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RodP
Joined: 25 Jun 2005
Posts: 2
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| LCD problems |
 Posted: Sat Jul 02, 2005 8:54 am |
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Hello to all,
I'm trying to get a 2-line 20 character LCD to work with my old PicDem - 2 (not plus) board. It works with PicBasic but I can't make it work with CCS C. The LCD driver program I'm enclosing was written by Mark and I've made the necessary pin changes, correctly I think. Any help would be greatly appreciated!
Rod
| Code: | ////////////////////////////////////////////////////////////////////////////
//// LCDD.C ////
//// Driver for common LCD modules ////
//// ////
//// lcd_init() Must be called before any other function. ////
//// ////
//// lcd_putc(c) Will display c on the next position of the LCD. ////
//// The following have special meaning: ////
//// \f Clear display ////
//// \n Go to start of second line ////
//// \b Move back one position ////
//// ////
//// lcd_gotoxy(x,y) Set write position on LCD (upper left is 1,1) ////
//// ////
//// lcd_getc(x,y) Returns character at position x,y on LCD ////
//// ////
////////////////////////////////////////////////////////////////////////////
//// (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. ////
////////////////////////////////////////////////////////////////////////////
// This structure is overlayed onto the data ports so that you may use
// whatever ports you desire
struct lcd_pin_map
{
BOOLEAN dummy; // PinA0 is not used
BOOLEAN enable; // PinA1
BOOLEAN rw; // PinA2
BOOLEAN rs; // PinA3
int unusedA : 4; // The rest of portA
int unusedB; // portB is not used
int unusedC; // portC is not used
int unusedD : 4;// \ Changed so lower nibble of portd is unused
int data ; // / and upper nibble is data
} lcd;
#if defined(__PCH__)
#locate lcd = 0xF80
#else
#locate lcd = 5
#endif
struct lcd_tris_map
{
BOOLEAN dummy; // PinA0 is not used
int control : 3;
int unusedA : 4; // The rest of portA
int unusedB: 8; // portB is not used
int unusedC: 8; // portC is not used
int unusedD: 4; // \
int data : 4;// / Change to use the upper nibble of portd for data instead of the lower
} lcdtris;
#if defined(__PCH__)
#locate lcdtris = 0xF92
#else
#locate lcdtris = 0x85
#endif
#define set_tris_lcd(x) lcdtris.data = (x); lcdtris.control = 0;
#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] = {0x28, 0xd,1,6};
//BYTE const LCD_INIT_STRING[4] = {0x20 | (lcd_type << 2), 0x0d, 1, 6};
BYTE const LCD_INIT_STRING[4] = {0x20 | (lcd_type << 2), 0xf, 1, 6};// Cursor underlined and blinking
// 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.
#define LCD_WRITE 0 // For write mode all pins are out
#define LCD_READ 15 // For read mode data pins are in
BYTE lcd_read_byte() {
BYTE low,high;
set_tris_lcd(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_lcd(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_lcd(LCD_WRITE);
lcd.rs = 0;
lcd.rw = 0;
lcd.enable = 0;
delay_ms(15);
for(i=1;i<=3;++i) {
lcd_send_nibble(3);// send 3 - threes
delay_ms(5);
}
lcd_send_nibble(2);// 4 bit mode
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);
}
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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| Posted: Sun Jul 03, 2005 4:50 pm |
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| Quote: | and I've made the necessary pin changes, correctly I think
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I see one problem in your modifications to the structure below.
You want to move the data bits onto the upper nybble of Port D,
but you haven't followed the motif. You've left off the " :4" on your
"int data" statement. By doing so, you've forced the data to go
onto the next byte address, which would be Port E.
| Code: | struct lcd_pin_map
{
BOOLEAN dummy; // PinA0 is not used
BOOLEAN enable; // PinA1
BOOLEAN rw; // PinA2
BOOLEAN rs; // PinA3
int unusedA : 4; // The rest of portA
int unusedB; // portB is not used
int unusedC; // portC is not used
int unusedD : 4;// Changed so lower nibble of portd is unused
int data ; // / <--- PROBLEM HERE
} lcd; |
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RodP
Joined: 25 Jun 2005
Posts: 2
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| Thanks PCM |
| Posted: Mon Jul 04, 2005 11:58 am |
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Thank's to PCM for the help. Upon looking deeper into this I see changing the structures is only part of what needs to be done.
I really wish CCS would write a driver that could put the data lines on either the upper or lower 4 bits of a a selected port and the control lines on any pins of another port. PicBasic has this type setup and it works right out of the box! |
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Mark
Joined: 07 Sep 2003
Posts: 2838
Location: Atlanta, GA
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| Posted: Mon Jul 04, 2005 2:20 pm |
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| Not really. I didn't have to change any of the code. That was my goal. Just the struct overlayment needs to be changed. |
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