'----------------------------------------------------------------------------------------
'    Name:  4x4_KEYBOARD_MATRIX.TIG
'    Type:  Tiger-BASIC(tm) Source Code
' Purpose:  Reading up to 4 x 4 keys from a free Tiger 8-bit port
'
'  (C) - Copyright Wilke Technology, P.O.Box 1727, D-52018 Aachen, Germany
'----------------------------------------------------------------------------------------
'
' Thank you for using BASIC Tigers in your products. If you have questions, ideas
' or special needs, please contact your next distributor or the Tiger support team
' and visit our web site:
'
'	Wilke Technology GmbH
'	The Tiger Support Team
'	P.O.Box 1727,       D-52018 Aachen, Germany
'	Krefelder Str. 147, D-52070 Aachen, Germany
'
'	email: support@wilke-technology.com  (english)
'	email: support@wilke.de              (german)
'	Phone: +49 (241) 918 900    Mo to Fr, 7:00 to 16:00 (GMT)
'	Fax:   +49 (241) 918 9068
'
' New information, new drivers and free downloads see:
'
'	www.wilke-technology.com	     (english)
'	www.wilke.de                         (german)
'
' Sincerely,
'
'	Your Tiger Support Team
'
'----------------------------------------------------------------------------------------
'
'
' This program demonstrates how to read a 4 x 4 keyboard matrix from a
' Tiger I/O port (here: port 8) without any additional components.
'
' Please connect the keyboard matrix to the Tiger module like this:
'
'                Minimal Keyboard
'
'         P80_____|_____|_____|_____|_
'                \|    \|    \|    \|
'                 |     |     |     |
'         P81_____|_____|_____|_____|_
'                \|    \|    \|    \|
' 4 x in          |     |     |     |
'         P82_____|_____|_____|_____|_
'                \|    \|    \|    \|
'                 |     |     |     |
'         P83_____|_____|_____|_____|_
'                \|    \|    \|    \|
'                 |     |     |     |
'                 |     |     |     |
'               P84   P85   P86   P87
'
'                4 x out (1 active)
'
'
' The program uses a task to continuously scan port 8 for pressed keys
' and if a key is pressed, a corresponding character is written into
' the keyboard buffer (a string variable). From your main program, you
' ask if there are characters in the buffer, read characters as needed
' and then delete the read characters from the buffer. To avoid
' unwanted characters when waiting for e.g. data entry, you can erase
' the buffer before the entry routine.
' Only single keys are read, if you press two keys simultaneously, the
' second is ignored until the first is released. There is no keyboard
' auto-repeat, you have to press a key multiple times to get multiple
' characters.
'---------------------------------------------------------------------
USER_VAR_STRICT				' variables must be declared

STRING KEYBUF$(64)			' keyboard buffer (global)


TASK MAIN				' begin task MAIN

BYTE X					'
STRING USER$(100)			'

INSTALL_DEVICE #1, "LCD1.TDD"		' install LCD (4 x 20)

DIR_PORT 8, 255				' all pins as input
OUT 8, 0FFH, 0FFH			' set input pins of port 8 to "pull-up"

KEYBUF$ = ""				' clear keyboard buffer
RUN_TASK SCAN_KEY			' Start task to read keyboard

USER$ = ""				' reset user string
PRINT #1, "<1>";			' clear LCD screen
FOR X = 0 TO 0 STEP 0			' endless loop
  WHILE LEN(KEYBUF$) <> 0		' s.th. in keyboard buffer?
    USER$ = LEFT$(KEYBUF$, 1)		' read "oldest" character
    PRINT #1, USER$;			' output it on LCD
    KEYBUF$ = RIGHT$ (KEYBUF$, LEN(KEYBUF$)-1) ' delete it from buffer
  ENDWHILE				'
NEXT					' end of endless loop

END					' end of task MAIN



'---------------------------------------------------------------------
' This task continuously checks the port 8 for pressed keys
'---------------------------------------------------------------------
TASK SCAN_KEY				' start task SCAN_KEY

BYTE EVER, X, KEY_NO, OLD_KEY_NO	'
BYTE BITVAL, INVAL, OUTVAL		'
STRING KEYS$(16)			'

KEYS$ = "ABCDEFGHIJKLMNOP"		' the 16 keys of the keyboard,
					' starting with key no. 0
OLD_KEY_NO = 255			' set compare to "no key"
WAIT_NEXT 30				' initialize 30 ms wait

FOR EVER = 0 TO 0 STEP 0		' endless loop
  WAIT_NEXT				' release task time

  FOR X = 4 TO 7			' bits for keyboard columns
    BITVAL = EXP (2, X)			' Create value for bit x (16, 32, 64 or 128)
    OUTVAL = 255 - BITVAL		' Create mask for DIR_PORT (239, 223, 191, 127)
    DIR_PORT 8, OUTVAL			' Set new pin directions

    OUT 8, 255, 255 - BITVAL		' Set output pin "low" = 0, all others "high" = 1
    IN 8, INVAL				' read port 8
    INVAL = INVAL BITAND 15		' use only lower 4 bits
    SWITCHI INVAL			'
      CASE 15: KEY_NO = 255		' no key in column pressed
      CASE 14: KEY_NO = ((X-4)*4)	' calculate key no.
               X = X - 1		' same column again
      CASE 13: KEY_NO = ((X-4)*4) + 1	' calculate key no.
               X = X - 1		' same column again
      CASE 11: KEY_NO = ((X-4)*4) + 2	' calculate key no.
               X = X - 1		' same column again
      CASE 7:  KEY_NO = ((X-4)*4) + 3	' calculate key no.
               X = X - 1		' same column again
      DEFAULT: X = X - 1		' same column again
    ENDSWITCH				'

    IF KEY_NO <> OLD_KEY_NO THEN	' if new key(value) detected
      OLD_KEY_NO = KEY_NO		' save it for comparing
      IF KEY_NO <> 255 THEN		' if not "no key"
        KEYBUF$ = KEYBUF$ + MID$(KEYS$, KEY_NO, 1) ' add key to keyboard buffer
      ENDIF				'
    ENDIF				'

  NEXT					' next column
NEXT					' end of endless loop

END					' end of task SCAN_KEY