byte relayPin[4] = {

2,7,8,10};

//D2 -> RELAY1

//D7 -> RELAY2

//D8 -> RELAY3

//D10 -> RELAY

char input=0;

int val;

void setup() {

for(int i = 0; i < 4; i++)

pinMode(relayPin[i],OUTPUT);

Serial.begin(57600);

delay(100);

Serial.println("Press 1-4 to control the state of the relay");

Serial.println("waiting for input:");

for(int j = 0; j < 4; j++)

digitalWrite(relayPin[j],LOW);

}

void loop() {

if (Serial.available())

{

char input= Serial.read();

if(input != -1)

{

switch(input)

{

case '1':

Serial.println("Relay1");

val=digitalRead(relayPin[0]);

val=!val;

digitalWrite(relayPin[0],val);

break;