LCD display not working properly

[dilpkan]

I am trying to write a simple code to enable password entry. I am using 16F877a and two line LCD module for display. I have written following code which gets compiled successfully however when I key in four digits they are not displayed on the LCD module.

OPTION_REG.7 = 0 ' PORTB Pullups.
TrisA = 0 ' PORTA, all outputs
PortA = 16 ' Turn off Buzer
TrisB = %11110000 ' PORTB.0-3 outputs, 4-7 inputs
PortB = 0
Define LCD_DREG PORTC
Define LCD_DBIT 0
Define LCD_RSREG PORTC
Define LCD_RSBIT 4
Define LCD_EREG PORTC
Define LCD_EBIT 5

LD1 var PortA.2
RL1 var PortA.3
BUZ var portA.4
cnt var byte
cnt2 var word

key var byte
col var byte
row var byte
keycnt var byte
pwOK var bit

keybuf var byte[15]
pwbuf var byte[4]
Pause 100 ' Wait for LCD to start

Lcdout $fe, 1, " HELLO " ' Display sign on message
Lcdout $fe, 1, " WORLD " ' Display sign on message

Pause 500 ' Wait for LCD to start

Lcdout $fe, 1, "Enter pasaward " ' Display sign on message

loop: Gosub Chk_KEYPAD: ' Get a key from the keypad
Lcdout $fe, $c0+1,1,$0f, #key ' Display ASCII key number
Gosub Chk_KEYPAD: ' Get a key from the keypad
Lcdout $fe, $c0+2,1,$0f, #key ' Display ASCII key number
Gosub Chk_KEYPAD: ' Get a key from the keypad
Lcdout $fe, $c0+3,1,$0f, #key ' Display ASCII key number
Gosub Chk_KEYPAD: ' Get a key from the keypad
Lcdout $fe, $c0+4,1,$0f, #key ' Display ASCII key number

Goto loop ' Do it forever

[bbazor]

I didn't see a Chk_KEYPAD subroutine included in your code. Do you have one?

[scarroll01]

If this is for password entry, do you even WANT to display the characters that are entered? Better to handle it like MS Windows and display asterisks.

Just a thought,
... Steve.

[dilpkan]

If this is for password entry, do you even WANT to display the characters that are entered? Better to handle it like MS Windows and display asterisks.

Just a thought,
... Steve.

Thanks for replying

I accept your suggestion ! however how to get the four asterisks in four positions in one line

Please suggest

dilpkan

[dilpkan]

I didn't see a Chk_KEYPAD subroutine included in your code. Do you have one?

Chk_KEYPAD subroutine has been used at gosub

The problem is that the four numbers are not displayed at 1st , 2nd , 3rd ,4th positions in one line

thanks for replying

dilpkan

[skimask]

Chk_KEYPAD subroutine has been used at gosub
The problem is that the four numbers are not displayed at 1st , 2nd , 3rd ,4th positions in one line
thanks for replying
dilpkan

Let's analyze one of your LCDOUT statements...

Lcdout $fe, $c0+1,1,$0f, #key

LCDOUT - the command
$fe - send an instruction
$c0 + 1 - the position
1 - clear the display which basically resets the display back to square one
$0f - programmable character
#key - a variable
....
See a problem here?

[dilpkan]

Let's analyze one of your LCDOUT statements...



LCDOUT - the command
$fe - send an instruction
$c0 + 1 - the position
1 - clear the display which basically resets the display back to square one
$0f - programmable character
#key - a variable
....
See a problem here?

I deleted "1 " -(clear the display...) and tried the above code using gosub four times for the four diff. positions but the display shows a question mark at 16th position on first line and stops. why?

please help.

dilpkan

[skimask]

I deleted "1 " -(clear the display...) and tried the above code using gosub four times for the four diff. positions but the display shows a question mark at 16th position on first line and stops. why?

please help.

dilpkan

Increase the startup pause to 1 second...increase your LCD_commandus and LCD_dataus to higher values, try it again and see what happens.