LCD problems when EBIT is changed

[passion1]

I am using a 28pin PIC16F73 (compatible with 16F877).

If I connect my pic to a LCD using PORTB pin 3 as the EBIT, my LCD works perfectly.

DEFINE LCD_DREG PORTA
DEFINE LCD_DBIT 0
DEFINE LCD_RSREG PORTA
DEFINE LCD_RSBIT 4
DEFINE LCD_EREG PORTB
DEFINE LCD_EBIT 3
DEFINE LCD_BITS 4
DEFINE LCD_LINES 2
DEFINE LCD_COMMANDUS 2000
DEFINE LCD_DATAUS 50


TRISB=0 ' PORTB is output
TRISA=0 ' PORTA is output

ADCON1 =7 ' PORTA is digital


However, I need PORTB to connect a keypad and if I now change the EBIT definition to PORTA pin5:

DEFINE LCD_EREG PORTA
DEFINE LCD_EBIT 5

and move the connection to RA5, then my LCD suddenly won't work?

I have tried anything but cannot understand why this is happening.

[passion1]

My circuit looks exactly like the one on p.96 of the PBP manual that shows the default setup for connecting a LCD. (except for the fact that I am using a pic16f73 and a 20MHz crystal).

Thus default connections for LCD.

Any help or suggestion is appreciated!

[Archangel]

My circuit looks exactly like the one on p.96 of the PBP manual that shows the default setup for connecting a LCD. (except for the fact that I am using a pic16f73 and a 20MHz crystal).

Thus default connections for LCD.

Any help or suggestion is appreciated!

This PIC has a lot of analog stuff, make sure to disable the comparators, and the Capture compare/PWM goodies, also check data sheet RE: SSP Module as that port is used for that , you may have to set registers to disable. Try CMCON = 7 to turn off the comparators.

[BobK]

Hi Passion1,

Did you add a pull up resistor to RA4? It is an open drain type of pin when used in the digital mode.

BobK

[skimask]

Hi Passion1,

Did you add a pull up resistor to RA4? It is an open drain type of pin when used in the digital mode.

BobK

That's true, but he's on RA5...

[BobK]

Hello,

Yes I did understand he is on RA5 and what he is using each pin for but wouldn't the lack of a pull up also affect the proper operation if he didn't have a high level on RA4?

BobK