It has low battery cut off voltage at 10.5V to protect the battery from over discharge.
The output is square waveform and the maximum output power depends on the power of your transformer and also the MOSFETs and heatsink's size.
If you want to use Arduino UNO instead of Arduino MEGA, you have to connect the pin A4 of the Arduino UNO to SDA of the LCD and pin A5 of the Arduino UNO to SCL of the LCD, Rest of the wiring and even the code remains the same!
#include <Wire.h>
#include <LiquidCrystal_I2C.h>
#include <avr/io.h>
#include <avr/interrupt.h>
LiquidCrystal_I2C lcd(0x27, 16, 2); // Try 0x3F if 0x27 doesn’t work
const int square1 = 8;
const int square2 = 9;
const int buttonPin = 2;
volatile bool waveState = false; // Toggles HIGH/LOW
volatile bool outputEnabled = false; // ON/OFF by user
bool voltageOK = true; // Low voltage check
const unsigned int deadTimeMicros = 200;
const float voltageThreshold = 10.5; // Cutoff threshold
unsigned long lastLCDUpdate = 0;
const unsigned long lcdInterval = 200;
unsigned long lastButtonTime = 0;
const unsigned long debounceDelay = 200;
void setup() {
pinMode(square1, OUTPUT);
pinMode(square2, OUTPUT);
pinMode(buttonPin, INPUT_PULLUP);
digitalWrite(square1, LOW);
digitalWrite(square2, LOW);
lcd.init();
lcd.backlight();
lcd.clear();
attachInterrupt(digitalPinToInterrupt(buttonPin), toggleOutput, FALLING);
// Timer1 for 50Hz waveform (10ms toggle = 20ms full cycle)
noInterrupts();
TCCR1A = 0;
TCCR1B = 0;
TCNT1 = 0;
OCR1A = 2499; // 10ms at 16MHz / 64
TCCR1B |= (1 << WGM12);
TCCR1B |= (1 << CS11) | (1 << CS10);
TIMSK1 |= (1 << OCIE1A);
interrupts();
}
ISR(TIMER1_COMPA_vect) {
if (outputEnabled && voltageOK) {
waveState = !waveState;
if (waveState) {
digitalWrite(square2, LOW);
delayMicroseconds(deadTimeMicros);
digitalWrite(square1, HIGH);
} else {
digitalWrite(square1, LOW);
delayMicroseconds(deadTimeMicros);
digitalWrite(square2, HIGH);
}
} else {
digitalWrite(square1, LOW);
digitalWrite(square2, LOW);
}
}
void loop() {
// Update LCD every 200ms
if (millis() - lastLCDUpdate >= lcdInterval) {
lastLCDUpdate = millis();
int adc0 = analogRead(A0); delay(2);
float v0 = adc0 * (5.0 / 1023.0)*10;
// Voltage check
voltageOK = (v0 >= voltageThreshold);
// Display voltages
lcd.setCursor(0, 0);
lcd.print("BATTERY: ");
lcd.print(v0, 2);
lcd.print(" V ");
// Show status
lcd.setCursor(1, 1);
if (!voltageOK) {
lcd.print("BATTERY IS LOW");
} else {
lcd.print(outputEnabled ? "INVERTER IS ON " : "INVERTER IS OFF");
}
}
}
void toggleOutput() {
unsigned long now = millis();
if (now - lastButtonTime > debounceDelay) {
outputEnabled = !outputEnabled;
lastButtonTime = now;
}
}
