Listen keyboard input and update time on LCD at the same time in Arduino

Question

I'm running into a problem on Arduino.

I want my Arduino listen to input from a piece of 12 key's keypad, this is easy, there is already keypad library avaliable.
I want to display time on a 16X2 lcd screen that I read from a RTC module, update per second. This is also easy, implemented already.

BUT, when I try to combine these two tasks, to make arduino listen keypad and keep updating the lcd, there is trouble: I'm using a delay(1000) to tell arduino loop per second, which works for updating time on lcd, but it somehow blocks the keypad listening.

Is there any solutions for this thing? Like multithreading or other clever workaround?

Instead of using delay I would recommend using interrupts. This way you will never block. Take a look at a post I wrote some time ago which shows how to do this: blog.3d-logic.com/2012/08/26/… — Pawel
Instead of using delay, how about measureing the time using millis() and run needed process after when mills() - lastRunTIme >= 1000? lastRunTime should be the last time when the process invoked and be meacured via millis() — MikeCAT

MikeCAT MikeCAT · Accepted Answer · 2015-11-09T13:33:03

How about using millis() to control the interval of LCD updating like this?

unsigned long lastRanTime;

void loop() {
  if (millis() - lastRanTime >= 1000) {
    // update the lcd
    lastRanTime = millis();
  }
  // listen for the keypad
}

Listen keyboard input and update time on LCD at the same time in Arduino

2 Answers