New to arduino and programming, 4x3 analog keypad question about making a passcode

10 Jan 2013

Hi to you all.I am a 47 year old man who due to an accident am disabled and bought myself an Arduino to keep myself busy. I am new to arduino and have written some basic sketches. and have made some nice projects. I have an UNO R3 board and I have made an analog keypad using 12 tactile buttons and 7 resistors with a 1nf capacitor to help with bouncing. i did this so that all my digital pins are free to use. My idea is to make an alarm system using 2 PIR sensors, 4 LED's, a buzzer and a siren.(I may want to add more components later) I have no problem in writing the code except for the 4x3 keypad. I want to make a passcode eg 1234 but this is the part I am struggling with. The push buttons return a value when they are pressed so how would I go about that part I have written code to serial print the code to my pc and give them a number. please see the code examples below but I have looked all over the internet and asked on the Arduino forum for some help with the keypad. If anyone can help I would appreciate it.

Thank you for taking the time to read this.

void readkeyboard(){
   keyboardValue = analogRead(keyboardPin); // read the value (0-1023)
   if (keyboardValue <25){keypressed = 0;}
   if ((keyboardValue >25) && (keyboardValue < 67)){keypressed = 1;}
   if ((keyboardValue >67) && (keyboardValue < 108)){keypressed = 2;}
   if ((keyboardValue >108) && (keyboardValue < 162)){keypressed = 3;}
   if ((keyboardValue >162) && (keyboardValue < 253)){keypressed = 4;}
   if ((keyboardValue >253) && (keyboardValue < 361)){keypressed = 5;}
   if ((keyboardValue >361) && (keyboardValue < 479)){keypressed = 6;}
   if ((keyboardValue >479) && (keyboardValue < 619)){keypressed = 7;}
   if ((keyboardValue >619) && (keyboardValue < 765)){keypressed = 8;}
   if ((keyboardValue >765) && (keyboardValue < 819)){keypressed = 9;}
   if ((keyboardValue >819) && (keyboardValue < 899)){keypressed = 0;}// this is the * key
   if ((keyboardValue >889) && (keyboardValue < 955)){keypressed = 0;}
   if (keyboardValue >965){keypressed = 0;} // this is the # key

}

when the keys are pressed they return these values

1=58, 2=96, 3=145, 4=228, 5=335, 6=447, 7=598, 8=720, 9=809, *=890, 0=941, #=970

I have Written to the buttons like this just to test the keypad works as it should

   if (keyboardValue >25 && keyboardValue < 67) digitalWrite (12,HIGH);
   if (keyboardValue >67 && keyboardValue < 130) digitalWrite (11,HIGH);
   if (keyboardValue >162 && keyboardValue < 253) digitalWrite (9,HIGH);
   if (keyboardValue >108 && keyboardValue < 162) digitalWrite (10,HIGH);
   if (keyboardValue >253 && keyboardValue < 361) digitalWrite (8,HIGH);

Top Comments

billabott over 13 years ago in reply to e14 Contributor +1

Get some sleep and check out http://www.oomlout.com/a/products/ardx/ tomorrow.

billabott over 13 years ago in reply to e14 Contributor

Here in the US of A, we can get just about any common book thru Inter Library Loan for free at most Public Libraries. Does the UK have that service availlable?
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e14 Contributor over 13 years ago

Hi billabott. Yes you are right. Too many LED's and Supercapacitor charging sketches.
I have been playing with that part of the code all evening and drinking (water).. I just cannot see where I am going wrong. Maybe this dog is too old to learn new tricks after all.
I think I will have to go back to basic programming and try to learn more. When I can afford it I will get myself a book on the Arduino. I have managed the simple things but I want to do more but I am trying to run before I can walk I think.
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billabott over 13 years ago in reply to e14 Contributor

That their pad is different is a Don't Care condition. You can do this; just breathe and drink (water).
Focus your attention on the 20 lines starting with
void loop()
{
...
}
That is the start of the main body of the code. Have you spent much time turning LEDs on and off with the 'Duino?

For testing and debugging the code, it will be useful to write strings to the Serial Monitor using

Serial.println("myValue is ", myValue);
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e14 Contributor over 13 years ago

Hi again the thing is the keypad in that sketch is connected to 7 digital pins and my keypad is connected to 1 analog pin. Or am I missing something fundimentally simple?
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e14 Contributor over 13 years ago

Thank you for your reply billabot I have had a look at the project and if I can work out which parts of the code I need then it might work. I think I might have bitten off a bit more than I can chew here. I feel a headache coming on :-)
I will have a play with the code an see what I can do
Thank you again
Jezza
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