Reading keypad/checking for key press in setup function

Using Arduino Programming Questions
1

Hi.
Is there a way to check if a key is pressed while in setup function?

I'm using a 4*4 keypad.

Using if keypressed didn't work, so i tried to read the state of pins used for the keypad (so if a state is HIGH i can say a key is pressed).

When checking the states with digitalRead(), i get 1,1,1 and 1 for rows and fluctuating values of columns (i can get 0,0,0,0 ; 0,1,1,0; or even 1,1,1,1 without pressinng any key).

So i can't see how can i check if a keypad is pressed while in setup function.

Any ideas? thanks.

2

hi fjtheknight,

You'll have to post your code for us to help. We need to see it to make sure that you have set things up correctly.

Click on the </> button above the edit window and paste your code in the block.

3

When you call getKey(), it determines if any key is pressed AT THAT INSTANCE. It does NOT wait for a key to be pressed. Are you expecting that it will?

4

To add to Paul's comment. If you need to wait, just use getKey in a while loop till a key is pressed.

5

Hey, thanks for the quick reply.

patduino:
hi fjtheknight,

You'll have to post your code for us to help. We need to see it to make sure that you have set things up correctly.

Click on the </> button above the edit window and paste your code in the block.

My code is a little bit big. The keypad is is working fine whith every thing in loop function :slight_smile:

PaulS:
When you call getKey(), it determines if any key is pressed AT THAT INSTANCE. It does NOT wait for a key to be pressed. Are you expecting that it will?

That's why i tied to check if a column digital pin is HIGH (=keypressed in that column) at that exact moment (so if you are pressing while the program checks, it will read a HIGH value),but as mentioned before, i didn't get a constant LOW value if all keys are not pressed. Maybe that's related to the keypad library.

6

sterretje:
To add to Paul's comment. If you need to wait, just use getKey in a while loop till a key is pressed.

Thanks for your suggestion. What i want to achieve is something like that:

void setup() {

if (keypressed) {
change some conditions//else keep default values

}

void loop() {

do somthing with those conditions
}

I think i can do that in loop function, but i wanted to make it in setup function (so it feels like you set your conditions before you start working :smiley: )

7

I think i can do that in loop function, but i wanted to make it in setup function (so it feels like you set your conditions before you start working :smiley: )

byte key = keypad.getKey();
while(key == NO_KEY)
{
   key = keypad.getKey();
}

Or, you could use the waitForKey() method. 8)

8 
void setup()
{
...
...
bool keypressed.=false;

while(millis() < 5000)
{
  if(keypad.getKey() != NO_KEY)
  {
    keypressed = true;
    break;
  }
}
if(keypressed == true)
{
  ...
  ...
}

This will give around 5 seconds (depending how long the code before it takes) to press a key.

Not compiled or tested.

9

PaulS:

byte key = keypad.getKey();

while(key == NO_KEY)
{
  key = keypad.getKey();
}




Or, you could use the waitForKey() method. 8)

Thanks for the suggestion, ut waitForKey() method stops everything until a key is pressed, i just need to change some variales values if key is pressed and work with default values if not.

sterretje:

void setup()

{
...
...
bool keypressed.=false;

while(millis() < 5000)
{
  if(keypad.getKey() != NO_KEY)
  {
    keypressed = true;
    break;
  }
}
if(keypressed == true)
{
  ...
  ...
}



This will give around 5 seconds (depending how long the code before it takes) to press a key.

Not compiled or tested.

I think that's what i'm looking for :slight_smile: will try it quickly. Thanks

10

sterretje:

void setup()

{
...
...
bool keypressed.=false;

while(millis() < 5000)
{
  if(keypad.getKey() != NO_KEY)
  {
    keypressed = true;
    break;
  }
}
if(keypressed == true)
{
  ...
  ...
}



This will give around 5 seconds (depending how long the code before it takes) to press a key.

Not compiled or tested.

Hey. That worked :smiley: thanks ^^