Hello everyone, I have this code here which I'm trying to fix as it's not giving the set frequency on the oscilloscope. I am new to Arduino and don't have much experience with it. This is for a project and most of this code is AI generated with a few exceptions.
Most of the code works properly as it's supposed with all the buttons and LEDs on the breadboard, it generates the waveforms (sine, saw and rectangle) but only at the wrong frequency.
For example if I put it at 1000 Hz, it generates at 180-ish Hz, I presume there's something wrong with the way it calculates the samples or something.
If anyone could help me fix it, it would be greatly appreciated.
I'm using an Arduino UNO R4 Minima for testing purposes as it has a built-in DAC on the A0 pin, but for the project I would need to use either the Uno R3 or the Nano which don't have a built in DAC.
For the Uno R3 and Nano I would need an RC filter so the PWM signal could be converted into analog signal on the output. Any guide on how to create an RC filter would also be appreciated.
#include <Wire.h>
#include <PWM.h>
#include <LiquidCrystal_I2C.h>
#include <math.h> // For the sin() function
// LCD settings (I2C address 0x27)
LiquidCrystal_I2C lcd(0x27, 16, 2);
#define MAX_FREQUENCY 20000 // Maximum frequency in Hz (20 kHz)
// DAC settings
#define DAC_PIN A0 // DAC pin on Arduino Uno R4
// Button settings
const int buttonShape = 2; // Button for changing waveform
const int buttonFreq = 3; // Button for increasing frequency
// LED settings
const int ledShape = 4; // LED for waveform change
const int ledFreq = 5; // LED for frequency change
// Variables for waveforms and frequency
volatile int currentWaveform = 0; // 0: sine, 1: sawtooth, 2: square
// Variables
int frequency = 1000; // Initial frequency
const int freqStep = 500; // Step for increasing frequency
// Other variables
int i = 0;
long sampleTime;
// Debouncing variables
unsigned long lastDebounceTimeShape = 0;
unsigned long lastDebounceTimeFreq = 0;
const unsigned long debounceDelay = 200; // Increased debounce delay in milliseconds
// Button functions (without interrupts)
void changeWaveform() {
unsigned long currentTime = millis();
if (currentTime - lastDebounceTimeShape > debounceDelay) {
currentWaveform++;
if (currentWaveform > 2) currentWaveform = 0; // Cycle through available waveforms
lastDebounceTimeShape = currentTime; // Update last press time
updateLCD(); // Update LCD
logSerial(); // Print to Serial Monitor
digitalWrite(ledShape, HIGH); // Turn on LED for waveform
}
}
void increaseFrequency() {
unsigned long currentTime = millis();
if (currentTime - lastDebounceTimeFreq > debounceDelay) {
frequency += freqStep;
if (frequency > MAX_FREQUENCY) frequency = freqStep; // Reset to minimum frequency
lastDebounceTimeFreq = currentTime; // Update last press time
updateLCD(); // Update LCD
logSerial(); // Print to Serial Monitor
digitalWrite(ledFreq, HIGH); // Turn on LED for frequency
}
}
void turnOffLEDs() {
// Turn off LEDs when buttons are released
if (digitalRead(buttonShape) == HIGH) {
digitalWrite(ledShape, LOW);
}
if (digitalRead(buttonFreq) == HIGH) {
digitalWrite(ledFreq, LOW);
}
}
// LCD update function
void updateLCD() {
lcd.clear(); // Clear the LCD before showing new text
lcd.setCursor(0, 0);
switch (currentWaveform) {
case 0: lcd.print("Sine Wave "); break; // Added space to shorten text
case 1: lcd.print("Sawtooth "); break;
case 2: lcd.print("Square "); break;
}
lcd.setCursor(0, 1);
lcd.print("Freq: ");
lcd.print(frequency);
lcd.print(" Hz "); // Added space to avoid overlapping
}
// Serial Monitor log function
void logSerial() {
Serial.print("Waveform: ");
switch (currentWaveform) {
case 0: Serial.print("Sine"); break;
case 1: Serial.print("Sawtooth"); break;
case 2: Serial.print("Square"); break;
}
Serial.print(", Frequency: ");
Serial.print(frequency);
Serial.println(" Hz");
}
void setup() {
// LCD initialization
lcd.init();
lcd.backlight();
// Pin settings
pinMode(buttonShape, INPUT_PULLUP);
pinMode(buttonFreq, INPUT_PULLUP);
pinMode(ledShape, OUTPUT); // Set LED pin as output
pinMode(ledFreq, OUTPUT); // Set LED pin as output
// Serial communication for input
Serial.begin(9600);
// Initial LCD display
updateLCD();
logSerial(); // Initial print to Serial Monitor
}
void loop() {
// Check button and LED status
if (digitalRead(buttonShape) == LOW) {
changeWaveform();
}
if (digitalRead(buttonFreq) == LOW) {
increaseFrequency();
}
// Turn off LEDs if buttons are released
turnOffLEDs();
// Calculate sample time based on current frequency
sampleTime = 1000000 / (frequency * 100); // 100 samples per cycle (100 Hz for 10kHz)
// Generate waveform
generateWaveform();
// Precise delay to achieve the desired frequency
delayMicroseconds(sampleTime); // Set delay between samples
}
void generateWaveform() {
int value = 0;
// Generate sine wave
if (currentWaveform == 0) {
value = (sin(2 * PI * i / 100) * 127 + 128); // Sine wave with offset
}
// Generate sawtooth wave
else if (currentWaveform == 1) {
value = (i % 100) * 255 / 100; // Sawtooth wave
}
// Generate square wave
else if (currentWaveform == 2) {
value = (i < 50) ? 255 : 0; // Square wave
}
// Generate waveform on DAC
analogWrite(DAC_PIN, value);
i++;
if (i == 100) i = 0; // Reset sample indices after one cycle
}
