, HIGH);
} else if (c2 > column_threshold) {
digit = '8';
digitalWrite(sevenseg_a, LOW);
digitalWrite(sevenseg_b, LOW);
digitalWrite(sevenseg_c, LOW);
digitalWrite(sevenseg_d, LOW);
digitalWrite(sevenseg_e, LOW);
digitalWrite(sevenseg_f, LOW);
digitalWrite(sevenseg_g, LOW);
} else if (c3 > column_threshold) {
digit = '9';
digitalWrite(sevenseg_a, LOW);
digitalWrite(sevenseg_b, LOW);
digitalWrite(sevenseg_c, LOW);
digitalWrite(sevenseg_d, LOW);
digitalWrite(sevenseg_e, HIGH);
digitalWrite(sevenseg_f, LOW);
digitalWrite(sevenseg_g, LOW);
}
} else if (r4 >= row_threshold) {
if (c1 > column_threshold) {
digit = '*';
digitalWrite(sevenseg_a, HIGH);
digitalWrite(sevenseg_b, HIGH);
digitalWrite(sevenseg_c, HIGH);
digitalWrite(sevenseg_d, HIGH);
digitalWrite(sevenseg_e, HIGH);
digitalWrite(sevenseg_f, HIGH);
digitalWrite(sevenseg_g, LOW);
} else if (c2 > column_threshold) {
digit = '0';
digitalWrite(sevenseg_a, LOW);
digitalWrite(sevenseg_b, LOW);
digitalWrite(sevenseg_c, LOW);
digitalWrite(sevenseg_d, LOW);
digitalWrite(sevenseg_e, LOW);
digitalWrite(sevenseg_f, LOW);
digitalWrite(sevenseg_g, HIGH);
} else if (c3 > column_threshold) {
digit = '#';
digitalWrite(sevenseg_a, HIGH);
digitalWrite(sevenseg_b, LOW);
digitalWrite(sevenseg_c, LOW);
digitalWrite(sevenseg_d, HIGH);
digitalWrite(sevenseg_e, LOW);
digitalWrite(sevenseg_f, LOW);
digitalWrite(sevenseg_g, LOW);
}
}

// print the key, if any found
if (digit > 0) {
Serial.print(" --> Key: ");
Serial.print(digit);
}
Serial.println();

// uncomment these lines to see how much CPU time
// the tone detectors and audio library are using
//Serial.print("CPU=");
//Serial.print(AudioProcessorUsage());
//Serial.print("%, max=");
//Serial.print(AudioProcessorUsageMax());
//Serial.print("% ");

delay(25);
}

Z.t
 
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