LCD shows output without pressing the sensor

Question

#include<LiquidCrystal.h>
LiquidCrystal lcd(13,12,11,10,9,8);
#define vibrate_sense 7
char str[70];
char *test="$GPGGA"; 
char logitude[10];
char latitude[10];
int i,j,k;
int temp;
//int Ctrl+z=26; //for sending msg
int led=13;
void setup()
{
 lcd.begin(16,2);
 Serial.begin(4800);
 pinMode(vibrate_sense, INPUT);
 pinMode(led, OUTPUT);
 lcd.setCursor(0,0);
 lcd.print("..Initializing..");
 lcd.setCursor(0,1);
 lcd.print("....System...");
delay(1000);
lcd.clear();
lcd.setCursor(0,0);
 lcd.print("Searching for");
 lcd.setCursor(0,1);
 lcd.print("Gps Signals");
 delay(2300);
lcd.clear();
 lcd.setCursor(0,0);
 lcd.print("Setup Completed");
 delay(500);
 lcd.setCursor(0,0);
 lcd.print("Accident detect");
 lcd.setCursor(0,1);
 lcd.print("& Alert system");
 delay(1500);
 lcd.clear();
 lcd.setCursor(0,0);
 lcd.print("No accident");
 lcd.setCursor(0,1);
 lcd.print("occured");
}
void loop()
{
 if (digitalRead(vibrate_sense)==0)
 {
 for(i=18;i<27;i++) //extract latitude from string
 {
 latitude[j]=str[i];
 j++;
 }
 for(i=30;i<40;i++) //extract longitude from string
 {
 logitude[k]=str[i];
 k++;
 }
lcd.clear();
 lcd.setCursor(0,0); //display latitude and longitude on 16X2 lcd display 
 lcd.print("Latitude(N)");
 lcd.print(latitude);
 lcd.setCursor(0,1);
 lcd.print("Longitude(E)");
 lcd.print(logitude);
 delay(500);
 lcd.clear();
 lcd.setCursor(0,0);
 lcd.print("Accident has");
 lcd.setCursor(0,1);
 lcd.print("been Detected");
delay(500);
lcd.clear();
 lcd.print("Sending SMS");
 delay(500);
 lcd.clear();
 Serial.begin(9600);
 Serial.println("AT+CMGF=1"); //select text mode
 delay(10);
 Serial.println("AT+CMGS=\"7066128969\""); // enter receipent number
 Serial.println("Vehicle Accident occured:");
 Serial.print("Latitude(N): "); //enter latitude in msg
 Serial.println(latitude); //enter latitude value in msg
 Serial.print("Longitude(E): "); //enter Longitude in Msg
 Serial.println(logitude); //enter longitude value in msg
 Serial.print("http://maps.google.com/maps?&z=15&mrt=yp&t=k&q=");
 Serial.println(latitude);
 Serial.println("+");
 Serial.println(logitude);
 Serial.write(26); //send msg Ctrl+z=26
 lcd.setCursor(0,0);
 lcd.print("SMS Sent");
delay(1000);
lcd.clear();
 lcd.setCursor(0,0);
 lcd.print("Help Please");
 temp=0;
 i=0;
 j=0;
 k=0;
 delay(20000); // next reading within 20 seconds
 Serial.begin(4800);
 }
}
void serialEvent()
{
 while (Serial.available()) //Serial incomming data from GPS
 {
 char inChar = (char)Serial.read();
 str[i]= inChar; //store incomming data from GPS to temparary string str[]
 i++;
 if (i < 7) 
 {
 if(str[i-1] != test[i-1]) //check for right string
 {
 i=0;
 }
 }
 if(i >=60)
 {
 break;
 }
 }
}

This is my code for my project.
It is accident detection system and it has to work like, when I press the sensor or limit switch, it has to show a message on an LCD that an accident occurred. But it shows the message on the LCD WITHOUT pressing the sensor button.

What to do? I think there is a mistake in my program. Can anybody please tell me where it is?

• jsotola: you have not learned the basics before attempting your program ...... start by writing a short program that turns on an LED when the button is pressed and turns off the LED when the button is released
• gre_gor: Do you have a pullup resistor?
• gre_gor: Please do not vandalize your or anyone else's posts. By posting on the Stack Exchange network, you've granted a non-revocable right for SE to distribute that content (under the CC BY-SA 3.0 license). By SE policy, any vandalism will be reverted.

Answer 1

First off I edited indentation in your code because incorrect indentation is little bit confusing.

#include <LiquidCrystal.h>
LiquidCrystal lcd(13,12,11,10,9,8);
#define vibrate_sense 7
char str[70];
char *test="$GPGGA"; 
char logitude[10];
char latitude[10];
int i,j,k;
int temp;
//int Ctrl+z=26; //for sending msg
int led = 13;
void setup(){
 lcd.begin(16,2);
 Serial.begin(4800);
 pinMode(vibrate_sense, INPUT);
 pinMode(led, OUTPUT);
 lcd.setCursor(0,0);
 lcd.print("..Initializing..");
 lcd.setCursor(0,1);
 lcd.print("....System...");
 delay(1000);
 lcd.clear();
 lcd.setCursor(0,0);
 lcd.print("Searching for");
 lcd.setCursor(0,1);
 lcd.print("Gps Signals");
 delay(2300);
 lcd.clear();
 lcd.setCursor(0,0);
 lcd.print("Setup Completed");
 delay(500);
 lcd.setCursor(0,0);
 lcd.print("Accident detect");
 lcd.setCursor(0,1);
 lcd.print("& Alert system");
 delay(1500);
 lcd.clear();
 lcd.setCursor(0,0);
 lcd.print("No accident");
 lcd.setCursor(0,1);
 lcd.print("occured");
}
void loop(){
 if (digitalRead(vibrate_sense) == 0){
 for(i = 18; i < 27; i ++){ //extract latitude from string
 latitude[j]=str[i];
 j++;
 }
 for(i=30;i<40;i++){ //extract longitude from string
 logitude[k] = str[i];
 k++;
 }
 lcd.clear();
 lcd.setCursor(0,0); //display latitude and longitude on 16X2 lcd display 
 lcd.print("Latitude(N)");
 lcd.print(latitude);
 lcd.setCursor(0,1);
 lcd.print("Longitude(E)");
 lcd.print(logitude);
 delay(500);
 lcd.clear();
 lcd.setCursor(0,0);
 lcd.print("Accident has");
 lcd.setCursor(0,1);
 lcd.print("been Detected");
 delay(500);
 lcd.clear();
 lcd.print("Sending SMS");
 delay(500);
 lcd.clear();
 Serial.begin(9600);
 Serial.println("AT+CMGF=1"); //select text mode
 delay(10);
 Serial.println("AT+CMGS=\"7066128969\""); // enter receipent number
 Serial.println("Vehicle Accident occured:");
 Serial.print("Latitude(N): "); //enter latitude in msg
 Serial.println(latitude); //enter latitude value in msg
 Serial.print("Longitude(E): "); //enter Longitude in Msg
 Serial.println(logitude); //enter longitude value in msg
 Serial.print("http://maps.google.com/maps?&z=15&mrt=yp&t=k&q=");
 Serial.println(latitude);
 Serial.println("+");
 Serial.println(logitude);
 Serial.write(26); //send msg Ctrl+z=26
 lcd.setCursor(0,0);
 lcd.print("SMS Sent");
 delay(1000);
 lcd.clear();
 lcd.setCursor(0,0);
 lcd.print("Help Please");
 temp = 0;
 i = 0;
 j = 0;
 k = 0;
 delay(20000); // next reading within 20 seconds
 Serial.begin(4800);
 }
}
void serialEvent(){
 while (Serial.available()){ //Serial incomming data from GPS
 char inChar = (char)Serial.read();
 str[i] = inChar; //store incomming data from GPS to temparary string str[]
 i++;
 if (i < 7){
 if(str[i-1] != test[i-1]){ //check for right string
 i = 0;
 }
 }
 if(i >= 60){
 break;
 }
 }
}

---

Second thing is this line if (digitalRead(vibrate_sense) == 0){ you are checking there vibrate_sense for value 0. Are you sure, that triggered value is 0 and not 1? Try this code to test which value is equal to triggered state.

#define vibrate_sense 7
void setup() {
 Serial.begin(9600);
 Serial.println("Sensor testing");
 pinMode(vibrate_sense, INPUT);
}
void loop() {
 Serial.println(digitalRead(vibrate_sense));
 delay(300);
}

---

Last thing is connection of your sensor/button. For button you have to use also PULL_UP/PULL_DOWN resistor to have correct logic value on digital pin.