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noral
Joined: 09 May 2014
Posts: 4
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| Half display on LCD with flex_lcd.c |
 Posted: Tue May 13, 2014 6:41 pm |
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Hi everyone!
I have a problem with the LCD. I've got a Hitachi LM016L 16x2 with a PIC24FJ128GC010. I'm using CCS compiler and the flex_lcd.c driver.
When I try to show a message in the LCD, I can only see half message (only the first 8 characters of each line).
Can anyone help me? 
I share with you my "Hello World" code and the flex_lcd.c code.
Thanks in advance.
main code:
| Code: | #include <24FJ128GC010.H>
#fuses FRC, NOWDT, NOPROTECT, BROWNOUT, ICSP1
#use delay(clock = 8000000)
#include <flex_lcd.c>
//==========================
void main()
{
lcd_init();
delay_ms(1000);
printf(lcd_putc,"\fHello World\n");
lcd_putc("Hola Mundo");
while(1);
}
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flex_lcd.c code:
| Code: |
// flex_lcd.c
// These pins are for the Microchip PicDem2-Plus board,
// which is what I used to test the driver. Change these
// pins to fit your own board.
#define LCD_DB4 PIN_D0
#define LCD_DB5 PIN_D1
#define LCD_DB6 PIN_D2
#define LCD_DB7 PIN_D3
#define LCD_E PIN_A1
#define LCD_RS PIN_A3
//#define LCD_RW PIN_A2
// If you only want a 6-pin interface to your LCD, then
// connect the R/W pin on the LCD to ground, and comment
// out the following line.
//#define USE_LCD_RW 1
//========================================
#define lcd_type 2 // 0=5x7, 1=5x10, 2=2 lines
#define lcd_line_two 0x40 // LCD RAM address for the 2nd line
int8 const LCD_INIT_STRING[4] =
{
0x20 | (lcd_type << 2), // Func set: 4-bit, 2 lines, 5x8 dots
0xc, // Display on
1, // Clear display
6 // Increment cursor
};
//-------------------------------------
void lcd_send_nibble(int8 nibble)
{
// Note: !! converts an integer expression
// to a boolean (1 or 0).
output_bit(LCD_DB4, !!(nibble & 1));
output_bit(LCD_DB5, !!(nibble & 2));
output_bit(LCD_DB6, !!(nibble & 4));
output_bit(LCD_DB7, !!(nibble & 8));
delay_cycles(1);
output_high(LCD_E);
delay_us(2);
output_low(LCD_E);
}
//-----------------------------------
// This sub-routine is only called by lcd_read_byte().
// It's not a stand-alone routine. For example, the
// R/W signal is set high by lcd_read_byte() before
// this routine is called.
#ifdef USE_LCD_RW
int8 lcd_read_nibble(void)
{
int8 retval;
// Create bit variables so that we can easily set
// individual bits in the retval variable.
#bit retval_0 = retval.0
#bit retval_1 = retval.1
#bit retval_2 = retval.2
#bit retval_3 = retval.3
retval = 0;
output_high(LCD_E);
delay_cycles(1);
retval_0 = input(LCD_DB4);
retval_1 = input(LCD_DB5);
retval_2 = input(LCD_DB6);
retval_3 = input(LCD_DB7);
output_low(LCD_E);
return(retval);
}
#endif
//---------------------------------------
// Read a byte from the LCD and return it.
#ifdef USE_LCD_RW
int8 lcd_read_byte(void)
{
int8 low;
int8 high;
output_high(LCD_RW);
delay_cycles(1);
high = lcd_read_nibble();
low = lcd_read_nibble();
return( (high<<4) | low);
}
#endif
//----------------------------------------
// Send a byte to the LCD.
void lcd_send_byte(int8 address, int8 n)
{
output_low(LCD_RS);
#ifdef USE_LCD_RW
while(bit_test(lcd_read_byte(),7)) ;
#else
delay_us(60);
#endif
if(address)
output_high(LCD_RS);
else
output_low(LCD_RS);
delay_cycles(1);
#ifdef USE_LCD_RW
output_low(LCD_RW);
delay_cycles(1);
#endif
output_low(LCD_E);
lcd_send_nibble(n >> 4);
lcd_send_nibble(n & 0xf);
}
//----------------------------
void lcd_init(void)
{
int8 i;
output_low(LCD_RS);
#ifdef USE_LCD_RW
output_low(LCD_RW);
#endif
output_low(LCD_E);
delay_ms(15);
for(i=0 ;i < 3; i++)
{
lcd_send_nibble(0x03);
delay_ms(5);
}
lcd_send_nibble(0x02);
for(i=0; i < sizeof(LCD_INIT_STRING); i++)
{
lcd_send_byte(0, LCD_INIT_STRING[i]);
// If the R/W signal is not used, then
// the busy bit can't be polled. One of
// the init commands takes longer than
// the hard-coded delay of 60 us, so in
// that case, lets just do a 5 ms delay
// after all four of them.
#ifndef USE_LCD_RW
delay_ms(5);
#endif
}
}
//----------------------------
void lcd_gotoxy(int8 x, int8 y)
{
int8 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;
}
}
//------------------------------
#ifdef USE_LCD_RW
char lcd_getc(int8 x, int8 y)
{
char value;
lcd_gotoxy(x,y);
// Wait until busy flag is low.
while(bit_test(lcd_read_byte(),7));
output_high(LCD_RS);
value = lcd_read_byte();
output_low(lcd_RS);
return(value);
}
#endif
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temtronic
Joined: 01 Jul 2010
Posts: 9221
Location: Greensville,Ontario
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| Posted: Tue May 13, 2014 7:43 pm |
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one comment...
please put a
delay_ms(500);
before the lcd_init();
You need to give the LCD module time to 'get organized' before you try to access it.
Some modules need less time, a couple more, but 500ms has always worked for me..
The flex driver has been reliable for several displays.
recode/recompile/retest, report back what happens.
hth
jay |
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notbad
Joined: 10 Jan 2013
Posts: 68
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| Posted: Wed May 14, 2014 1:12 am |
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There is a similar problem with some 16x1 LCDs. Maybe it has something to do with that.
Some 16x1 LCDs have to be configured as 8x2. Take a look at PCM_Programmer's driver for 16x1 LCDs (flex_lcd_16x1.c).
Hope that helps.  |
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noral
Joined: 09 May 2014
Posts: 4
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| Posted: Wed May 14, 2014 2:19 am |
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| temtronic wrote: | one comment...
please put a
delay_ms(500);
before the lcd_init();
You need to give the LCD module time to 'get organized' before you try to access it.
Some modules need less time, a couple more, but 500ms has always worked for me..
The flex driver has been reliable for several displays.
recode/recompile/retest, report back what happens.
hth
jay |
Thanks for your reply Jay
I've retested with this delay before the lcd_init(); but keep showing half screen.
I've tried with 1000ms and 500ms unsuccessfully :( |
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Ttelmah
Joined: 11 Mar 2010
Posts: 19496
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| Posted: Wed May 14, 2014 4:18 am |
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Unfortunately, the best thing to do, would be to start testing with a quick test with a second display!....
The LCD you have uses one of the most 'standard' chipsets (it was the ancestor, that was copied by many others), and should work directly with the flex_lcd driver. However the first question would be 'are you seeing the correct characters in the half of the screen that does display?. If not, you could have one data line not connecting properly.
Then there are two variants of the chip used on different displays. The newer 44780S which directly supports 16*2, and the older 44780U which only directly supports 8*2, until a second expansion chip is added. You might have this second variant, with a faulty expansion chip...
On the different 16*1 version mentioned by 'notbad', some of the 16*1 displays are actually wired internally as an 8*2, and these then need the 8*2 driver. This can't directly apply to the 16*2. |
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temtronic
Joined: 01 Jul 2010
Posts: 9221
Location: Greensville,Ontario
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| Posted: Wed May 14, 2014 4:44 pm |
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Another test you could make on the display you have is to run in in native 8 bit mode. It requires a few more wires(4) but you could then confirm the display does function. Since 1/2 the display doesn't in 4 bit mode it could be a hardware problem and not the driver.
hth
jay |
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