Blink_millis2.ino

/*
** Copyright (c) 2021, Bradley A. Minch
** All rights reserved.
**
** Redistribution and use in source and binary forms, with or without
** modification, are permitted provided that the following conditions are met: 
** 
**     1. Redistributions of source code must retain the above copyright 
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**     2. Redistributions in binary form must reproduce the above copyright 
**        notice, this list of conditions and the following disclaimer in the 
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**
** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" 
** AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 
** IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 
** ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE 
** LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 
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*/

const uint8_t LED = 13;               // LED is connected to D13
const uint8_t POT = 0;                // POT wiper is connected to A0

uint16_t blink_interval;              // Global variable to store the blink interval in milliseconds
uint32_t blink_time;                  // Global variable to store the time that LED last changed state

void setup() {
  pinMode(LED, OUTPUT);               // Configure LED pin as a digital output
  digitalWrite(LED, HIGH);            // Set LED high initially
  blink_time = millis();              // Remember the current value of the millis timer
  blink_interval = analogRead(POT);   // Convert potentiometer wiper voltage to initalize blink_interval
}

void loop() {
  uint32_t t;                         // Local variable to store the current value of the millis timer

  t = millis();                       // Get the current value of the millis timer
  if (t >= blink_time + blink_interval) { // If blink_interval milliseconds have elapsed since blink_time,
    digitalWrite(LED, !digitalRead(LED)); //   toggle the state of LED and
    blink_time = t;                       //   set blink_time to the current value of the millis timer
  }

  blink_interval = analogRead(POT);   // Convert potentiometer wiper voltage to update blink_interval
}