LCD I2C not resetting together with the Arduino UNO, is there a solution?

Projects General Guidance
1 
#include <Wire.h>
#include <LiquidCrystal_I2C.h>

// Constants
//required variables
int prev = 0, stepCount = 0;
unsigned long previousMillis = 0;
const long interval = 1000;  
unsigned long currentMillis;

float v, vout, vin;  //variabls for calculating voltage

// Initialize the LCD, set the LCD address to 0x27 for a 16 chars and 2 line display
LiquidCrystal_I2C lcd(0x27, 16, 2);

void setup() {
  // Initialize serial communication
  Serial.begin(9600);
  pinMode(8,OUTPUT);//led indication
  // Initialize the LCD
  lcd.init();
  lcd.backlight();

  // Print a message to the LCD
  lcd.print("FOOT STEP POWER");
  lcd.setCursor(0, 1);
  lcd.print("   GENERATOR");
  delay(2000);
  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print("STEP COUNT:");
  lcd.setCursor(0, 1);
  lcd.print("VOLTAGE:");
}

void loop() {

  v = analogRead(A0);
  currentMillis = millis();  //calculating time

  if (v != 0 and (prev == 0)) {
    stepCount += 1;         // calculating steps
    digitalWrite(8, HIGH);  //led indication
    lcd.setCursor(12, 0);
    lcd.print(stepCount);
  } else {
    if (currentMillis - previousMillis >= 100) {
      previousMillis = currentMillis;  //time in milliseconds
      digitalWrite(8, LOW);
    }
  }
  prev = v;
  lcd.setCursor(9, 1);
  //calculation of voltage
  vout = (v * 5.00) / 1024.00;
  vin = (vout / 0.040909)*100;

  lcd.print(vin);
  lcd.print("mV ");
  delay(200);
}

that's the code I'm using and;
"LiquidCrystal I2C (by Frank de Brabander) is the intalled library

2

What, exactly, is the LCD not doing that you want it to do when you reset the Uno? Please be specific and detailed.

3

usually, when I'm resetting the Arduino UNO the LCD I2C is also resetting or having a short blackout.. and will process the code. but the problem is, it's not happening.

4

I can't say that I've ever noticed that an LCD, either hooked up parallel or I2C, has reset in unison with the Uno being reset. So I don't have any idea what it is you think you've observed.

5

Executing lcd.init() and allowing it to complete is mandatory before redrawing on the display is mandatory before redrawing after power is reapplied to the lcd.

If you power them on at the same time, maybe the arduino sends the init commands before the display is ready.

6

The hd44780 chipset does not have a hardware reset.
The initialization process for a hd44780 LCD includes a command sequence that the host first sends to the LCD to get the LCD back into a known state where the host can communicate (send instructions) to the LCD.
After that, the initialization process sets the LCD to the appropriate mode.
There is no reset of the LCD involved as there is no way to h/w reset the LCD.
The only thing that does an actual "reset" is a power cycle as the LCD does some internal initialization on power up. This is what creates the black boxes on the display after power up.

What can happen is depending on the LCD and how the backlight circuitry works, the library may do something in the initialization code that could cause the backlight to turn off or flicker.
Or if the library has a long delay or is slow, the LCD may show blocks on power up before the library takes control and re-initializes and clears the display.
But these dark blocks will not show up when the host (arduino) is reset since resetting the host does not power cycle the LCD.

@hannahaustria
can you provide more details about what you are seeing / experiencing and/or explain what you think is happening or not happening.

--- bill

7

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