looking for pointers, tips, etc...

[bill12780]

Hello all,

What an adventure this has been! I have completely fallen for this enbedded coding stuff and in paticular PBP. Best money I have spent in a long time. More fun then I have had in a long time...I actully like my job again!

Here is my little project so far...Just the keyboard scan part. Now I know of Mr._E's Keypad.bas include. But I wanted to write my own for educational purposes...

Here is my code...I should mention that the the 3x4 keypad is NOT a standard keypad its custom made for my company. So ignore that there is not "#" or "*"

Also, it is a neccessary for me to get the keypressed one at a time. This is so we can compare the entered code number by number and compare it to the stored number. Rather then using an array or for/next to gather a group of keypresses.

@ DEVICE HS_OSC             
'SET OSC BIT TO HS 


'Defines...

'*lcd defines*
DEFINE LCD_DREG	PORTD	'Define PIC port used for LCD Data lines
DEFINE LCD_DBIT	4	'Define first pin of portd connected to LCD DB4
DEFINE LCD_RSREG PORTD	'Define PIC port used for RS line of LCD
DEFINE LCD_RSBIT 2	'Define Portd pin used for RS connection
DEFINE LCD_EREG	PORTD	'Define PIC port used for E line of LCD
DEFINE LCD_EBIT	3	'Define Portd pin used for E connection
DEFINE LCD_BITS	4	'Define the 4 bit communication mode to LCD
DEFINE LCD_LINES 2		'Define using a 2 line LCD
DEFINE LCD_COMMANDUS 2000	'Define delay time between sending LCD commands
DEFINE LCD_DATAUS 50	             'Define delay time between data sent.

'*other defines*
DEFINE OSC 8          'DEFINE EXTERNAL OCS TO 8MHZ

'setup ports...
INIT:
'TRISC = %00000000       'SETS PORTC TO ALL OUTPUTS (future use)
'PORTC = %00000000      'TURNS ALL OF PORT C OFF (future use)
'OPTION_REG.7=0           'Enable the internal PORTB pullups (this does nt wk)
TRISB = %00001111       'Set Keypad I/O 1=input 0=output
PORTB = 0                    'Set columns LOW 


'setup variables...

key var byte

lcdout $fe, 1			' Clear LCD

main: 'SCAN keypad for key press

colum0:
portb = %00010000   'turn on colum0 for row scan
if portb.1 = 1 then key = 9: goto display
if portb.2 = 1 then key = 6: goto display
if portb.3 = 1 then key = 3: goto display



colum1:
portb = %00100000   'turn on colum1 for row scan
if portb.0 = 1 then key = 0: goto display
if portb.1 = 1 then key = 8: goto display
if portb.2 = 1 then key = 5: goto display
if portb.3 = 1 then key = 2: goto display



colum2:
portb = %01000000   'turn on colum2 for row scan
if portb.1 = 1 then key = 7: goto display
if portb.2 = 1 then key = 4: goto display
if portb.3 = 1 then key = 1: goto display

goto main


DISPLAY:
' LCD Command codes
'------------------
' $01       Clear Display
' $02       home
' $0C       Cursor off
' $0E       Underline cursor on
' $0F       Blinking cursor on
' $10       Move cursor left one character
' $14       Move cursor right one character
' $C0       Move cursor to begining of next line
' all commands must use the format LCDOUT $fe, XX

'Setup LCD...

	lcdout $fe, 1			' Clear LCD 
	lcdout $fe, 2			' Position cursor at home
    lcdout "you pressed..", dec key
    
goto main

Everything works just fine. I am now trying to figure out a good way to debounce. But for now I would love to hear from some of you more advance coders as to how I could make this...Well....more eligante. I looked at the "lookup" command and many examples. I just cant seem to get my head wrapped around how I would impliment it. So if your idea has anything to do with that please include a small tutorial on lookup tables.

I should also mention that this is just test code. I have broken down my project into several steps. I am making one step work then moving on to the next. Eventually, I will have the knowledge to pull them all together. For example, I figured out the LCD stuff....Moved on to the Scanning of the keypad....Next is reading and writing to the internal EEPROM...etc...


Oh...I am using the following apps and chips just as a reference....

PIC16f877a
EasyPIC4 Dev. board (mikroelektronika)
PBP 4.27
PICFlash 4.07 (mikro again)
pm.exe compiler

Your thoughts please ladies and gentlemen...

Best regards,
Bill12780