digispark - 2 pin push button to iterate through an hashmap

Question

I'm trying to create a project with my digispark where i can iterate through an hashmap, when i press the push button the digispark writes via digikeyboard the values from an hashmap. Each time i press the button it's supposed to write the first value, then i press the push button again and in the same line it cleans what was written in the first value and writes the second value and so on. when the last value is reached it goes again to the first value if the button is pressed. Right now i'm trying to put the iterator to work preperlly, this is the code i have:

#include "DigiKeyboard.h"
#include "HashMap.h"

HashMap<String, String> hashMap;
int i = 0;

void setup() {
   //setup hashmap
  hashMap.put("key0","test0");
  hashMap.put("key1","test1");
  hashMap.put("key2","test2");
  hashMap.put("key3","test3");
  hashMap.put("key4","test4");

  DigiKeyboard.sendKeyStroke(0);
  pinMode(0, INPUT);
}
void loop() {
  int sensorValue = digitalRead(0);
      while(sensorValue ==1 and i < hashMap.count())
      { 
        delay(100);
        DigiKeyboard.println( hashMap.valueAt(i));
        i++;
      } 
}

when i plug the digispark it prints automatically the first and the second value ("test0" "test1") and every time i press the button i get nothing.

This is my configuration: http://cdn.instructables.com/FZA/0UN8/HI3TXV8D/FZA0UN8HI3TXV8D.LARGE.jpg

Can anyone help me please?

Answer 1

1. Even with a "clean" button, your while() loop will whip through all 5 hashmap values before you can release the button.

2. Switches and button aren't clean. They will (appear to) bounce, sending many pulses before they settle down to a fully on or fully off state. Read Nick Gammon's tutorial on de-bouncing switches.

3. I'm not familiar with your display but if it is a one-line display, and you .println() at it, will the newline character "scroll" the line of text off the display? This could explain why you didn't at least see the final line. You may need a plain .print() call in order not to do that.

4. Most LCD displays have a set of control codes to clear it, move the cursor, etc., which you would have to embed into the text string you send, or send using separate .print() calls. I don't see any provision in your code for including or sending those, so you'll need to fix that, too.
   Right now, I expect your display receives something like
   
   test0\ntest1\ntest2\ntest3\ntest4\n
   
   It probably needs to see something more like
   
   \033Etest0
   
   , e.g., for the first one, etc. That cruft at the beginning of the string is the VT52-code,
   escE, for "Clear the display". (I have no idea what command set your display uses, but the VT-52 commands have been in use for ... um, hmmph! well, a long time, anyway. :) You'll probably to replace it with whatever your particular device uses.

Answer 2

thank you all. i've manage to found a solution to my problem with this code, probably is not the most elegant way to do it but it works:

#include "DigiKeyboard.h"
#include "HashMap.h"

HashMap<char*, char*> hashMap;
int i = 0;
bool flag;

const byte switchPin = 0;
byte oldSwitchState = HIGH;  // assume switch open because of pull-up resistor
const unsigned long debounceTime = 100;  // milliseconds
unsigned long switchPressTime;  // when the switch last changed state

void setup ()
  {
  pinMode (switchPin, INPUT_PULLUP);

     //setup hashmap
  hashMap.put("key0","test0");
  hashMap.put("key1","test1");
  hashMap.put("key2","test2");
  hashMap.put("key3","test3");
  hashMap.put("key4","test4");

  DigiKeyboard.sendKeyStroke(0);

  }  // end of setup

void loop ()
  {
  // see if switch is open or closed
  byte switchState = digitalRead (switchPin);

  // has it changed since last time?
  if (switchState != oldSwitchState)
    {
    // debounce
    if (millis () - switchPressTime >= debounceTime)
       {
       switchPressTime = millis ();  // when we closed the switch 
       oldSwitchState =  switchState;  // remember for next time 
       if (switchState == HIGH)
          {
            delay(500);
            flag = true;
           while(i < hashMap.count() and flag == true)
            {  
              DigiKeyboard.println( hashMap.valueAt(i));
              i++;
              flag = false;
              }
          }  // end if switchState is LOW           
       }  // end if debounce time up

    }  // end of state change

  // other code here ...

  }  // end of loop