const int buttonPin1 = 2; // the number of the pushbutton pin
const int buttonPin2 = 3;
const int buttonPin3 = 4;
const int buttonPin4 = 5;
const int ledPin1 = 6; // the number of the LED pin
const int ledPin2 = 7;
const int ledPin3 = 8;
const int ledPin4 = 9;
// variables will change:
int buttonState1 = 0; // variable for reading the pushbutton status
int buttonState2 = 0;
int buttonState3 = 0;
int buttonState4 = 0;
void setup() {
// initialize the LED pin as an output:
pinMode(ledPin1, OUTPUT);
pinMode(ledPin2, OUTPUT);
pinMode(ledPin3, OUTPUT);
pinMode(ledPin4, OUTPUT);
// initialize the pushbutton pin as an input:
pinMode(buttonPin1, INPUT);
pinMode(buttonPin2, INPUT);
pinMode(buttonPin3, INPUT);
pinMode(buttonPin4, INPUT);
}
void loop(){
// read the state of the pushbutton value:
buttonState1 = digitalRead(buttonPin1);
buttonState2 = digitalRead(buttonPin2);
buttonState3 = digitalRead(buttonPin3);
buttonState4 = digitalRead(buttonPin4);
// check if the pushbutton is pressed.
// if it is, the buttonState is HIGH:
if (buttonState1 == HIGH) {
// turn LED on:
digitalWrite(ledPin1, HIGH);
digitalWrite(ledPin2, LOW);
digitalWrite(ledPin3, LOW);
digitalWrite(ledPin4, LOW);
}
else {
delay(50);
}
if (buttonState2 == HIGH) {
// turn LED on:
digitalWrite(ledPin1, LOW);
digitalWrite(ledPin2, HIGH);
digitalWrite(ledPin3, LOW);
digitalWrite(ledPin4, LOW);
}
else {
delay(50);
}
if (buttonState3 == HIGH) {
// turn LED on:
digitalWrite(ledPin1, LOW);
digitalWrite(ledPin2, LOW);
digitalWrite(ledPin3, HIGH);
digitalWrite(ledPin4, LOW);
}
else {
delay(50);
}
if (buttonState4 == HIGH) {
// turn LED on:
digitalWrite(ledPin1, LOW);
digitalWrite(ledPin2, LOW);
digitalWrite(ledPin3, LOW);
digitalWrite(ledPin4, HIGH);
}
else {
delay(50);
}
}
i has a progam like this
4 push button and 4 led
each button can switch the led
when press a button the led will stay on
while press another button and the button's led will on and other will turn off , until i press the reset and then all led's will thrn off
i have a question
how can i change my progam to make the led turn on 30 seconds and then off without using "delay"commond
because if i use delay then i can't swtich the leds because it is delaying
i aleary read the "blink without delay" but i still not sure how can it combine with my progam.
many thianks 
