Storing an input from matrix keypad?

FlBuckeye · 2007-04-21 01:08

I am using a 4x4 matrix keypad and I'm trying to store an input from the keypad subroutine for use in a password checker. I have the keypad working and have a password checker that works using the Debug window. My question is what command or series of commands is necessary to store the input from one subroutine and use it in another?

Mike Green · 2007-04-21 01:31

There isn't really any particular command involved. Subroutines share data by sharing variables. Say you have an input routine that responds to a keypress on the keypad, does the decoding, and leaves its keycode in a variable called 'key'. When the keypad subroutine is finished, it does a RETURN. Unless you change the 'key' variable, that value will remain there. If you call a routine 'password', you can use the value still in 'key' in 'password'.

FlBuckeye · 2007-04-21 02:10

ok then my subroutines and variables appear ok, I think my problem is in the order of the main program. Back to hunting for the problem... Thanks anyway

Mike Green · 2007-04-21 02:42

If you get stuck, I suggest including your program source as an attachment to an explanatory message describing the specifics of what you want to do, what input values were used and what incorrect behaviour / outputs were observed.

FlBuckeye · 2007-04-21 04:19

Ok I'm stuck... I have tried doing this about 3 or 4 diffrent ways and right now I'm just not seeing where I'm messing up.

I am attempting to use a homework board and a 4x4 matrix keypad as a password checker (once I get that part correct I will add more functionality). I can get either part to function fine on their own (keypad displays correct button pressed, and password checker works fine with the debug window and debugin for input). However when I combine the two I am getting one recorded keystroke and I can't seem to get the password checker to stop attempting to check the single keystroke to record the rest of the password.

' {$STAMP BS2}
' {$PBASIC 2.5}
Password DATA "1234" ' Store "secret" password here.

db VAR Bit ' Debounce bit for use by keyScan.
press VAR Bit ' Flag to indicate keypress.
key VAR Nib ' Key number 0-15.
row VAR Nib ' Counter used in scanning keys.
cols VAR INB ' Input states of pins P4-P7.
index VAR Nib ' Index variable.
temp VAR Byte ' Stores single char.
userEntry VAR Byte(4) ' Stores user entered password.

DEBUG "enter Password"

again:

GOSUB keyScan

IF press = 0 THEN again
press = 0

DEBUG userEntry, HEX key, CR

DO
FOR index = 0 TO 3
READ Password + index, temp
IF temp <> userEntry(index) THEN EXIT ' Compare to user input,
NEXT

IF index <> 3 THEN
DEBUG CR, "Password not correct.", CR
ENDIF
LOOP UNTIL index = 3

DEBUG "Password is correct"

GOTO again

keyScan:

FOR row = 0 TO 3
LOW row
key = ~cols
key = NCD key

IF key <> 0 THEN push
INPUT row
NEXT
db = 0
RETURN

push:
IF db = 1 THEN done
db = 1: press = 1
key = (key-1)+(row*4)

LOOKUP key,[noparse][[/noparse]1,2,3,10,4,5,6,11,7,8,9,12,14,0,15,13],key

done:
INPUT row
RETURN

Mike Green · 2007-04-21 04:28

I assume your keyScan works (I didn't look at it since you said it did). Your password checking code probably finds the password incorrect all the time partly because you've got two nested loops (DO/LOOP and FOR/NEXT) that are sort of doing the same thing. I suggest just using the DO/LOOP:

index = 0
DO
   read Password+index,temp
   if temp <> userEntry(index) then passFail
   index = index + 1
LOOP until index = 4
DEBUG "password correct",CR
GOTO again
passFail:
DEBUG "password incorrect",CR
GOTO again

FlBuckeye · 2007-04-21 04:39

well that helped with the constant scrolling problem... now I just seem to still have a problem of it not correctly recording all 4 charcters to be checked. I greatly appreciate the help btw

FlBuckeye · 2007-04-21 04:45

well I got it to wait for all 4 keys now by adding in

userEntry(4) = key

in the keyscan subroutine, but it still says the password is incorrect.

FlBuckeye · 2007-04-21 06:17

still stuck... I'm thinking my problem might be in the way the "password" is stored. I have tried various methods and none of them seem to be working. I have tried:

Password DATA "1234"
Password DATA 1234
Password DATA 1, 2, 3, 4

I even tried specifying byte, and nib...

I'm still stuck with the program not validating the password...

I should have stuck with servos...

Mike Green · 2007-04-21 14:34

1) You should use: Password DATA 1,2,3,4
That's the way you're storing it, each keypress as a number from 1 to 14

2) Your keyScan routine isn't storing the keypresses into 'userEntry', yet
that's where you're looking for the entered information. That's what happens
sometimes when you combine two routines that both work separately, yet
don't work together. You sometimes forget the "glue" where one routine
assumes that things are left one way and the other routine expects that
things are left a slightly different way.

FlBuckeye · 2007-04-21 20:21

Mike Green said...

2) Your keyScan routine isn't storing the keypresses into 'userEntry', yet
that's where you're looking for the entered information. That's what happens
sometimes when you combine two routines that both work separately, yet
don't work together. You sometimes forget the "glue" where one routine
assumes that things are left one way and the other routine expects that
things are left a slightly different way.

hmmm... I thought that's what this was doing that I added in last night... apparently I'm just not quite getting it just yet... thanks for the patience...

Here is what my understanding is of what I need to do...

1. set password variable
2. keyscan
3. store entered variables from keyscan in 'userEntry'
4. compare userEntry variable with password variable

apparently it looks like it is only storing just one of the keypresses before comparing the variables, what do I need to do diffrent to make it store all 4 keys before attempting to check the password?

keyScan:
FOR row = 0 TO 3
LOW row
key = ~cols
key = NCD key
userEntry(4) = key
IF key <> 0 THEN push
INPUT row
NEXT
db = 0
RETURN

push:
IF db = 1 THEN done
db = 1: press = 1
key = (key-1)+(row*4)
RETURN

LOOKUP key,[noparse][[/noparse]1,2,3,10,4,5,6,11,7,8,9,12,14,0,15,13],key

done:
INPUT row
RETURN

Mike Green · 2007-04-21 20:35

Here's something like your code that may work better:

keyScan:
   index = 0
nextKey:
   db = 0
   for row = 0 to 3
      low row
      key = NCD (~ cols)
      if key <> 0 then
         if db = 1 then
            input row
            key = (key-1) + (row*4)
            lookup key,[noparse][[/noparse]1,2,3,10,4,5,6,11,7,8,9,12,14,0,15,13],key
            userEntry(index) = key
            index = index + 1
            if index = 4 then
               return
            endif
            goto nextKey
         endif
         db = 1
      endif
      next
      goto keyScan

FlBuckeye · 2007-04-21 23:45

Well it now works... I created an electronic lock of sorts... (with a little help from mike, thanks!) I'm sure it isn't perfect but it works...

My two big errors were that I needed to loop the key sequence and where I put the line for the userEntry variable below (vs. above) where index incremented.

I have a grayhill 4x4 keypad attached to p0 up to p7
A servo (connected to a mechanical lock) on p12
A bi-color LED connected to p14 and p15

You enter the correct pin and the servo unlocks the lock and the light changes from red to green for about 5 seconds then relocks the lock and light goes green to red.

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

Password DATA     1,2,3,4   ' Store "secret" password here.

db VAR Bit                          ' Debounce bit for use by keyScan.
press VAR Bit                       ' Flag to indicate keypress.
key VAR Nib                         ' Key number 0-15.
row VAR Nib                         ' Counter used in scanning keys.
cols VAR INB                        ' Input states of pins P4-P7.
index VAR Nib                       ' Index variable.
counter VAR Byte
temp VAR Byte                       ' Stores single char.
userEntry VAR Nib(4)               ' Stores user entered password.
index2 VAR Nib



start:
DEBUG "enter Password",CR
LOW 15
HIGH 14

FOR counter = 1 TO 10
PULSOUT 12, 1000
NEXT

userEntry = 0 /4

main:
FOR index2 = 0 TO 3
  DO
    GOSUB keyScan
  LOOP WHILE press = 0
  DEBUG "key pressed = ", HEX key,CR
  press = 0
NEXT
index = 0
GOSUB checkPassword

checkPassword:
DO
READ Password+index,temp
DEBUG DEC temp, " <> ", DEC userEntry(index),CR
IF temp <> userEntry(index) THEN passFail
index = index + 1
LOOP UNTIL index = 4
DEBUG "password correct",CR
GOTO servoLight
GOTO start

passFail:
DEBUG "password incorrect",CR
GOTO start

servoLight:
FOR counter = 1 TO 180
HIGH 15
LOW 14
PULSOUT 12, 500
PAUSE 20
NEXT
GOTO start



keyScan:
FOR row = 0 TO 3
LOW row
key = ~cols
key = NCD key
IF key <> 0 THEN push
INPUT row
NEXT
db = 0
RETURN


push:
IF db = 1 THEN done
db = 1: press = 1
key = (key-1)+(row*4)
LOOKUP key,[noparse][[/noparse]1,2,3,10,4,5,6,11,7,8,9,12,14,0,15,13],key
userEntry(index) = key
index = index + 1

done:
INPUT row ' Disconnect output on row.
RETURN

Post Edited (FlBuckeye) : 4/21/2007 11:49:43 PM GMT

Storing an input from matrix keypad?

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