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Krazzy7434
Joined: 21 Aug 2014
Posts: 39
Location: India
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| 16X4 Lcd displaying unreadable characters with Pic18f4550 |
 Posted: Thu Aug 21, 2014 1:51 am |
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Hey GUYS........
I'm new to pic programming and to this forum. I'm trying to program a pic18f4550 which receives data from virtual terminal(isis) and display it on a 16x4 lcd display....But it displays unreadable characters like α α α α
HERE is my prgm:
| Code: |
#include <18f4550.h>
#fuses HSPLL,NOWDT,NOPROTECT,NOLVP,NODEBUG,USBDIV,PLL5,CPUDIV1,VREGEN,NOPBADEN
#use delay(clock=48000000)
#use rs232(baud=56000, xmit=PIN_C6,parity=N,rcv=PIN_C7,ERRORS,bits=8)
#include <flex_lcd416.c>
void main()
{
for(;;)
{
lcd_init();
lcd_setcursor_vb(1,1);
lcd_putc("Receving Data\n");
delay_ms(1000);
if(kbhit())
{
printf(LCD_PUTC,"%c",getch());
delay_ms(500);
output_high(PIN_A0);
delay_ms(500);
}
else
{
output_low(PIN_A0);
delay_ms(100);
}
}
}
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Here is my LCD Driver:
| 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_B4
#define LCD_DB5 PIN_B5
#define LCD_DB6 PIN_B6
#define LCD_DB7 PIN_B7
#define LCD_RS PIN_C0
#define LCD_RW PIN_C1
#define LCD_E PIN_C2
// 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
void lcd_setcursor_vb(short visible, short blink) {
lcd_send_byte(0, 0xC|(visible<<1)|blink);
}
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here is the output:
PLZZZ HELP ME GUYS.....
_________________
Krazzy7434 |
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temtronic
Joined: 01 Jul 2010
Posts: 9229
Location: Greensville,Ontario
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| Posted: Thu Aug 21, 2014 5:29 am |
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a few things, not all....
1) is this REAL hardware or just an ISIS 'simulation'?
2) 56000 baud is non standard,PC may not be able to generate it withn spec
3) have you correctly wired a MAX232 or equal from PIC to PC?
4)you _must_ add a delay_ms(500); BEFORE the LCD_INIT() function in main()
5)lcd driver is 2 line NOT 4 line
6)schematic doesn't show power or contrast properly connected
7) LCD_init(); should NOT be in the forever loop
recode/recompile/retest/report back
jay |
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Krazzy7434
Joined: 21 Aug 2014
Posts: 39
Location: India
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| Posted: Thu Aug 21, 2014 9:29 am |
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| temtronic wrote: | a few things, not all....
1) is this REAL hardware or just an ISIS 'simulation'?
2) 56000 baud is non standard,PC may not be able to generate it withn spec
3) have you correctly wired a MAX232 or equal from PIC to PC?
4)you _must_ add a delay_ms(500); BEFORE the LCD_INIT() function in main()
5)lcd driver is 2 line NOT 4 line
6)schematic doesn't show power or contrast properly connected
7) LCD_init(); should NOT be in the forever loop
recode/recompile/retest/report back
jay |
1)First of all very very thanks for the reply...... 
2)secondly its an isis simulation for the time being..not tested on a hardware..but soon i have the hardware..
3)i did exactly as you have said...but the output is same....
4)Could you please suggest a good lcd driver for 16x4 lcd...
Thank you....
_________________
Krazzy7434 |
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temtronic
Joined: 01 Jul 2010
Posts: 9229
Location: Greensville,Ontario
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| Posted: Thu Aug 21, 2014 9:47 am |
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there is a 4x20 driver in the 'code library' here, courtesy of PCM programmer or Mr. Ttelmah. It should work fine though may need modifying as you say you have a 16 x 4 LCD.
You need to KNOW that ISIS is full of bugs, errors, and faulty DRCs and CANNOT be trusted as a working, functional 'simulator'. There are dozens of 'threads' here about it's 'quirks' and how programs 'work' in ISIS but NOT in the real world. No one here has the time to rewrite ISIS to be correct and frankly you are far better off getting real PIC and hardware and working on the bench and not in the virtual world.
while I've only got about 20 years with PICs I've never found a 'simulator' that actually works properly.EVERY one fails simple tests I toss at it.
Once you get your real PIC and test, come on back.
hth
jay |
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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| Posted: Thu Aug 21, 2014 3:49 pm |
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I tested it in hardware (with a 20x4 lcd) and it does work at 48 MHz.
But I suggest adding these two fuses for a more reliable PIC start-up:
I used the 20x4 lcd driver (not the 16x2, as you are doing):
http://www.ccsinfo.com/forum/viewtopic.php?t=28268 |
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Krazzy7434
Joined: 21 Aug 2014
Posts: 39
Location: India
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| Posted: Fri Aug 22, 2014 12:32 am |
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| PCM programmer wrote: | I tested it in hardware (with a 20x4 lcd) and it does work at 48 MHz.
But I suggest adding these two fuses for a more reliable PIC start-up:
I used the 20x4 lcd driver (not the 16x2, as you are doing):
http://www.ccsinfo.com/forum/viewtopic.php?t=28268 |
Thanks for the reply PIC Programmer...
I tried the 4x16 lcd driver and test program for lcd written by you. The test program worked perfectly..... ...But when i used getc() the lcd is not displaying anything....but without getc() it works perfectly....
This is what i added.....
| Code: |
char ch;
ch=getc();
if (kbhit())
{
printf(lcd_putc,"%c",ch);
}
|
Specifically when getch() is used lcd wont work....!!! 
_________________
Krazzy7434 |
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Ttelmah
Joined: 11 Mar 2010
Posts: 19520
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| Posted: Fri Aug 22, 2014 1:09 am |
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The code you have is backwards.....
| Code: |
char ch;
//Do put this at the start of the code section, not inline
ch=getc(); //This will wait for a character to be available, then get it
if (kbhit()) //This will therefore always be 'false', since the previous
//line has read the character, so one is no longer waiting.....
{
printf(lcd_putc,"%c",ch);
}
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Krazzy7434
Joined: 21 Aug 2014
Posts: 39
Location: India
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| Posted: Fri Aug 22, 2014 1:48 am |
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| Ttelmah wrote: | The code you have is backwards.....
| Code: |
char ch;
//Do put this at the start of the code section, not inline
ch=getc(); //This will wait for a character to be available, then get it
if (kbhit()) //This will therefore always be 'false', since the previous
//line has read the character, so one is no longer waiting.....
{
printf(lcd_putc,"%c",ch);
}
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|
Thanks for the reply...
okay i got it...i changed it to......
| Code: |
if (kbhit())
{
ch=getc();
printf(lcd_putc,"%c",ch);
}
|
still not working....
i did find my problem with my lcd.
my lcd wont working with following statement.............
1)#use rs232(baud=56000, xmit=PIN_C6,parity=N,rcv=PIN_C7,ERRORS,bits=8)
2)getc();
Any IDEA....  [/code]
_________________
Krazzy7434 |
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temtronic
Joined: 01 Jul 2010
Posts: 9229
Location: Greensville,Ontario
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| Posted: Fri Aug 22, 2014 5:51 am |
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As I said in my original post 56000 baud is NOT a standard baudrate ! When the UART is configured,the speed is either 1 or 3% out of spec.Assuming the PC comport is similar, you can easily be 6% out of spec for timing and it won't communicate properly if at all. This is all based on using REAL hardware though I think you're still 'simulating' in ISIS.
Not knowing your actual hardware configuration makes it difficult to debug.
Everyone here _knows_ ISIS is not reliable though.
hth
jay |
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Krazzy7434
Joined: 21 Aug 2014
Posts: 39
Location: India
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| Posted: Fri Aug 22, 2014 7:06 am |
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| temtronic wrote: | As I said in my original post 56000 baud is NOT a standard baudrate ! When the UART is configured,the speed is either 1 or 3% out of spec.Assuming the PC comport is similar, you can easily be 6% out of spec for timing and it won't communicate properly if at all. This is all based on using REAL hardware though I think you're still 'simulating' in ISIS.
Not knowing your actual hardware configuration makes it difficult to debug.
Everyone here _knows_ ISIS is not reliable though.
hth
jay |
Thanks for the reply temtronic......
Actually i have ordered a pic18f4550...including dev board and all necessary items. It is on its way....it takes couple of days to reach me. Right now i dont want to waste my time.. thats why I'm using isis..
Thank you....
_________________
Krazzy7434 |
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Ttelmah
Joined: 11 Mar 2010
Posts: 19520
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| Posted: Fri Aug 22, 2014 8:53 am |
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So, have you tried using one of the standard baud rates?. 57600.
Remember that the virtual terminal needs a MAX232 to drive the PIC. Just like a 'real' PC. |
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Krazzy7434
Joined: 21 Aug 2014
Posts: 39
Location: India
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| Posted: Fri Aug 22, 2014 9:34 am |
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| Ttelmah wrote: | So, have you tried using one of the standard baud rates?. 57600.
Remember that the virtual terminal needs a MAX232 to drive the PIC. Just like a 'real' PC. |
I dont know how to enable serial communication with Pin C6
and Pin C7. Do serial communication possible with with other pins other than pin C6 and pin C7??
_________________
Krazzy7434 |
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Krazzy7434
Joined: 21 Aug 2014
Posts: 39
Location: India
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| Posted: Fri Aug 22, 2014 10:27 am |
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Hey Guys Finally it worked ....................
I removed my lcd from port C to Port D and removed UART1 from #use 232()
Here is my final program::
| Code: |
#include <18f4550.h>
#fuses HSPLL,NOWDT,NOPROTECT,NOLVP,NODEBUG,USBDIV,PLL5,CPUDIV1,VREGEN,NOPBADEN,BORV45,PUT
#use delay(clock=48000000)
#use rs232(baud=9600,xmit=PIN_C6,parity=N,rcv=PIN_C7,ERRORS,bits=8)
#include <flex_lcd416.c>
#include <kbd.c>
void main()
{
int p;
lcd_init();
lcd_setcursor_vb(1,1);
lcd_putc("Receving Data\n");
delay_ms(1000);
for(;;)
{
output_high(PIN_A0);
p=getc();
lcd_putc(p);
delay_ms(100);
printf("Data Send");
delay_ms(100);
}
}
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i m Thankful to All the Guys who help me.....thank u very much guys...
_________________
Krazzy7434 |
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