Dear Dominik Loher:

As you see the function prototype is " void attachPop(NexTouchEventCb pop, void *ptr = NULL)"

So "&b0" is just an input paramter which is passed to the "b0PopCallback" function.

If you do not need any paramter in your user-defined callback function ,you can just pass a "NULL" to it.

I have another question :

I changed the formula to multiply the number by negative 1 :

number *= -1;

So the number goes from 1 to -1 and visa versa , I then used this value ti switch the LED

on my UNO :

if (number == 1)

{

digitalWrite(13, HIGH);

}

else

{

digitalWrite(13, LOW);

}

My question is this : How do I get it to display ON and OFF instead of 1 or -1 ?

I changed the formula to multiply the number by negative 1 :

number *= -1;

So the number goes from 1 to -1 and visa versa , I then used this value ti switch the LED

on my UNO :

if (number == 1)

{

digitalWrite(13, HIGH);

}

else

{

digitalWrite(13, LOW);

}

My question is this : How do I get it to display ON and OFF instead of 1 or -1 ?

## Dominik Loher

Hello ,

why i need the parameter "&b0" in

b0.attachPop(b0PopCallback, &b0);

it s also work without &b0.

Thanks