absolute number

antonis · 2010-06-04 06:05

hello to everybody!!!!!!!!
i have a numeric kaypad and i enter a 4-digit code.

i have a master code store in a variable and i want to compare with tha and if is thet to do an action

example:
master_code=1234
when i enter the 4-digits i entered one by one and stored in a temporary variable and transfered to eeprom
so ihave in four eeprom places one digit & one digit & one digit & one digit (1 & 2 & 3 & 4)
how i can saidto bs2 take that four digit put in one variable and compare?

thank you!

W9GFO · 2010-06-04 06:12

number = (digit1 * 1000) + (digit2 * 100) + (digit3 * 10) + digit4

Rich H

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The Simple Servo Tester, a kit from Gadget Gangster.

metron9 · 2010-06-04 13:25

or use a loop to directly test each number stored in memory against a stored array.

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Think Inside the box first and if that doesn't work..
Re-arrange what's inside the box then...
Think outside the BOX!

Chris Savage · 2010-06-04 19:36

It's not effifient or a good idea to store incoming data directly into the EEPROM regularly. You do that when you're initially setting the code or something, but for general input and comparison you want to stick to RAM since the EEPROM cells have a limited write cycle lifetime.

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Chris Savage

Parallax Engineering
·

metron9 · 2010-06-05 03:21

I think though Chris if I may point out, input from a keyboard performed by a human for a numeric keypad used to accept a 4 digit code perhaps used a few times per day would last a lifetime even if only 4 eeprom locations were used.
using a rotating algorithm with 40 bytes could last ten lifetimes.

You should perhaps store the codes in eeprom and then store the input into ram space to compare though as Chris suggests. that way you can have many codes to compare input for different users for example.

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Think Inside the box first and if that doesn't work..
Re-arrange what's inside the box then...
Think outside the BOX!

Chris Savage · 2010-06-07 05:06

metron9,

You're correct in that the likelihood of this particular use isn't likely to cause any issues in and of itself, it tells me that programmer is getting comfortable using the EEPROM in place of RAM which could cause problems in many other situations. If you develop your code to use the right resources the first time then you can re-use it later, comfortable in the knowledge that it will work.

You also have to think of the possibility of there being an error in the switch input of code that causes data to be written in a continuous loop. It's the little things that I notice sometimes. Take care all.

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Chris Savage

Parallax Engineering
·

Beau Schwabe · 2010-06-07 07:12

antonis,

"...how i can saidto bs2 take that four digit put in one variable and compare?..."

Why not store the incoming keypad data in one 16-bit variable (WORD)? ... If you can keep the value of each 'key' between 0 and 15, then on each new keypress you can just shift the data left by one nibble and enter the new key on the least significant nibble.

Example Code

Note: on the first itteration the DEBUG window should say "WRONG CODE!!!" ... following that after a false or 'simulated' key pad entry the DEBUG window will display "Code Matches!!"

' {$STAMP BS2}
' {$PBASIC 2.5}

key     VAR Nib
oldkey  VAR Nib

Master  CON $1234    '<- Master Code ; entered as a HEX value (notice the $ at the beginning
Code    VAR Word

'------------------------------------------------------
'------------------------------------------------------
'Test Only!!! - simulates key entry loop
Code=Code<<4
Code=Code+1    '<- same as entering in a "1"
Code=Code<<4
Code=Code+2    '<- same as entering in a "2"
Code=Code<<4
Code=Code+3    '<- same as entering in a "3"

'Used to trigger Key entry loop below
key = 4        '<- pre-loads the 'key' variable as if you entered a "4" on the keyboard.  
oldkey = 0

'------------------------------------------------------
'------------------------------------------------------


MainLoop:
  DEBUG HEX Master,TAB,HEX Code

  IF Master = Code THEN
     DEBUG TAB,"Code matches!!"
  ELSE
     DEBUG TAB,"WRONG CODE!!!"
  ENDIF

  DEBUG CR

'Key Entry Loop
'----------------------------
' Get new key value HERE
'----------------------------
  IF key<>oldkey THEN
     W0=W0<<4
     W0=W0+key
  ENDIF
  oldkey = key
'----------------------------

GOTO MainLoop

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Beau Schwabe

IC Layout Engineer
Parallax, Inc.

Post Edited (Beau Schwabe (Parallax)) : 6/7/2010 7:19:19 AM GMT

perception13 · 2010-07-22 16:09

Beau Schwabe,

your post

Example Code

Note: on the first itteration the DEBUG window should say "WRONG CODE!!!" ... following that after a false or 'simulated' key pad entry the DEBUG window will display "Code Matches!!"

end of post

I'm not sure I understand why its getting the correct code...
How should it be wired?

Thanks in advance

absolute number

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