Keypad interfacing challenge

Question

Hi everyone! I am trying to interface a 4 x 4 keypad with my Arduino UNO. I am able to get it little bit working but not 100% the way i want. I want some keypad buttons to act different from others. So for example, i have 12 buttons that when RELEASED should trigger a particular function. However i want the remaining 4 buttons to trigger a different function when released and keep triggering that function when the keypad buttons are still in PRESSED state. So to give a proper example, I want to press a button on keypad which will wait for a little while and then it should start to increment a value (like increasing speed while the button is in pressed state). I am able to get the RELEASED and HOLD states working from the Arduino keypad library. But HOLD state only triggers once. If i am able to trigger the HOLD state over and over again after some delay, that would solve the problem i believe. Can anyone please help me. #include <Keypad.h>

/**
 Globals
**/
const byte ROWS = 4; // Four rows
const byte COLS = 4; // Four columns

// Define the Keymap
char keys[ROWS][COLS] = {
 {'1', '2', '3', '4'}, /* S1 S2 S3 S4 */
 {'5', '6', '7', '8'}, /* S5 S6 S7 S8 */
 {'A', 'C', 'E', 'G'}, /* F1U F2U ON NC */
 {'B', 'D', 'F', 'H'} /* F1D F2D OFF NC */
};

// Connect keypad ROW0, ROW1, ROW2 and ROW3 to these Arduino pins.
byte rowPins[ROWS] = { 5, 4, 3, 2 };
// Connect keypad COL0, COL1, COL2 and COL3 to these Arduino pins.
byte colPins[COLS] = { 9, 8, 7, 6 };

// Create the Keypad
Keypad keypad = Keypad( makeKeymap(keys), rowPins, colPins, ROWS, COLS );

byte ledPin = 13;
boolean blink = false;

/**
 Setup
**/
void setup() {
 Serial.begin(9600);
 pinMode(ledPin, OUTPUT); // sets the digital pin as output
 digitalWrite(ledPin, HIGH); // sets the LED on

/* Keypad event listener - Interrupt */
 keypad.addEventListener(keypadEvent); //add an event listener for this keypad

}

/**
 Loop
**/
void loop() {

/* Check for keypad */
 keypad.getKey();

if (blink) {
 digitalWrite(ledPin,!digitalRead(ledPin));
 delay(100);
 }
}

//take care of some special events
void keypadEvent( KeypadEvent key ){
 switch ( keypad.getState() ) {
 case PRESSED:
 break;

case RELEASED:
 switch (key) {
 /* TOGGLES */
 case '1':
 case '2':
 case '3':
 case '4':
 case '5':
 case '6':
 case '7':
 case '8':
 Serial.print("SWITCH: ");
 Serial.println(key);
 //toggleSwitch(key);
 break;

/* FAN 1 */
 case 'A':
 Serial.println("FAN 1 UP");
 break;

case 'B':
 Serial.println("FAN 1 DOWN");
 break;

/* FAN 2 */
 case 'C':
 Serial.println("FAN 2 UP");
 break;

case 'D':
 Serial.println("FAN 2 DOWN");
 break;

/* MASTER CONTROLLS */
 case 'E':
 Serial.println("ALL ON");
 break;

case 'F':
 Serial.println("ALL OFF");
 break;

default:
 Serial.print("UNMAPPED: ");
 Serial.println(key);
 break;
 }
 break;

case HOLD:
 switch (key) {
 /* FAN 1 */
 case 'A':
 Serial.println("FAN 1 UP");
 break;

case 'B':
 Serial.println("FAN 1 DOWN");
 break;

/* FAN 2 */
 case 'C':
 Serial.println("FAN 2 UP");
 break;

case 'D':
 Serial.println("FAN 2 DOWN");
 break;
 }
 break;

case IDLE:
 break;
 }
}

void toggleSwitch( char num ) {
 Serial.println(num);
} I want the FAN speeds to increase/decrease when the buttons 'A', 'B', 'C' and 'D' are held pressed.

Robert Peter Oakes · Accepted Answer

You have nothing in the Pressed case therefor no way of knowing when a key is pressed, never mind being held pressed

switch ( keypad.getState() ) {
case PRESSED:
break;

Your trying to perform the actions when the key is released which of course will only work once as there is no longer anything to detect once you have actually released the key

what you need to do it set a variable equal to the key that is pressed. Do this in the pressed case part of the code, take no other action other than setting this variable

in the release case, you clear the variable to an un-used value

in the loop, you check if the variable is set to a value and if it is then perform your chosen task for that key

this means you will have 3 sets of case statements but this can be simplified in the pressed and released case statements to simply recording the key that was pressed and move all the key processing to the main loop

If the keyboard handler can detect multiple keys then you may want a different approach but I doubt it can based on simple matrix keyboards

sudo code will look like this (You will have to code it correctly, this is just to give you the idea)

char mykey = 'x';

loop()

{

if mykey != 'x'

{

switch mykey

{

/* FAN 1 */

case 'A': Serial.println("FAN 1 UP"); break;

case 'B': Serial.println("FAN 1 DOWN"); break;

etc

}

//take care of some special events

void keypadEvent( KeypadEvent key )

{

switch ( keypad.getState() )

{

case PRESSED: mykey = key; break;

case RELEASED: mykey = 'x'; break;

}

you may also have to mess with the loop delay if it increments too fast

Robert Peter Oakes · Answer

so the delay code needs to be different

use something like this (Not full code but an idea)

const long waitDelay = 300; // 300ms

unsigned long waitTime = 0; // place holder for delay

setup()

{

...

waitTime = millis() + waitDelay ;

} // end of setup

loop()

{

... other stuff

if (waitTime < millis()) // timed out so go into the if statement

{

// time expired so do what else you wanted when the delay normally expired like incrementing you fan speed if the button is still pressed

waitTime = millis() + waitDelay ; // reset for the next loop

}

// now do other things that are not based on the loop, with this you will not be slowed down by the old DELAY(nnn) function

// don't used delay function if you don't want to be slowed down, use the above example to have things trigger at a specified interval instead

// Delay() stops ALL processing while it times out.

} // end of loop()