LCD problem with 16F628

[ngeronikolos]

Good morning to everybody,

I have a problem with my code.LCD--->16F628

Please check my code!!!
Thnks


' PicBasic program to demonstrate operation of an LCD in 4-bit mode
'
' LCD should be connected as follows:
' LCD PIC
' DB4 PortA.0
' DB5 PortA.1
' DB6 PortA.2
' DB7 PortA.3
' RS PortA.4 (add 4.7K pullup resistor to 5 volts)
' E PortB.3
' RW Ground
' Vdd 5 volts
' Vss Ground
' Vo 20K potentiometer (or ground)
' DB0-3 No connect
@ DEVICE pic16F628, INTRC_OSC_NOCLKOUT ' system clock options
@ DEVICE pic16F628, WDT_ON ' watchdog timer
@ DEVICE pic16F628, PWRT_ON ' power-on timer
@ DEVICE pic16F628, MCLR_OFF ' master clear options (internal)
@ DEVICE pic16F628, BOD_ON ' brown-out detect
@ DEVICE pic16F628, LVP_OFF ' low-voltage programming
@ DEVICE pic16F628, CPD_OFF ' data memory code Protect
@ DEVICE pic16F628, PROTECT_OFF ' program code protection


Define LCD_BITS 4 ' 4-bit interface
Define LCD_LINES 2 ' 2 line LCD

' LCD should be connected as follows:
' LCD PIC
' DB4 PortA.0
' DB5 PortA.1
' DB6 PortA.2
' DB7 PortA.3
Define LCD_DREG PORTA
Define LCD_DBIT 0

' RS PortA.4 (add 4.7K pullup resistor to 5 volts)
Define LCD_RSREG PORTA
Define LCD_RSBIT 4

' E PortB.3
Define LCD_EREG PORTB
Define LCD_EBIT 3

' RW Ground
' Vdd 5 volts
' Vss Ground
' Vo 20K potentiometer (wire wiper to Vo, adjust for contrast)
' DB0-3 No connect

Define LCD_COMMANDUS 2000 ' Adjust for slower LCD modules
Define LCD_DATAUS 50

INCLUDE "MODEDEFS.BAS"
INTCON = 0 ' Disable interrupts
CMCON = 7
Pause 500 ' Wait for LCD to startup

loop: Lcdout $fe, 1 ' Clear LCD screen
Lcdout "By:Geronikolos" ' Display Hello
Pause 500 ' Wait .5 second

Lcdout $fe,$c0,"World" ' Clear LCD screen
Pause 500 ' Wait .5 second

Lcdout $fe,$c0,"Hello" ' Clear LCD screen
Pause 500 ' Wait .5 second

Goto loop ' Do it forever

[Melanie]

You might want to try these two things...

1. Ground D0-D3 on the LCD

Don't leave those lines not connected and floating - it's bad practice.

2. Increase the inital Pause 500 to Pause 1000

Pause 500 may be insufficient for your LCD to initialise at power-on.

Why don't you want to use A.5 for E-Bit? That way the whole of PORTB is free for your applications use. If you used A.6 for the RS Bit, you wouldn't need that Resistor either.

Additionally, although this has nothing to do with the LCD... INTCON = 0 is unnescessary as Interrupts are disabled by default.

[ngeronikolos]

Melanie,

Thanks for your advice but nothing.I ground D0-D3 on the LCD and I change the inital Pause to 1000 and 1500.

I saw on my lcd all first line with black blocks.

Please advice

[Melanie]

1. Check the SPELLING of your LCD Defines... they must be EXACT because the compiler will not flag errors if have made a mistake there.

2. Check that you have not mistakenly swapped your E or RS bits and connected them the wrong way around...

3. Turn down your contrast... if it's too high then you might be swamping any displayed data with black blocks.

4. Finally, double-check your hardware connections against your DEFINES.

There are no problems or issues connecting LCDs to a 16F628 on internal oscillator with internal MCLR therefore it must be something in your connection...

[ngeronikolos]

The compiler is OK.No errors.

May my programmer cause the problem?
Because the circuit and the program was working in the past.

Thanks

[ngeronikolos]

Melanie,

I check my circuit and it seems ok.
That is the diargam of it.

Please have a look.

[technotronix]

Please see below thread discussion. This may help you.
https://www.ccsinfo.com/forum/viewtopic.php?t=42284