Arduino lcd button input help

Question

I am working on a project and i'm trying to get the lcd to print what button was pressed, but it does not respond to the buttons I am going off of my " Arduino Projects Book " so that may be why the code is a bit messy. #include < LiquidCrystal .h> 
 LiquidCrystal lcd(12, 11, 5, 4, 3, 2); 
 const int buttonOne = 8; 
 const int buttonTwo = 7; 
 int prevSwitchState = 0; 
 int switchState = 0; 
 int prevSwitchStateTwo = 0; 
 int switchStateTwo = 0; 
 void setup (){ 
 lcd. begin (16, 2); 
 pinMode (buttonOne && buttonTwo, INPUT ); 
 lcd. print ( "Welcome" ); 
 lcd. setCursor (0,1); 
 lcd. print ( "Lftbtn = A" ); 
 delay (5000); 
 lcd. clear (); //Clears screen 
 lcd. print ( "Rgtbtn = B" ); 
 delay (5000); 
 lcd. clear (); 
 } 
 void loop (){ 
 lcd. setCursor (0,0); 
 lcd. print ( "test" ); 
 switchState = digitalRead (buttonOne); 
 if (prevSwitchState != switchState){ 
 if (buttonOne == HIGH ){ lcd. print ( "B" ); 
 } 
 } 
 else if ( prevSwitchStateTwo != switchStateTwo){ 
 if (buttonTwo == HIGH ){ 
 lcd. print ( "A" ); 
 } 
 } 
 }

mcb1 · Accepted Answer

Guys The above code will never detect the second button as its outside of the main loop, and is not being called. Try this to prove the switches work. They should be connected to +5v and the pin, with the resistor from the pin to ground. #include <LiquidCrystal.h>

LiquidCrystal lcd(12, 11, 5, 4, 3, 2);

const int buttonOne = 8;
const int buttonTwo = 7;
int prevSwitchState = 0;
int switchState = 0;
int prevSwitchStateTwo = 0;
int switchStateTwo = 0;

void setup(){

lcd.begin(16, 2);
 pinMode(buttonOne, INPUT);
 pinMode(buttonTwo, INPUT);
lcd.print("Welcome"); 
lcd.setCursor(0,1);
lcd.print("Lftbtn = A");
 delay (5000);
 lcd.clear();//Clears screen
 lcd.print("Rgtbtn = B");
 delay (5000);
 lcd.clear();

}

void loop()
{
 lcd.setCursor(0,0); //this is the top line at the far left position

//switchState = digitalRead(buttonOne);

//if (prevSwitchState != switchState){

if (digitalRead (buttonOne) == HIGH)
 { 
 lcd.print("B"); 
 } 
 if (digitalRead (buttonTwo) == HIGH)
 { 
 lcd.print("A"); 
 }

}

// this will never run as its outside the loop. I commented it to compile.

//switchStateTwo = digitalRead(buttonTwo);

// if (prevSwitchStateTwo != switchStateTwo ){

// if (buttonTwo== HIGH){

// lcd.print("A");

// }

//}

//} If you get this far then you can worry about doing the other things. Cheers Mark

Robert Peter Oakes · Answer

first you can not initialise two inputs with one statement pinMode (buttonOne && buttonTwo, INPUT ); will not work, you just tried to initialise button 0 (7 && 8) results in 0 you need to do this pinMode (buttonOne, INPUT ); pinMode (buttonTwo, INPUT ); second you cant read two buttons at one with this kind of code, you can do it but using more advanced code, your not there yet so you need switchState = digitalRead(buttonOne); 
if (prevSwitchState != switchState){ 
 if (buttonOne == HIGH){ 
 lcd.print("B"); 
 } 
} 
switchStateTwo = digitalRead(buttonTwo); 
if (prevSwitchStateTwo != switchStateTwo ){ 
 if (buttonTwo== HIGH){ 
 lcd.print("A"); 
 } 
} this should fix your problem, note this is only correcting part of your program, you will need to fit it into your code Regards Peter

Robert Peter Oakes · Answer

there is a missing bit where the previous state is not being set for each button though so even if this worked for one press it would not continue but as the previous state is initialized to a zero it should repeatedly write the value when the button is pressed and you may not notice this in reality though it is bad practice code should be more like this (Only one switch logic shown here, you need to add to the other one) switchStateTwo = digitalRead(buttonTwo); 
 if (prevSwitchStateTwo != switchStateTwo ) 
 { 
 if (buttonTwo== HIGH) 
 { 
 lcd.print("A"); 
 } 
prevSwitchStateTwo = switchStateTwo;
 }