Need Help LCD 16x2

[chin0609]

Im using flex_lcd in my PIC16F877A but i only show black block?
here my code
flex_lcd.c
// 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_B4
#define LCD_DB5 PIN_B4
#define LCD_DB6 PIN_B6
#define LCD_DB7 PIN_B7

#define LCD_E PIN_B3
#define LCD_RS PIN_B2
#define LCD_RW PIN_B1

// 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

main code
#include <16F877A.H>
#use delay (clock=20000000) // 20MHz
#define LCD_POWER PIN_B0
#include <flex_lcd.c>
#FUSES HS,NOWDT, NOPROTECT, BROWNOUT, NOLVP, PUT
#use rs232 (baud=9600, xmit=PIN_C6, rcv=PIN_C7) //serial

#define SERVO1 PIN_c1
#define led_green PIN_d1
#define led_red PIN_d0
int8 i; // looping

void nocar()
{

for (i=0;i<30;i++) //0 deg
{
output_low(led_green);
output_high(led_red);

output_high(SERVO1);
delay_us(1500);
output_low(SERVO1);
delay_ms(18);
}
lcd_init();
lcd_putc("\fDoor Closed");
}

void car()
{

for (i=0;i<30;i++) // 90 deg
{

output_low(led_red);
output_high(led_green);


output_high(SERVO1);
delay_us(2000);
output_low(SERVO1);
delay_ms(18);
}
lcd_init();
lcd_putc("\fDoor Opened");
}

void main()
{
output_high(LCD_POWER); // Turn on power to LCD
output_low(LCD_RW);

while(1)
{
if(input(PIN_C0)) //Sensor input

{ nocar(); }


else

{ car(); }

}
}

[PCM programmer]

Fix this:

[chin0609]

I'm changed still come out black block.

[albal]

I don't think you mean to wire RW to GND. You should have it connected to PORTB2.

I would once again go over your physical connections and check that there are correct and valid against your declarations in your C code.

[temtronic]

RW can go to ground..it's the '6 pin' wiring for common LCDs that you use in 'write only'(please read comments at the top of the flex driver).I've done it for years, and I currently have an 877 with 2x16 LCD in this mode.
BTW you typically only need .5 volts for VEE, so the pot only needs to be a little above ground.
Also try connecting LCD VDD(+5v) directly to +5V,not controlled by I/O pin B0.

oh and add 'errors' to your use rs232(...) options otherwise the UART buffer with trap out and stall.

[chin0609]

my lcd only display black block only even i adjusted pot.

any wrong in my main code ?
i am new in ccs c..anyone can help me check the main code and lcd?

[temtronic]

Ok...best to start over and just test the LCD without the other code...
something like....

[chin0609]

[temtronic]

Ok...I downloaded the schematic of the PicDem-2 board and found your problem.
You have to redefine the correct pins for the onboard LCD. PicDem uses port D NOT B for the LCD connections.
Simply alter the flex_lcd driver to use the correct pins. I'd rename this new version to say 'picdem2_lcd.c' to keep the original 'safe'.
Be sure to include the new version NOT the original !
Also note that Microchip use a pin to control the voltage to the LCD, be sure to set that pin high to provide power to the LCD.A simple output_high(...) will do the job !

[PCM programmer]

[chin0609]

followed the plain flex_lcd still get the same result

[PCM programmer]

[chin0609]

http://imageshack.us/photo/my-images/546/20110915133012.jpg/

black block
http://imageshack.us/photo/my-images/23/20110915133809.jpg/

[temtronic]

OK....I've confirmed it is NOT a basic driver or hardware problem.

I've used your pin assignments..
// modified flex_lcd.c

#define LCD_DB4 PIN_B4
#define LCD_DB5 PIN_B5
#define LCD_DB6 PIN_A1
#define LCD_DB7 PIN_A2

#define LCD_E PIN_B1
#define LCD_RS PIN_B3
#define LCD_RW PIN_B2 //not used !

with LCD_RW pin(5) on LCD tied to ground( write only mode).
This is how I always wire LCDs as I do not need to read from them.

Hooked up to my trusty 16F877 with 20MHz xtal and it works fine
I do have fixed resistors on the LCD Vee pin3,about .5volts.

So the problem is NOT the flex_LCD driver,unless you've changed something other than the pin assignments.

[PCM programmer]

Post another photo of your LCD that is in focus and a close-up,
and that shows all the pins. I am beginning to suspect that you have
solder shorts between the pins, or you may picked the wrong side of
the connector as "pin 1". If you post a clear photo of the pins and wires
connected to them, then maybe it will show the problem.

Also, your schematic shows "switch" on the MCLR pin. Do you have a
pull-up resistor on MCLR ? You need one. Usually it's a 10K resistor to +5v.

Have you measured the voltage on the contrast pin of the LCD ?
It should be set to about 0.5 volts.