Fun_with_millis

The Arduino millis() function can be used in almost every situation. These are small demonstration sketches to show how to use millis() in different situations.
I hope you like them and have fun with the sketches 😄

These sketches can be simulated with Wokwi.

• millis_basic_demo.ino
  
  This is the basic example. It uses the serial monitor and no extra hardware is required. Three different software timers with millis are used to send something to the serial monitor.

• millis_different_on_and_off_times.ino
  
  An example to change the interval. No extra hardware is required. The time that a led is "on" is different than the time the led is "off".

• millis_rhythm.ino
  
  Blink a led with a rhytm. The values for the time to set the led on and off are read from an array.

• millis_single_delay.ino
  
  A single "delay" with millis(). A better name is "a single shot timer". A software timer is started. When the time is up, the software timer stops itself, thus creating a single event.

• millis_clock.ino
  
  A clock with hours, minutes and seconds. The serial monitor is used as output to show the time.

• millis_count_down.ino
  
  Counting down with millis().

• millis_short_press_long_press.ino
  
  Press a button for a short time to turn a led on, and press the button for a long time to turn the led off.

• millis_short_press_long_press_extra.ino
  
  This sketch does exactly the same as "millis_short_press_long_press.ino" but a finite state machine is used. The compiled code uses less memory, but the source code is harder to understand.

• millis_within_millis.ino
  
  Using millis() to blink a led, and another millis() software timer to turn on and off the blinking.

• millis_within_millis_extra.ino
  
  The same as "millis_within_millis.ino", but with extra specific working. The led does not turn off immediately, but it turns off at the end of its "on" time. That is done by using a extra (buffered) boolean variable.

• millis_measure_time.ino
  
  Use millis() and micros() to measure how long a piece of code takes. Measure for example how long the function analogRead() takes in three different ways.

• millis_soft_pulsating_led.ino
  
  A led with soft pulsating brightness. The brightness is updated with millis() with a fixed interval.
  A led and a resistor is needed, and a PWM pin is used.

• millis_led_heartbeat.ino
  
  A led that blinks softly like a heartbeat, using millis() to update the brightness.
  A led and a resistor is needed, and a PWM pin is used.

• micros_software_PWM.ino
  
  Instead of millis(), the micros() function is used to create a software PWM signal. The brightness of a led (on any pin) can be set by entering a value in the serial monitor.

• millis_and_bool.ino
  
  A boolean variable can be used to do something just once. It can also be used to turn something on and off by pressing the same button.

• millis_and_finite_state_machine.ino
  
  This example sketch combines millis(), boolean variables and a finite state machine.

• millis_serial_timeout.ino
  
  Use millis as a timeout when receiving serial data to make it possible that data is received with or without a carriage return or linefeed.

• millis_reaction_timer.ino
  
  Measure how fast your reaction time is. Using millis and a finite state machine.

• millis_timestamp_events.ino
  
  Copy events from a button to a led with a delay of two seconds. This example shows how to timestamp events with millis().

• millis_overdone.ino
  
  This sketch runs 400 millis timers at the same time on a Arduino Uno, or 7000 millis timers on a Arduino Zero or MKR board, or 27000 on a ESP32 board.

• Too_Much_For_One_Button.ino
  
  Use a single button to select more than 40 different commands.

These examples are in the Public Domain, because they are only small and basic examples for using millis().

Maybe in the future I will add a few more:
Play a tune without delay, using millis() and a "update" function as an alternative for the ToneMelody example. That might already exist: https://github.com/nathanRamaNoodles/Noodle-Synth , https://github.com/end2endzone/NonBlockingRTTTL and https://github.com/ArduinoGetStarted/buzzer .
Increase a value with acceleration when a button is kept pressed.
Run millis timers with priority, run some always and others when there is still time.