LED Display Displaying weird characters when triggered by ultrasonic sensor

Hello all, Im pretty new to arduino but I am trying to get the hand of it. I have a small project (soap dispenser) I am working on. The ultrasonic sensor triggers a servo that dispenses soap and the LCD at the same time. The LCD should display to “wash hands for 30 secs” and initialize a timer. The first message works fine but when it gets to the counter the LCD displays very weird characters and does not clear to display the last message of"Thank you".

My questions are:

Do you see anything wrong with my code that is not allowing for the LCD to work properly and display the timer?

Should I use lcd.clear() to clear the lcd before a new message?


LCD 1602 Module

Servo Motor (SG90)

Ultrasoni Sensor (HC-SR04)


Here is the code:

// defines pins numbers
const int servo = 9;
const int trigPin = 10;
const int echoPin = 11;
const int rs = 1, en = 2, d4 = 4, d5 = 5, d6 = 6, d7 = 7;

// defines variables
long duration;
int distance;
int StartTimer;
int Timing;
int TimeStart;
int Timer;
int TimeNow;

#include <Servo.h>
#include <LiquidCrystal.h>
LiquidCrystal lcd(rs, en, d4, d5, d6, d7);
Servo myservo;  // servo object to control a servo
int pos = 0;    // stores the servo position
char timeline[16];

void setup() {
  lcd.begin(16, 2);
  lcd.print("Stop The Spread");
  lcd.setCursor(0, 1);
  lcd.print("Wash Your Hands");
  pinMode(trigPin, OUTPUT); // Sets the trigPin as an Output
  pinMode(echoPin, INPUT); // Sets the echoPin as an Input
  myservo.attach(servo);  // attaches the servo on pin 9 to the servo object
  myservo.write(0);   // Sets Servo to initially 0 degrees
  Serial.begin(9600); // Starts the serial communication

void loop() {
  digitalWrite(trigPin, LOW);
  digitalWrite(trigPin, HIGH); // Sets the trigPin on HIGH state for 10 micro seconds
  digitalWrite(trigPin, LOW);
  duration = pulseIn(echoPin, HIGH); // Reads the echoPin, returns the sound wave travel time in microseconds
  distance = duration * 0.034 / 2; // Calculating the distance
  Serial.print("Distance: "); // Prints the distance on the Serial Monitor

  if (distance < 10) { //Check distance is less than 10cm
    myservo.write(0); // Reset the servo to 0 Degrees

    StartTimer = 1;
    Timing = 1;

    while (Timing == 1)
      if (StartTimer)
        TimeStart = millis(); // capture time at start of timer
        StartTimer = 0;
        TimeNow = millis();
        Timer = (TimeNow - TimeStart) / 1000; // diff in start time and now is time for timer
        lcd.setCursor(0, 0);
        sprintf(timeline, "%0.2d Secs", Timer);
      if (Timer > 30.0) {
        Timing = 0;


Hello all, Im pretty new to arduino but I am trying to get the hand of it.

OK then, first things first, you need to get with the program!

You need to go and read the forum instructions so that you can go back and modify your original post (not re-post it) - using the "More -> Modify" option below the right hand corner of your post - to mark up your code as such using the "</>" icon in the posting window. Just highlight each section of code (or output if you need to post that) from the IDE and click the icon.

In fact, the IDE itself has a "copy for forum" link to put these markings on a highlighted block for you so you then just paste it here in a posting window. But even before doing that, don't forget to use the "Auto-Format" (Ctrl-T) option first to make it easy to read. If you do not post it as "code" it can easily be quite garbled and is always more difficult to read due to the font.

It is inappropriate to attach it as a ".ino" file unless it is clearly too long to include in the post proper. People can usually see the mistakes directly and do not want to have to actually load it in their own IDE. And even that would also assume they are using a PC and have the IDE running on that PC.

Also tidy up your blank space. Do use blank lines, but only single blanks between complete functional blocks. Yours is practically unreadable! Looks tidy now, but didn't use the Auto-format. :roll_eyes:

And one other little detail. Do not connect the contrast potentiometer to 5 V - just leave that end unconnected (or tie it to the wiper, or if using a 10k potentiometer, tie it to the other end)!

This is a silly mistake that has become ingrained in hobby (and no doubt, some professional) designs since the "early days". Not connecting it makes contrast setting twice as easy! Using a 1k pot makes it even easier.

The problem could be that you are using pin 1 to control the LCD. That pin, and pin 0, are used for serial communication to the PC. Use another pin for the RS connection to the LCD such as pin 3 or 8.

+1 karma for putting in the code tags.