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Constants

 
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rfjhh



Joined: 31 Mar 2011
Posts: 51
Location: Mexico

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Constants
PostPosted: Wed Mar 13, 2019 2:51 pm     Reply with quote
I am trying to modify the LCD420.c library to work with port D but I have found things that I do not understand:

How should I interpret the following sequence?
Code:
struct lcd_pin_map const LCD_READ = {0,0,0,0,15};

BYTE lcd_read_byte() {
      BYTE low,high;
      set_tris_d([b]LCD_READ[/b]);
      .
      .
      .
      .
temtronic



Joined: 01 Jul 2010
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PostPosted: Wed Mar 13, 2019 6:45 pm     Reply with quote
my copy of the driver has this..
// 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
...

Note the //comment at the end. It makes 4 pins of the I/O data direction register (TRISx) to be inputs, thus allwoing the PIC to READ the data from the LCD module.

I would have preferred ... LCD_READ = {0,0,0,0,1,1,1,1}, as it 'shows' the format better, at least to me.

hope this helps
Jay
PCM programmer



Joined: 06 Sep 2003
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Re: Constants
PostPosted: Wed Mar 13, 2019 7:25 pm     Reply with quote
rfjhh wrote:

I am trying to modify the LCD420.c library to work with port D


1. Change the following line:
Quote:
#locate lcd = getenv("SFR:PORTB")

to this:
Code:
#locate lcd = getenv("SFR:PORTD")


2. In the following routine, notice the two lines in bold:
Quote:
BYTE lcd_read_byte() {
BYTE low,high;

set_tris_b(LCD_READ);
.
.
.
.
.

set_tris_b(LCD_WRITE);
return( (high<<4) | low);
}

Change them to:
Code:
set_tris_d(LCD_READ);
and
Code:
set_tris_d(LCD_WRITE);


3. In this routine, notice the line in bold:
Quote:
void lcd_init() {
BYTE i;

set_tris_b(LCD_WRITE);
lcd.rs = 0;
lcd.rw = 0;

Change it to:
Code:
set_tris_d(LCD_WRITE);
Jerson



Joined: 31 Jul 2009
Posts: 126
Location: Bombay, India

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Re: Constants
PostPosted: Wed Mar 13, 2019 8:39 pm     Reply with quote
rfjhh wrote:

How should I interpret the following sequence?
Code:
struct lcd_pin_map const LCD_READ = {0,0,0,0,15};

      set_tris_d([b]LCD_READ[/b]);
      .
      .


LCD_READ is a structure mapped onto a byte value. the value shown is 0x0F. So, the statement set_tris_d(LCD_READ) will be seen as set_tris_d(0x0F)
rfjhh



Joined: 31 Mar 2011
Posts: 51
Location: Mexico

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Problem fixed
PostPosted: Wed Mar 13, 2019 10:50 pm     Reply with quote
Thanks all of you, PCM specially, now it's working well. Laughing
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