How to turn 4x4 keypad into one wire analog signal and how to make this design robust?

[@KangJangkrik]

Well... That's more complicated than I thought :/

[@franciscocasas2082]

Have you ever thought to develop a library for arduino with your code?, it's better that another existing libraries, because it don't trow fake keys, Congrats again.

[@franciscocasas2082]

Congrats, good design, if I can try with a STM32 wich is 3.3v analog in, I'll need to do any modifications? or just with the built in analog reference is sufficient?

[@InsaneInvader]

You can use any MCU running at any voltage. Just use the same voltage Vin for the keyboard and for the ADC's Vref (literaly the same, Vin connected to Vref) - it makes the reference voltage accuracy not important at all.

[@franciscocasas2082]

it's me again, with a doubt. I need to implement long press functions do you have any code to implement some like that?
Regards

[@InsaneInvader]

Hi! Unfortunately no code for that but I think it is something like that:
while(1) // system main loop
{
delay(1); // wait 1ms
if(key_state != key_state_old) // detect the change
{
if(key_state == 1) // detect the key is pressed
{
timeout = 100; // start the timeout counting
}
else // the key is released
{
timeout = 0; // stop time counting
}
}
key_state_old = key_state; // remember it for future usage
if(timeout) // timeout counting in progress
{
timeout--; // time goes down
if(time == 0) // finished
{
on_key_held_down(); // the key was constantly pressed for 100 * 1ms
}
}
}
However it looks like a code for debouncing... Hope you come out with your own solution!