Running an LCD on different port

[malc-c]

Quick question..(hopefully)

In the PBP manual it details the use of PortB to interface with a 2 x 16 LCD.

PBP assumes the LCD is connected to specific pins unless told otherwise. It assumes the LCD will be used with a 4-bit bus with data lines DB4 - DB7 connected to PICmicro PORTA.0 - PORTA.3, Register Select to PORTA.4 and Enable to PORTB.3.

It is also preset to initialize the LCD to a 2 line display.

To change this setup, place one or more of the following DEFINEs, all in upper-case, at the top of your PICBASIC PRO™ program:

' Set LCD Data port
DEFINE LCD_DREG PORTB
' Set starting Data bit (0 or 4) if 4-bit bus
DEFINE LCD_DBIT 4
' Set LCD Register Select port
DEFINE LCD_RSREG PORTB

If I wanted to use PORTC for the LCD display on a 16F873A PIC would the following work if the wiring was the same as shown in the manual (obviously substituting RA1 for RC1 etc)?

' Set LCD Data port
DEFINE LCD_DREG PORTC
' Set starting Data bit (0 or 4) if 4-bit bus
DEFINE LCD_DBIT 4
' Set LCD Register Select port
DEFINE LCD_RSREG PORTC

is there anything eles I would need to do to configure PORTC on the PIC other than TRISC=%00000000, for arguments sake disabling the rx / tx on ports RC7 and 6 ?

[mister_e]

Usually i place all LCD DEFINE's at the top even if i use the default pin assignement. It's easier to change later.

DEFINE LCD_DREG PORTC     ' LCD data port 
DEFINE LCD_DBIT 0         ' LCD data starting bit 0 or 4 
DEFINE LCD_RSREG PORTC    ' LCD register select port 
DEFINE LCD_RSBIT 4        ' LCD register select bit 
DEFINE LCD_EREG PORTC     ' LCD enable port 
DEFINE LCD_EBIT 5         ' LCD enable bit 
DEFINE LCD_BITS 4         ' LCD bus size 4 or 8 
DEFINE LCD_LINES 2        ' Number lines on LCD 
DEFINE LCD_COMMANDUS 2000 ' Command delay time in us 
DEFINE LCD_DATAUS 50      ' Data delay time in us

You don't need to disable the USART as he's already disable at POR.

[malc-c]

Thanks steve, that make a lot of sence (Cuts and pastes code in readyness )

[NatureTech]

Hi,

I got some problem with displaying 20 X 4 line LCD which the controller chip is HD 44780.Actually,when i programmed the chip according to the code below,the lcd is not working!.I even checked the PORTB pin and it seems not changing state?.But my board is working as i checked other programs (I2C,SPI) but this one is not working?.I feel weird.This program is actually sample program from Melabs itself.I wired the final 4 bit from lcd to PORTB.0 to PORTB.3 and the EBIT to to PORTD.7 and for sure RSBIT to PORTD.6.
What is my mistake??Do i have to insert more code like LCD lines and delay???PLS HELP!


DEFINE OSC 20



DEFINE LCD_DREG PORTB
DEFINE LCD_DBIT 4 ' 4 bit selected
DEFINE LCD_RSREG PORTD
DEFINE LCD_RSBIT 6 ' Reset Pin
DEFINE LCD_EREG PORTD
DEFINE LCD_EBIT 7 ' Enable Pin


pause 500 ' Insert Delay for LCD to Power_Up.


loop:


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

Lcdout $fe, 1 ' Clear LCD screen
Lcdout "World"
Pause 500 ' Wait .5 second

Goto loop ' Do it forever


YOUR HELP KINDLY ACCEPTED

[mister_e]

Change this

DEFINE LCD_DBIT 4 ' 4 bit selected

to

DEFINE LCD_DBIT 0 ' Databit start at PORTB.0

[NatureTech]

Thanks for Instant reply but...


Although i have changed the bit size from 4 to 0,it still remains the same.It does nothing.I even switch compiling from MPASM to standard compiler and it didn't show any effect at all.All the display line shows blank.


It's a cheap LCD ( LM044L) and it's buggin me a lot.I still wonder why the PIC never do anything.I had no problem compiling other program but not this one.


Any idea?.Pls help.Thanks a lot mister_e

[mister_e]

Make sure the R/W pin is set to GND & play with the contrast Pot

What happen?

What is your PIC #?

Could be the the config fuses as well, make sure you set HS_OSC and LVP_OFF

Did you tied your unused LCD data pin (DB0, DB1, DB2, DB3) to gnd?

And it's suppose to be a 4X20 LCD type.. you may try to add

DEFINE LCD_LINES 4

[NatureTech]

I never tie the unused pin to ground as i belive it can be left floating?.Anyhow i will do it.I use PIC16F877.HS_OSC is set .I always set LVP_OFF (Low Voltage Programming) as it always does.Ok.I will insert : DEFINE LCD_LINES 4 :and see what happens.Not today but for sure tomorrow.



Thanks a lot Steve.You are great.Hope you can help me tommorow too =>.




NatureTech.
Make thing simple,but not simpler.