SoftBlink2 Arduino Sketch

This sketch is used by Exercise: Soft Blink.

Full Source Code

The full code is all in one file SoftBlink2.ino.

 1// SoftBlink2 - fades the onboard LED on and off.
 2//
 3// Copyright (c) 2016, Garth Zeglin.  All rights reserved. Licensed under the
 4// terms of the BSD 3-clause license as included in LICENSE.
 5//
 6// This builds upon the SoftBlink1 example to demonstrate more programming
 7// technique.  Please see SoftBlink1 for the basic commentary.
 8
 9// ================================================================================
10// Define the period of the PWM waveform in milliseconds.
11const int PWMPERIOD = 10;
12
13// ================================================================================
14// Configure the hardware once after booting up.  This runs once after pressing
15// reset or powering up the board.
16
17void setup()
18{
19  // Initialize the LED on pin 13 for output.
20  pinMode(LED_BUILTIN, OUTPUT);
21}
22
23// ================================================================================
24// Run one iteration of the main event loop.  The Arduino system will call this
25// function over and over forever.
26
27void loop()
28{
29  // Perform a pattern of brightness ramps, both up and down and with different duration.
30  // These use the LED_ramp() function defined below.
31
32  // basic ramp up and down, full brightness
33  LED_ramp( 1000,  0, 10 );
34  LED_ramp( 1000, 10,  0 );
35
36  // now in double-time
37  LED_ramp(  500,  0, 10 );
38  LED_ramp(  500, 10,  0 );
39  LED_ramp(  500,  0, 10 );
40  LED_ramp(  500, 10,  0 );
41
42  // now in triple-time, using the loop to avoid repetition
43  for (int i = 0; i < 4; i += 1) {
44    LED_ramp(  333,  0, 10 );
45    LED_ramp(  333, 10,  0 );
46  }
47
48  // back to a second, but dimmer
49  for (int i = 0; i < 2; i += 1) {
50    LED_ramp(  1000,  0,  4 );
51    LED_ramp(  1000,  4,  0 );
52  }
53
54  // keep off for a second
55  delay(1000);
56
57  // and repeat
58}
59
60// ================================================================================
61// Define a function to perform a single brightness ramp according to the
62// specified parameters.  It will not return until the full ramp has been
63// performed, i.e., it will delay for the full ramp duration.  This condenses
64// the redundant code found in SoftBlink1 into a modular software building
65// block.
66//
67//   duration - ramp duration in milliseconds
68//   start    - initial pulse duration, in milliseconds, must be no greater than PWMPERIOD
69//   end      - final pulse duration, in milliseconds, must be no greater than PWMPERIOD
70//
71// The basic logic of the loop is the same as in SoftBlink1.
72
73void LED_ramp(int duration, int start, int end)
74{
75  int num_steps = duration / PWMPERIOD;
76  
77  for(int i = 0; i < num_steps; i = i + 1) {
78    int time_on = map(i, 0, num_steps, start, end);
79    int time_off = PWMPERIOD - time_on;
80
81    digitalWrite(LED_BUILTIN, HIGH);  // turn the LED on
82    delay(time_on);                   // wait the specified number of milliseconds
83    digitalWrite(LED_BUILTIN, LOW);   // turn the LED off
84    delay(time_off);                  // wait the specified number of milliseconds
85  }
86}
87
88// ================================================================================