Entering numbers with OneWireKeypad

Projects Programming
1

My breadboard uses a 3x4 matrix keypad wired up in the usual way with resistors to give a one-wire analog output, together with a 2 line 20 character LCD display. The sketch to check the hardware is shown here (it works).

#include <OnewireKeypad.h> // OneWireKeypad Library
#include <LiquidCrystal.h> // Parallel LCD Library

 
char KEYS[]= {  // Define keys values of Keypad
  '1','2','3',
  '4','5','6',
  '7','8','9',
  '*','0','#'
};
 
OnewireKeypad <Print, 12 > Keypad(Serial, KEYS, 4, 3, A0, 4700, 1000 );
LiquidCrystal lcd(12, 11, 5, 4, 3, 2);
 
void setup ()
{
  Serial.begin(9600);
  lcd.begin(16, 2);
  lcd.clear();
  lcd.print("Key pressed");
}
 
void loop() 
{
  Keypad.SetHoldTime(200);  
  Keypad.SetDebounceTime(50); 
  
  if ((Keypad.Key_State() == 3))  // not pressed = 0, pressed = 1, released = 2,  held = 3
  {  
    char keypress = Keypad.Getkey();  
    int inKey = keypress-'0'; // Convert the character to an integer
         
    lcd.setCursor(13,0);
    lcd.print(inKey);

    while ((Keypad.Key_State())){}  // Stay here while Key is held down
  }
}

When a key is pressed the number appears towards the right of the display. Obviously when a subsequent key is pressed the number overwrites the previous one. To do something useful (in this particular project - the quantity of water to be pumped), I need to enter a number between 1 and 9999 so that the digits shift to the left after being entered. When the number is correctly entered the key "#" (=-13) will tell the program to continue using this value. I've tried various ways to get this to work without success. I figure there must be a (simple) routine way of doing this that I have overlooked. Any advice would be very welcome!

2 
void loop()
{
  Keypad.SetHoldTime(200);  
  Keypad.SetDebounceTime(50);

Is there some reason that you need to set the hold time and debounce time on EVERY pass through loop()? I didn't think so.

Supposed I entered 1, 3, 6, 7, and #. How would YOU construct a number from that? There are several ways, but the simplest is illustrated below:

int val = 0;
val *= 10; // 0
val += 1; // 1

val *= 10; // 10
val += 3; // 13

val *= 10; // 130
val += 6; // 136

val *= 10; // 1360
val += 7; //1367

Hey, there's the #, so the value to use is 1367.

Now, can you figure out how to code that?

3

PaulS: Thanks for your reply to my posting. I've modified my sketch to include your suggestions. Unfortunately it still doesn't seem to work.
Every time a key is pressed the 'if' statements are executed. However the next time the value of 'val' has been lost.
I would appreciate it if you could help me with this point.

#include <OnewireKeypad.h> // OneWireKeypad Library
#include <LiquidCrystal.h> // Parallel LCD Library

 
char KEYS[]= {  // Define keys values of Keypad
  '1','2','3',
  '4','5','6',
  '7','8','9',
  '*','0','#'
};
 
OnewireKeypad <Print, 12 > Keypad(Serial, KEYS, 4, 3, A0, 4700, 1000 );
LiquidCrystal lcd(12, 11, 5, 4, 3, 2);
 
void setup ()
{
  Keypad.SetHoldTime(100);  
  Keypad.SetDebounceTime(50); 
  Serial.begin(9600);
  lcd.begin(16, 2);
  lcd.clear();
  lcd.print("Key pressed");
}
 
void loop() 
{
  int val;  
  if ((Keypad.Key_State() == 3))  // not pressed = 0, pressed = 1, released = 2,  held = 3
  {  
    char keypress = Keypad.Getkey();  
    int inKey = keypress-'0';
         
    lcd.setCursor(13,0);
    lcd.print(inKey);
    while ((Keypad.Key_State())){}  // Stay here while Key is held down

    val *= 10;
    val += inKey;
    lcd.clear();
    lcd.print(val);
  }
}
4

However the next time the value of 'val' has been lost.

void loop() 
{
  int val;

Not lost, but reinitialised
Try

void loop() 
{
  static int val = 0;

or make val a global variable.

5

UKHeliBob: Thanks for pointing out the difference between global variables, static variables and variable scope. I should have studied this before, but now I'm sure I'm on the right track. My only excuse - a mis-spent youth programming in BASIC!

6

No excuse - C++ just seems like fancy BASIC with ; to me.
MrsCrossroads cringes everytime I say that 8)

I declare all my variables as global - no getting caught out of scope for me!