a Lcd connected to pic 16f877 in port D doesn't work.

[isa]

hello every one.

I have a question about connecting a LCD to the pic 16F877.

The question is that the LCD works if connected to Port B, but in Port D there is no way to make it works.

Can it be a current problem? Doesn`t port D give enouh mA to the Lcd??Can the problem be relationed with the pull up resistors?

I can do my proyect with the LCD in port B but I would like to Know why in Port D doesn't works.

Thanks
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This message was ported from CCS's old forum
Original Post ID: 10934

[nanard-bis]

You couldn't need the pull up resistor on port d 0x08
for 16f877.
you use the driver #include<lcd.c> for drive your lcd.
because this driver don't run with my lcd (ic ks0066u).



:=hello every one.
:=
:=I have a question about connecting a LCD to the pic 16F877.
:=
:=The question is that the LCD works if connected to Port B, but in Port D there is no way to make it works.
:=
:=Can it be a current problem? Doesn`t port D give enouh mA to the Lcd??Can the problem be relationed with the pull up resistors?
:=
:=I can do my proyect with the LCD in port B but I would like to Know why in Port D doesn't works.
:=
:=Thanks
___________________________
This message was ported from CCS's old forum
Original Post ID: 10939

[isa]

Well, i'm afraid i didn't explain myself very well.

Port B has internal weak pull up resistor, but i don't use it when i connect Lcd to this port. It's no needed.

I've been seing the 16f877 manual and i have seen that port B has ttl levels when configured as input.
The difference between port D is :
Port D has schmitt trigger levels when configured as standart I/O pin, and Ttl when configured as paralell slave port mode.
Port B has ttl levels when configured as standart I/O pin.

It's maybe the source of my problem.

I use LCD PC1602F-B (POWERTIP) AND here you have the LCD code i use, that works ok in port B (but not in D)

////////////////////////////////////////////////////////////////////////////
//// (C) Copyright 1996,1997 Custom Computer Services ////
//// This source code may only be used by licensed users of the CCS C ////
//// compiler. This source code may only be distributed to other ////
//// licensed users of the CCS C compiler. No other use, reproduction ////
//// or distribution is permitted without written permission. ////
//// Derivative programs created using this software in object code ////
//// form are not restricted in any way. ////
////////////////////////////////////////////////////////////////////////////

// As defined in the following structure the pin connection is as follows:
// B0 enable
// B1 rs
// B2 rw
// B4 D4
// B5 D5
// B6 D6
// B7 D7
//
// LCD pins D0-D3 are not used and PIC B3 is not used.

struct lcd_pin_map { // This structure is overlayed
boolean enable; // on to an I/O port to gain
boolean rs; // access to the LCD pins.
boolean rw; // The bits are allocated from
boolean unused; // low order up. ENABLE will
int data : 4; // be pin B0.
} lcd;

#byte lcd = 6 // This puts the entire structure
// on to port B (at address 6)

#define lcd_type 2 // 0=5x7, 1=5x10, 2=2 lines
#define lcd_line_two 0x40 // LCD RAM address for the second line


byte CONST LCD_INIT_STRING[4] = {0x20 | (lcd_type << 2), 0xc, 1, 6};
// These bytes need to be sent to the LCD
// to start it up.


// The following are used for setting
// the I/O port direction register.

STRUCT lcd_pin_map const LCD_WRITE = {0,0,0,0,0}; // For write mode all pins are out
STRUCT lcd_pin_map const LCD_READ = {0,0,0,0,15}; // For read mode data pins are in




byte lcd_read_byte() {
byte low,high;

set_tris_d(LCD_READ);
lcd.rw = 1;
delay_cycles(1);
lcd.enable = 1;
delay_cycles(1);
high = lcd.data;
lcd.enable = 0;
delay_cycles(1);
lcd.enable = 1;
delay_us(1);
low = lcd.data;
lcd.enable = 0;
set_tris_d(LCD_WRITE);
return( (high<<4) | low);
}


void lcd_send_nibble( byte n ) {
lcd.data = n;
delay_cycles(1);
lcd.enable = 1;
delay_us(2);
lcd.enable = 0;
}


void lcd_send_byte( byte address, byte n ) {

lcd.rs = 0;
while ( bit_test(lcd_read_byte(),7) ) ;
lcd.rs = address;
delay_cycles(1);
lcd.rw = 0;
delay_cycles(1);
lcd.enable = 0;
lcd_send_nibble(n >> 4);
lcd_send_nibble(n & 0xf);
}


void lcd_init() {
byte i;

set_tris_d(LCD_WRITE);
lcd.rs = 0;
lcd.rw = 0;
lcd.enable = 0;
delay_ms(15);
for(i=1;i<=3;++i) {
lcd_send_nibble(3);
delay_ms(5);
}
lcd_send_nibble(2);
for(i=0;i<=3;++i)
lcd_send_byte(0,LCD_INIT_STRING[i]);
}


void lcd_gotoxy( byte x, byte y) {
byte address;

if(y!=1)
address=lcd_line_two;
else
address=0;
address+=x-1;
lcd_send_byte(0,0x80|address);
}

void lcd_putc( char c) {
switch (c) {
case '\f' : lcd_send_byte(0,1);
delay_ms(2);
break;
case '\n' : lcd_gotoxy(1,2); break;
case '\b' : lcd_send_byte(0,0x10); break;
default : lcd_send_byte(1,c); break;
}
}

char lcd_getc( byte x, byte y) {
char value;

lcd_gotoxy(x,y);
lcd.rs=1;
value = lcd_read_byte();
lcd.rs=0;
return(value);
}
___________________________
This message was ported from CCS's old forum
Original Post ID: 10948

[Pete Smith]

:=Well, i'm afraid i didn't explain myself very well.
:=
:=Port B has internal weak pull up resistor, but i don't use it when i connect Lcd to this port. It's no needed.
:=
:=I've been seing the 16f877 manual and i have seen that port B has ttl levels when configured as input.
:=The difference between port D is :
:= Port D has schmitt trigger levels when configured as standart I/O pin, and Ttl when configured as paralell slave port mode.
:=Port B has ttl levels when configured as standart I/O pin.
:=
:=It's maybe the source of my problem.
:=
:=I use LCD PC1602F-B (POWERTIP) AND here you have the LCD code i use, that works ok in port B (but not in D)
:=
:=////////////////////////////////////////////////////////////////////////////
:=//// (C) Copyright 1996,1997 Custom Computer Services ////
:=//// This source code may only be used by licensed users of the CCS C ////
:=//// compiler. This source code may only be distributed to other ////
:=//// licensed users of the CCS C compiler. No other use, reproduction ////
:=//// or distribution is permitted without written permission. ////
:=//// Derivative programs created using this software in object code ////
:=//// form are not restricted in any way. ////
:=////////////////////////////////////////////////////////////////////////////
:=
:=// As defined in the following structure the pin connection is as follows:
:=// B0 enable
:=// B1 rs
:=// B2 rw
:=// B4 D4
:=// B5 D5
:=// B6 D6
:=// B7 D7
:=//
:=// LCD pins D0-D3 are not used and PIC B3 is not used.
:=
:=struct lcd_pin_map { // This structure is overlayed
:= boolean enable; // on to an I/O port to gain
:= boolean rs; // access to the LCD pins.
:= boolean rw; // The bits are allocated from
:= boolean unused; // low order up. ENABLE will
:= int data : 4; // be pin B0.
:= } lcd;
:=
:=#byte lcd = 6 // This puts the entire structure
:= // on to port B (at address 6)
:=
:=#define lcd_type 2 // 0=5x7, 1=5x10, 2=2 lines
:=#define lcd_line_two 0x40 // LCD RAM address for the second line
:=
:=
:=byte CONST LCD_INIT_STRING[4] = {0x20 | (lcd_type << 2), 0xc, 1, 6};
:= // These bytes need to be sent to the LCD
:= // to start it up.
:=
:=
:= // The following are used for setting
:= // the I/O port direction register.
:=
:=STRUCT lcd_pin_map const LCD_WRITE = {0,0,0,0,0}; // For write mode all pins are out
:=STRUCT lcd_pin_map const LCD_READ = {0,0,0,0,15}; // For read mode data pins are in
:=
:=
:=
:=
:=byte lcd_read_byte() {
:= byte low,high;
:=
:= set_tris_d(LCD_READ);
:= lcd.rw = 1;
:= delay_cycles(1);
:= lcd.enable = 1;
:= delay_cycles(1);
:= high = lcd.data;
:= lcd.enable = 0;
:= delay_cycles(1);
:= lcd.enable = 1;
:= delay_us(1);
:= low = lcd.data;
:= lcd.enable = 0;
:= set_tris_d(LCD_WRITE);
:= return( (high<<4) | low);
:=}
:=
:=
:=void lcd_send_nibble( byte n ) {
:= lcd.data = n;
:= delay_cycles(1);
:= lcd.enable = 1;
:= delay_us(2);
:= lcd.enable = 0;
:=}
:=
:=
:=void lcd_send_byte( byte address, byte n ) {
:=
:= lcd.rs = 0;
:= while ( bit_test(lcd_read_byte(),7) ) ;
:= lcd.rs = address;
:= delay_cycles(1);
:= lcd.rw = 0;
:= delay_cycles(1);
:= lcd.enable = 0;
:= lcd_send_nibble(n >> 4);
:= lcd_send_nibble(n & 0xf);
:=}
:=
:=
:=void lcd_init() {
:= byte i;
:=
:= set_tris_d(LCD_WRITE);
:= lcd.rs = 0;
:= lcd.rw = 0;
:= lcd.enable = 0;
:= delay_ms(15);
:= for(i=1;i<=3;++i) {
:= lcd_send_nibble(3);
:= delay_ms(5);
:= }
:= lcd_send_nibble(2);
:= for(i=0;i<=3;++i)
:= lcd_send_byte(0,LCD_INIT_STRING[i]);
:=}
:=
:=
:=void lcd_gotoxy( byte x, byte y) {
:= byte address;
:=
:= if(y!=1)
:= address=lcd_line_two;
:= else
:= address=0;
:= address+=x-1;
:= lcd_send_byte(0,0x80|address);
:=}
:=
:=void lcd_putc( char c) {
:= switch (c) {
:= case '\f' : lcd_send_byte(0,1);
:= delay_ms(2);
:= break;
:= case '\n' : lcd_gotoxy(1,2); break;
:= case '\b' : lcd_send_byte(0,0x10); break;
:= default : lcd_send_byte(1,c); break;
:= }
:=}
:=
:=char lcd_getc( byte x, byte y) {
:= char value;
:=
:= lcd_gotoxy(x,y);
:= lcd.rs=1;
:= value = lcd_read_byte();
:= lcd.rs=0;
:= return(value);
:=}
:=
:=
:=
:=
:=
:=
___________________________
This message was ported from CCS's old forum
Original Post ID: 10960

[PaulKlissner]

I'm doing exactly what you're trying to do:
Driving an LCD from Port D with a PIC16F877.

It works perfectly.

Not only do you need to convert the tris lines
in lcd.h to port D instead of port B, as you seem to have
done, but you ALSO need to be sure that the
pin data structure is mapped to port D as well:

Original way:
#byte lcd = 6 // This puts the entire structure // on to port B

Modified way for Port D:
#byte lcd = 8

Did you try that?

-Paul
___________________________
This message was ported from CCS's old forum
Original Post ID: 10996