Diff: main.cpp

Revision:

1:0c22e424ea51

Parent:

0:d8190262fb61

--- a/main.cpp	Tue Mar 08 20:46:33 2016 +0000
+++ b/main.cpp	Tue Mar 08 21:28:50 2016 +0000
@@ -1,4 +1,83 @@
-
+/* @file   Hotboards_keypad.cpp
+|| @version 1.2
+|| @author Mark Stanley
+|| @contact mstanley@technologist.com
+||
+||  07/11/12 - Re-modified (from DynamicKeypadJoe2) to use direct-connect kpds
+||  02/28/12 - Modified to use I2C i/o G. D. (Joe) Young
+||
+||
+|| @dificulty:  Intermediate
+||
+|| @description
+|| |    This is a demonstration of keypadEvents. It's used to switch between keymaps
+|| |    while using only one keypad.  The main concepts being demonstrated are:
+|| |
+|| |        Using the keypad events, PRESSED, HOLD and RELEASED to simplify coding.
+|| |        How to use setHoldTime() and why.
+|| |        Making more than one thing happen with the same key.
+|| |        Assigning and changing keymaps on the fly.
+|| |
+|| |    Another useful feature is also included with this demonstration although
+|| |    it's not really one of the concepts that I wanted to show you.  If you look
+|| |    at the code in the PRESSED event you will see that the first section of that
+|| |    code is used to scroll through three different letters on each key.  For
+|| |    example, pressing the '2' key will step through the letters 'd', 'e' and 'f'.
+|| |
+|| |
+|| |  Using the keypad events, PRESSED, HOLD and RELEASED to simplify coding
+|| |    Very simply, the PRESSED event occurs imediately upon detecting a pressed
+|| |    key and will not happen again until after a RELEASED event.  When the HOLD
+|| |    event fires it always falls between PRESSED and RELEASED.  However, it will
+|| |    only occur if a key has been pressed for longer than the setHoldTime() interval.
+|| |
+|| |  How to use setHoldTime() and why
+|| |    Take a look at keypad.setHoldTime(500) in the code.  It is used to set the
+|| |    time delay between a PRESSED event and the start of a HOLD event.  The value
+|| |    500 is in milliseconds (mS) and is equivalent to half a second.  After pressing
+|| |    a key for 500mS the HOLD event will fire and any code contained therein will be
+|| |    executed.  This event will stay active for as long as you hold the key except
+|| |    in the case of bug #1 listed above.
+|| |
+|| |  Making more than one thing happen with the same key.
+|| |    If you look under the PRESSED event (case PRESSED:) you will see that the '#'
+|| |    is used to print a new line, Serial.println().  But take a look at the first
+|| |    half of the HOLD event and you will see the same key being used to switch back
+|| |    and forth between the letter and number keymaps that were created with alphaKeys[4][5]
+|| |    and numberKeys[4][5] respectively.
+|| |
+|| |  Assigning and changing keymaps on the fly
+|| |    You will see that the '#' key has been designated to perform two different functions
+|| |    depending on how long you hold it down.  If you press the '#' key for less than the
+|| |    setHoldTime() then it will print a new line.  However, if you hold if for longer
+|| |    than that it will switch back and forth between numbers and letters.  You can see the
+|| |    keymap changes in the HOLD event.
+|| |
+|| |
+|| |  In addition...
+|| |      You might notice a couple of things that you won't find in the Arduino language
+|| |    reference.  The first would be #include <ctype.h>.  This is a standard library from
+|| |    the C programming language and though I don't normally demonstrate these types of
+|| |    things from outside the Arduino language reference I felt that its use here was
+|| |    justified by the simplicity that it brings to this sketch.
+|| |      That simplicity is provided by the two calls to isalpha(key) and isdigit(key).
+|| |    The first one is used to decide if the key that was pressed is any letter from a-z
+|| |    or A-Z and the second one decides if the key is any number from 0-9.  The return
+|| |    value from these two functions is either a zero or some positive number greater
+|| |    than zero.  This makes it very simple to test a key and see if it is a number or
+|| |    a letter.  So when you see the following:
+|| |
+|| |    if (isalpha(key))    // this tests to see if your key was a letter
+|| |
+|| |    And the following may be more familiar to some but it is equivalent:
+|| |
+|| |    if (isalpha(key) != 0)   // this tests to see if your key was a letter
+|| |
+|| |  And Finally...
+|| |    To better understand how the event handler affects your code you will need to remember
+|| |    that it gets called only when you press, hold or release a key.  However, once a key
+|| |    is pressed or held then the event handler gets called at the full speed of the loop().
+*/
 #include "mbed.h"
 #include "Hotboards_keypad.h"
 #include <ctype.h>