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sâmbătă, 28 martie 2015

Generator de semnal cu AD9850 si Arduino

   Un generator de semnal este util pentru a testa diverse montaje, fie audio, fie de radiofrecventa, asa ca m-am hotarat, cu greu, ce-i adevarat, sa imi fac si eu un asemenea generator de semnal cu afisarea frecventei pe un ecran alfanumeric lcd cu 16 coloane si 2 randuri, iar frecventa se schimba cu ajutorului unui encoder.
   Proiectul, care este baza experimentului, se gaseste la adresa http://www.ad7c.com/projects/ad9850-dds-vfo/ si foloseste memorarea frecventei in EEPROM (la repornire vom avea frecventa memorata):
   Schema de baza este cea din articol, la care am scos butonul de frecventa intermediara.. a mea ramanand asa:
   Dupa incarcarea sketch-ului de pe site-ul mentionat mai sus, am obtinut pe una din iesirile de semnal dreptunghiular:
 
 
 
 
 
 
 
iar pe una de semnal sinusoidal (dupa ce am umblat la semireglabilul de pe modul, ca nu aparea sinusoida... deci e pun la casa omului un osciloscop):
 
 
 
 
   Pentru a verifica frecventa generata, am folosit o alta placa Arduino cu sketch de frecventmetru (cum este prezentat in articolul de la http://interface.khm.de/index.php/lab/interfaces-advanced/arduino-frequency-counter-library/ si l-am prezentat si eu in articolul Frecventmetru cu.. Arduino:
)
 
 
   Sketch-ul folosit de mine, cu foarte mici modificari fata de cel original este:
/*
Main code by Richard Visokey AD7C - http://www.ad7c.com
Revision 2.0 - November 6th, 2013
adapted sketch 1.2 - january 1st, 2015 - by Nicu Florica - http://www.tehnic.go.ro
http://nicuflorica.blogspot.ro/
http://arduinotehniq.blogsopt.com/
*/

// Include the library code
#include <LiquidCrystal.h>
#include <rotary.h>
#include <EEPROM.h>

//Setup some items
#define W_CLK 8   // Pin 8 - connect to AD9850 module word load clock pin (CLK)
#define FQ_UD 9   // Pin 9 - connect to freq update pin (FQ)
#define DATA 10   // Pin 10 - connect to serial data load pin (DATA)
#define RESET 11  // Pin 11 - connect to reset pin (RST) 
#define pulseHigh(pin) {digitalWrite(pin, HIGH); digitalWrite(pin, LOW); }
Rotary r = Rotary(2,3); // sets the pins the rotary encoder uses.  Must be interrupt pins.
LiquidCrystal lcd(13, 12, 7, 6, 5, 4); // I used an odd pin combination because I need pin 2 and 3 for the interrupts.
int_fast32_t rx=7200000; // Starting frequency of VFO
int_fast32_t rx2=1; // variable to hold the updated frequency
int_fast32_t increment = 1; // starting VFO update increment in HZ.
int buttonstate = 0;
String hertz = "1 Hz";
int  hertzPosition = 6;
byte ones,tens,hundreds,thousands,tenthousands,hundredthousands,millions ;  //Placeholders
String freq; // string to hold the frequency
int_fast32_t timepassed = millis(); // int to hold the arduino miilis since startup
int memstatus = 1;  // value to notify if memory is current or old. 0=old, 1=current.

int ForceFreq = 0;  // Change this to 0 after you upload and run a working sketch to activate the EEPROM memory.  YOU MUST PUT THIS BACK TO 0 AND UPLOAD THE SKETCH AGAIN AFTER STARTING FREQUENCY IS SET!

void setup() {
  pinMode(A0,INPUT); // Connect to a button that goes to GND on push
  digitalWrite(A0,HIGH);
  lcd.begin(16, 2);
  PCICR |= (1 << PCIE2);
  PCMSK2 |= (1 << PCINT18) | (1 << PCINT19);
  sei();
  pinMode(FQ_UD, OUTPUT);
  pinMode(W_CLK, OUTPUT);
  pinMode(DATA, OUTPUT);
  pinMode(RESET, OUTPUT); 
  pulseHigh(RESET);
  pulseHigh(W_CLK);
  pulseHigh(FQ_UD);  // this pulse enables serial mode on the AD9850 - Datasheet page 12.
  lcd.setCursor(hertzPosition,1);    
  lcd.print(hertz);
   // Load the stored frequency  
  if (ForceFreq == 0) {
    freq = String(EEPROM.read(0))+String(EEPROM.read(1))+String(EEPROM.read(2))+String(EEPROM.read(3))+String(EEPROM.read(4))+String(EEPROM.read(5))+String(EEPROM.read(6));
    rx = freq.toInt();  
  }
}


void loop() {
  if (rx != rx2){    
        showFreq();
        sendFrequency(rx);
        rx2 = rx;
      }
      
  buttonstate = digitalRead(A0);
  if(buttonstate == LOW) {
        setincrement();        
    };

  // Write the frequency to memory if not stored and 2 seconds have passed since the last frequency change.
    if(memstatus == 0){   
      if(timepassed+2000 < millis()){
        storeMEM();
        }
      }   
}


ISR(PCINT2_vect) {
  unsigned char result = r.process();
  if (result) {    
    if (result == DIR_CW){rx=rx+increment;}
    else {rx=rx-increment;};       
      if (rx >=30000000){rx=rx2;}; // UPPER VFO LIMIT
      if (rx <=1){rx=rx2;}; // LOWER VFO LIMIT
  }
}



// frequency calc from datasheet page 8 = <sys clock> * <frequency tuning word>/2^32
void sendFrequency(double frequency) {  
  int32_t freq = frequency * 4294967295/125000000;  // note 125 MHz clock on 9850.  You can make 'slight' tuning variations here by adjusting the clock frequency.
  for (int b=0; b<4; b++, freq>>=8) {
    tfr_byte(freq & 0xFF);
  }
  tfr_byte(0x000);   // Final control byte, all 0 for 9850 chip
  pulseHigh(FQ_UD);  // Done!  Should see output
}
// transfers a byte, a bit at a time, LSB first to the 9850 via serial DATA line
void tfr_byte(byte data)
{
  for (int i=0; i<8; i++, data>>=1) {
    digitalWrite(DATA, data & 0x01);
    pulseHigh(W_CLK);   //after each bit sent, CLK is pulsed high
  }
}

void setincrement(){
  if(increment == 1){increment = 10; hertz = "10 Hz"; hertzPosition=5;}
  else if(increment == 10){increment = 50; hertz = "50 Hz"; hertzPosition=5;}
  else if (increment == 50){increment = 100;  hertz = "100 Hz"; hertzPosition=4;}
  else if (increment == 100){increment = 500; hertz="500 Hz"; hertzPosition=4;}
  else if (increment == 500){increment = 1000; hertz="1 kHz"; hertzPosition=6;}
  else if (increment == 1000){increment = 2500; hertz="2.5 kHz"; hertzPosition=4;}
  else if (increment == 2500){increment = 5000; hertz="5 kHz"; hertzPosition=6;}
  else if (increment == 5000){increment = 10000; hertz="10 kHz"; hertzPosition=5;}
  else if (increment == 10000){increment = 100000; hertz="100 kHz"; hertzPosition=4;}
  else if (increment == 100000){increment = 1000000; hertz="1 MHz"; hertzPosition=6;}  
  else{increment = 1; hertz = "1 Hz"; hertzPosition=6;};  
   lcd.setCursor(0,1);
   lcd.print("                ");
   lcd.setCursor(hertzPosition,1); 
   lcd.print(hertz); 
   delay(250); // Adjust this delay to speed up/slow down the button menu scroll speed.
};

void showFreq(){
    millions = int(rx/1000000);
    hundredthousands = ((rx/100000)%10);
    tenthousands = ((rx/10000)%10);
    thousands = ((rx/1000)%10);
    hundreds = ((rx/100)%10);
    tens = ((rx/10)%10);
    ones = ((rx/1)%10);
    lcd.setCursor(0,0);
    lcd.print("                ");
   if (millions > 9)
   {
       lcd.setCursor(1,0);
      }
   else 
   {
        lcd.setCursor(2,0); 
   }
    lcd.print(millions);
    lcd.print(",");
    lcd.print(hundredthousands);
    lcd.print(tenthousands);
    lcd.print(thousands);
    lcd.print(".");
    lcd.print(hundreds);
    lcd.print(tens);
    lcd.print(ones);
    lcd.print(" MHz  ");
    timepassed = millis();
    memstatus = 0; // Trigger memory write
};

void storeMEM(){
  //Write each frequency section to a EPROM slot.  Yes, it's cheating but it works!
   EEPROM.write(0,millions);
   EEPROM.write(1,hundredthousands);
   EEPROM.write(2,tenthousands);
   EEPROM.write(3,thousands);
   EEPROM.write(4,hundreds);       
   EEPROM.write(5,tens);
   EEPROM.write(6,ones);   
   memstatus = 1;  // Let program know memory has been written
   lcd.setCursor(1,15);
   lcd.print("*");
   delay(500);
   lcd.setCursor(1,15);
   lcd.print(" ");
 
};
   Am facut is niste filmulete, care prezinta mai bine modul de functionare:
generator de semnal cu AD9850 si reglaj cu encoder rotativ
generator de semnal cu AD9850 si reglaj cu encoder rotativ (2)
generator de semnal cu AD9850 si reglaj cu encoder rotativ (3)
Arduino AD9850 DDS + Arduino frequencymeter
   Avand un afisaj cu touch, vreau sa fac un generator cu AD9850 la care sa introduc frecventa prin atingere, dupa cum e prezentat in filmuletul preliminar numit adaptor pentru afisaj TFT cu senzor tactil si generator semnal cu AD9850 (2)

Un comentariu:

  1. Buna ziua.
    Am reusit sa realizez montajul original din http://f5mna.free.fr/ , cu urmatoarele deosebiri:
    1. Am folosit AD9851 (foloseste un cuart de 30 MHz cu multiplicare de 6 ori, deci 180 MHz)
    2. Schema este putin gresita, in loc de pinul 13 trebuie introdus pinul 12, pentru a se corela cu sketch-ul folosit.
    3. Am modificat partea cu butoanele de selectie, deoarece sketch-ul original nu merge. Am folosit sketch-ul de la afisaj pe care l-am introdus ad-literam.
    In rest e bine ... functioneaza.

    RăspundețiȘtergere