Simple Bench Signal Generator

A simple to make AD9833-based bench signal generator, suitable for 10Hz–1Mhz - for actual practical use.

Dec 17, 2022

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audio

debugging tools

Devices & Components

Arduino Nano

Project strip board, 19x31 holes

Rotating selector

AD9833

Graphic OLED, 128 x 64

Hardware & Tools

Plier, Long Nose

Wire Stripper & Cutter, 18-10 AWG / 0.75-4mm² Capacity Wires

Soldering iron (generic)

Multitool, Screwdriver

Software & Tools

Arduino IDE

Project description

Code

arduino

Arduino code for this project

1// -----------------------------------------------------------------
2//  A simple sine-square-triangle signal generator
3// Using GY-9833 frequency generator  board, with OLED display.
4// 
5// Pushbutton sets waveform; rotary encoder  sets frequency
6// Range 10 Hz - 1 MHz
7// Michael Willems
8// Contact: michael@willems.ca
9//  Date: 16/12/2022
10// -----------------------------------------------------------------
11
12
13//  -----------------------------------------------------------------------------------------
14//  DECLARATIONS:
15// -----------------------------------------------------------------------------------------
16
17//  Include the required Arduino libraries:
18#include <Wire.h>       //for I2C
19#include  <MD_AD9833.h>  //for Frequency Generator
20#include <Encoder.h>    //for Rotary  Encoder
21
22// Pins for SPI comm with the AD9833 IC
23#define DATA  11	///<  SPI Data pin number
24#define CLK   13	///< SPI Clock pin number
25#define FSYNC  10	///< SPI Load pin number (FSYNC in AD9833 usage)
26MD_AD9833	AD(FSYNC);  //  Hardware SPI
27
28// Include the OLED stuff:
29#include <Adafruit_GFX.h>
30#include  <Adafruit_SSD1306.h>
31#define SCREEN_WIDTH 128      // OLED display width, in  pixels
32#define SCREEN_HEIGHT 64      // OLED display height, in pixels
33#define  OLED_RESET     -1     // Reset pin # (or -1 if sharing Arduino reset pin)
34//#define  SCREEN_ADDRESS 0x3C   //< See datasheet for Address; 0x3D for 128x64, 0x3C for 128x32
35#define  SCREEN_ADDRESS 0x3C   //< See datasheet for Address; 0x3D for 128x64, 0x3C for 128x32
36Adafruit_SSD1306  display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, OLED_RESET);
37
38//the rotary encoder:
39Encoder  Knob(2,3);            // The (interruptable) pins for "clock and data"
40long  KnobPosition  = 0;
41long newKnobPosition;
42
43//the rotator knob pushbutton:
44int  button2 = 6;
45long buttonTimer2 = 0;
46long buttonActive2 = false;
47long longPressTime2  = 100;
48long longPressActive2 = false;
49
50// the regular (waveform select)  button:
51int button=7;                 // for selecting waveform
52long buttonTimer  = 0;         // to see how long the button has been pressed
53boolean buttonActive  = false; // to set if the button is currently pressed
54long longPressTime = 100;     // How long to push button before we activate button mode?
55boolean longPressActive  = false;
56
57// Other declarations:
58unsigned long counter;        // for flashing  on-board LED with 1s frequency
59int activeled = 12 ;          // for heartbeat  LED, if we bother to hook it up
60byte wavetype = 1;            
61long Freq =  1000;             // starting frequency
62byte oldWavetype = 0;
63long oldFreq  = 0;
64char wavemode = 1;
65byte changepower = 0;
66long delta = 1;
67
68
69//  -----------------------------------------------------------------------------------------
70//  THE SETUP (RUNS ONCE):
71// -----------------------------------------------------------------------------------------
72//
73void  setup() {
74  pinMode(activeled, OUTPUT);
75  pinMode(button,INPUT_PULLUP);     //so  making it negative activates the button
76  pinMode(button2,INPUT_PULLUP);    //so  making it negative activates the button
77  counter = millis();
78  
79  Serial.begin(9600);
80  if(!display.begin(SSD1306_SWITCHCAPVCC, 0x3C)) {    //if display fails, stop
81    Serial.println("No display found");
82    for(;;);
83  }
84  Serial.println("Display  found OK");
85
86  AD.begin();           // start the generator board
87
88  display.display();    // show OLED logo
89  delay(1000);
90  display.clearDisplay();
91  display.display();
92  display.setTextSize(2);             // Draw 2X-scale text
93  display.setTextColor(SSD1306_WHITE);
94  display.setCursor(0,0);
95  display.println(F("SYSTEM"));
96  display.setCursor(0,20);
97  display.println(F("INITIATED"));
98  display.setCursor(0,40);
99  display.println(F("& READY"));
100  display.println();
101  display.display();
102  delay(1000);
103  display.clearDisplay();
104  displaythelabels();
105  AD.setMode(MD_AD9833::MODE_SINE);
106  AD.setFrequency(MD_AD9833::CHAN_0, Freq);
107}
108
109
110// -----------------------------------------------------------------------------------------
111//  THE LOOP:
112// -----------------------------------------------------------------------------------------
113//
114void  loop() {
115  // First, the "every half second" stuff:
116  if ((millis() - counter)  > 500) {   //was 500
117    digitalWrite (activeled,!(digitalRead(activeled)));   //the heartbeat LED
118    displayvalues(wavetype, Freq, oldWavetype, oldFreq);  //display if changes have occurred
119    counter = millis();
120  }
121
122  //  Now the "always" part of the loop:
123  
124  // Now check the WAVETYPE button:  is it pressed? If so, then change wavetype
125  if (digitalRead(button) == LOW)  {
126    if (buttonActive == false) {
127      buttonActive = true;
128      buttonTimer  = millis();  // i.e. start the timer
129    }  
130    if ((millis() - buttonTimer  > longPressTime) && (longPressActive == false)) {
131      longPressActive = true;
132      //Now change the wavetype (1-2-3-4 is sine, triangle, square, off)
133      wavetype  = wavetype+1;
134      if (wavetype>4){
135        wavetype=1;
136      }
137    }
138  } else {
139    if (buttonActive == true) {
140      if (longPressActive == true)  {
141       longPressActive = false;
142      }
143    }  
144    buttonActive =  false;
145  }
146
147  // Now check the CONTROLLER button: is it pressed? If so,  change delta effected by turning rotator knob.
148  if (digitalRead(button2) ==  LOW) {
149    if (buttonActive2 == false) {
150      buttonActive2 = true;
151      buttonTimer2  = millis();  // i.e. start the timer
152    }  
153    if ((millis() - buttonTimer2  > longPressTime2) && (longPressActive2 == false)) {
154      longPressActive2 =  true;
155      //Here, do the things you need to do to set the delta:
156      changepower  = changepower + 1;    // meaning delta is 10^changepower
157      if (changepower>5){
158        changepower=0;
159      }  
160      switch (changepower) { 
161        case  0: delta = 1; break;
162        case 1: delta = 10; break;
163        case 2: delta  = 100; break;
164        case 3: delta = 1000; break;
165        case 4: delta =  10000; break;
166        case 5: delta = 100000; break;
167      }
168      // now  display the new delta (change amount per click):
169      display.fillRect(65, 20,  35, 15, 0);
170      display.setTextSize(1);
171      display.setCursor(65,20);
172      display.println(delta);
173      display.display();
174    }
175  } else {
176    if (buttonActive2 == true) {
177      if (longPressActive2 == true) {
178       longPressActive2  = false;
179      }
180    }  
181    buttonActive2 = false;
182  }
183
184  //  read the knob position. Has it changed? Then change frequency
185  // by the delta  amount set by the controller pushbutton (1 Hz, 10 Hz, 100 Hz, etc)
186  newKnobPosition  = Knob.read()/4;
187  if (newKnobPosition != KnobPosition) { 
188    Freq = Freq  + (newKnobPosition * delta) - (KnobPosition * delta);
189    if (Freq<10) {
190      Freq=10;
191    }
192    KnobPosition = newKnobPosition;
193  }
194
195}     //  end of loop
196
197// -----------------------------------------------------------------------------------------
198//  THE FUNCTIONS:
199// -----------------------------------------------------------------------------------------
200
201void  displaythelabels() {
202  display.clearDisplay();
203  display.display();
204  display.setTextSize(1);
205  display.display();
206  // the display values stuff:  
207  display.drawRect(21,  1, 100, 14, 1);
208  display.setTextColor(SSD1306_WHITE);
209  display.setCursor(24,5);
210  display.println(F("MVW SigGen 1.0"));
211  display.setTextColor(SSD1306_WHITE);
212  // now delta and type and frequency labels:
213  display.setCursor(24,20);
214  display.println(F("Delta: 1"));
215  display.setCursor(24,35);
216  display.println(F("Type  : "));
217  display.setCursor(24,50);
218  display.println(F("Freq : "));
219  //and now activate it all!
220  display.display();
221}
222
223void displayvalues(byte  W, long F, byte OW, long OF){
224String wavestring;  
225  //show only changed type/freq:
226  if ((F != OF) || (W != OW)) {
227    display.setTextSize(1);
228    display.fillRect(65,  35, 50, 25, 0);
229    display.setCursor(65,35);
230    switch (W) {
231      case  1: wavestring = "Sine";   break;
232      case 2: wavestring = "Triangle";  break;
233      case 3: wavestring = "Square";  break;
234      case 4: wavestring = "Off";    break;
235    }
236    display.println(wavestring);
237    display.setCursor(65,50);
238    display.println(Freq);
239    display.display();
240    //Now change the chip  output waveform:
241    switch (W) {
242    case 1: wavemode = MD_AD9833::MODE_SINE;   break;
243    case 2: wavemode = MD_AD9833::MODE_TRIANGLE;  break;
244    case  3: wavemode = MD_AD9833::MODE_SQUARE1;  break;
245    case 4: wavemode = MD_AD9833::MODE_OFF;    break;
246    }
247    AD.setMode(wavemode);
248    AD.setFrequency(MD_AD9833::CHAN_0,  Freq);
249    oldWavetype = wavetype;
250    oldFreq = Freq;
251    delay(50);
252  }
253}
254
255

// -----------------------------------------------------------------
//  A simple sine-square-triangle signal generator
// Using GY-9833 frequency generator  board, with OLED display.
// 
// Pushbutton sets waveform; rotary encoder  sets frequency
// Range 10 Hz - 1 MHz
// Michael Willems
// Contact: michael@willems.ca
//  Date: 16/12/2022
// -----------------------------------------------------------------


//  -----------------------------------------------------------------------------------------
//  DECLARATIONS:
// -----------------------------------------------------------------------------------------

//  Include the required Arduino libraries:
#include <Wire.h>       //for I2C
#include  <MD_AD9833.h>  //for Frequency Generator
#include <Encoder.h>    //for Rotary  Encoder

// Pins for SPI comm with the AD9833 IC
#define DATA  11	///<  SPI Data pin number
#define CLK   13	///< SPI Clock pin number
#define FSYNC  10	///< SPI Load pin number (FSYNC in AD9833 usage)
MD_AD9833	AD(FSYNC);  //  Hardware SPI

// Include the OLED stuff:
#include <Adafruit_GFX.h>
#include  <Adafruit_SSD1306.h>
#define SCREEN_WIDTH 128      // OLED display width, in  pixels
#define SCREEN_HEIGHT 64      // OLED display height, in pixels
#define  OLED_RESET     -1     // Reset pin # (or -1 if sharing Arduino reset pin)
//#define  SCREEN_ADDRESS 0x3C   //< See datasheet for Address; 0x3D for 128x64, 0x3C for 128x32
#define  SCREEN_ADDRESS 0x3C   //< See datasheet for Address; 0x3D for 128x64, 0x3C for 128x32
Adafruit_SSD1306  display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, OLED_RESET);

//the rotary encoder:
Encoder  Knob(2,3);            // The (interruptable) pins for "clock and data"
long  KnobPosition  = 0;
long newKnobPosition;

//the rotator knob pushbutton:
int  button2 = 6;
long buttonTimer2 = 0;
long buttonActive2 = false;
long longPressTime2  = 100;
long longPressActive2 = false;

// the regular (waveform select)  button:
int button=7;                 // for selecting waveform
long buttonTimer  = 0;         // to see how long the button has been pressed
boolean buttonActive  = false; // to set if the button is currently pressed
long longPressTime = 100;     // How long to push button before we activate button mode?
boolean longPressActive  = false;

// Other declarations:
unsigned long counter;        // for flashing  on-board LED with 1s frequency
int activeled = 12 ;          // for heartbeat  LED, if we bother to hook it up
byte wavetype = 1;            
long Freq =  1000;             // starting frequency
byte oldWavetype = 0;
long oldFreq  = 0;
char wavemode = 1;
byte changepower = 0;
long delta = 1;


//  -----------------------------------------------------------------------------------------
//  THE SETUP (RUNS ONCE):
// -----------------------------------------------------------------------------------------
//
void  setup() {
  pinMode(activeled, OUTPUT);
  pinMode(button,INPUT_PULLUP);     //so  making it negative activates the button
  pinMode(button2,INPUT_PULLUP);    //so  making it negative activates the button
  counter = millis();
  
  Serial.begin(9600);
  if(!display.begin(SSD1306_SWITCHCAPVCC, 0x3C)) {    //if display fails, stop
    Serial.println("No display found");
    for(;;);
  }
  Serial.println("Display  found OK");

  AD.begin();           // start the generator board

  display.display();    // show OLED logo
  delay(1000);
  display.clearDisplay();
  display.display();
  display.setTextSize(2);             // Draw 2X-scale text
  display.setTextColor(SSD1306_WHITE);
  display.setCursor(0,0);
  display.println(F("SYSTEM"));
  display.setCursor(0,20);
  display.println(F("INITIATED"));
  display.setCursor(0,40);
  display.println(F("& READY"));
  display.println();
  display.display();
  delay(1000);
  display.clearDisplay();
  displaythelabels();
  AD.setMode(MD_AD9833::MODE_SINE);
  AD.setFrequency(MD_AD9833::CHAN_0, Freq);
}


// -----------------------------------------------------------------------------------------
//  THE LOOP:
// -----------------------------------------------------------------------------------------
//
void  loop() {
  // First, the "every half second" stuff:
  if ((millis() - counter)  > 500) {   //was 500
    digitalWrite (activeled,!(digitalRead(activeled)));   //the heartbeat LED
    displayvalues(wavetype, Freq, oldWavetype, oldFreq);  //display if changes have occurred
    counter = millis();
  }

  //  Now the "always" part of the loop:
  
  // Now check the WAVETYPE button:  is it pressed? If so, then change wavetype
  if (digitalRead(button) == LOW)  {
    if (buttonActive == false) {
      buttonActive = true;
      buttonTimer  = millis();  // i.e. start the timer
    }  
    if ((millis() - buttonTimer  > longPressTime) && (longPressActive == false)) {
      longPressActive = true;
      //Now change the wavetype (1-2-3-4 is sine, triangle, square, off)
      wavetype  = wavetype+1;
      if (wavetype>4){
        wavetype=1;
      }
    }
  } else {
    if (buttonActive == true) {
      if (longPressActive == true)  {
       longPressActive = false;
      }
    }  
    buttonActive =  false;
  }

  // Now check the CONTROLLER button: is it pressed? If so,  change delta effected by turning rotator knob.
  if (digitalRead(button2) ==  LOW) {
    if (buttonActive2 == false) {
      buttonActive2 = true;
      buttonTimer2  = millis();  // i.e. start the timer
    }  
    if ((millis() - buttonTimer2  > longPressTime2) && (longPressActive2 == false)) {
      longPressActive2 =  true;
      //Here, do the things you need to do to set the delta:
      changepower  = changepower + 1;    // meaning delta is 10^changepower
      if (changepower>5){
        changepower=0;
      }  
      switch (changepower) { 
        case  0: delta = 1; break;
        case 1: delta = 10; break;
        case 2: delta  = 100; break;
        case 3: delta = 1000; break;
        case 4: delta =  10000; break;
        case 5: delta = 100000; break;
      }
      // now  display the new delta (change amount per click):
      display.fillRect(65, 20,  35, 15, 0);
      display.setTextSize(1);
      display.setCursor(65,20);
      display.println(delta);
      display.display();
    }
  } else {
    if (buttonActive2 == true) {
      if (longPressActive2 == true) {
       longPressActive2  = false;
      }
    }  
    buttonActive2 = false;
  }

  //  read the knob position. Has it changed? Then change frequency
  // by the delta  amount set by the controller pushbutton (1 Hz, 10 Hz, 100 Hz, etc)
  newKnobPosition  = Knob.read()/4;
  if (newKnobPosition != KnobPosition) { 
    Freq = Freq  + (newKnobPosition * delta) - (KnobPosition * delta);
    if (Freq<10) {
      Freq=10;
    }
    KnobPosition = newKnobPosition;
  }

}     //  end of loop

// -----------------------------------------------------------------------------------------
//  THE FUNCTIONS:
// -----------------------------------------------------------------------------------------

void  displaythelabels() {
  display.clearDisplay();
  display.display();
  display.setTextSize(1);
  display.display();
  // the display values stuff:  
  display.drawRect(21,  1, 100, 14, 1);
  display.setTextColor(SSD1306_WHITE);
  display.setCursor(24,5);
  display.println(F("MVW SigGen 1.0"));
  display.setTextColor(SSD1306_WHITE);
  // now delta and type and frequency labels:
  display.setCursor(24,20);
  display.println(F("Delta: 1"));
  display.setCursor(24,35);
  display.println(F("Type  : "));
  display.setCursor(24,50);
  display.println(F("Freq : "));
  //and now activate it all!
  display.display();
}

void displayvalues(byte  W, long F, byte OW, long OF){
String wavestring;  
  //show only changed type/freq:
  if ((F != OF) || (W != OW)) {
    display.setTextSize(1);
    display.fillRect(65,  35, 50, 25, 0);
    display.setCursor(65,35);
    switch (W) {
      case  1: wavestring = "Sine";   break;
      case 2: wavestring = "Triangle";  break;
      case 3: wavestring = "Square";  break;
      case 4: wavestring = "Off";    break;
    }
    display.println(wavestring);
    display.setCursor(65,50);
    display.println(Freq);
    display.display();
    //Now change the chip  output waveform:
    switch (W) {
    case 1: wavemode = MD_AD9833::MODE_SINE;   break;
    case 2: wavemode = MD_AD9833::MODE_TRIANGLE;  break;
    case  3: wavemode = MD_AD9833::MODE_SQUARE1;  break;
    case 4: wavemode = MD_AD9833::MODE_OFF;    break;
    }
    AD.setMode(wavemode);
    AD.setFrequency(MD_AD9833::CHAN_0,  Freq);
    oldWavetype = wavetype;
    oldFreq = Freq;
    delay(50);
  }
}

Downloadable files

Circuit Diagram

Manual

The (pretty essential) manual

Manual

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