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adalucio

Joined: 16 Mar 2009
Posts: 29

16f876 and lcd

Posted: Mon May 09, 2011 12:11 pm

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Hi all

I'm trying to use a (working) lcd (20x2) with a 16f876. I have a 20Mhz quartz.

I see only the first line with all square.

DB4 - RA2
DB5 - RA0
DB6 - RA1
DB7 - RA4
RS - RB6
RW - RA3
E - RB7

main.c

Code:

#include <main.h>
#include "flex_lcd_16x1.c"

void main()
{
setup_adc_ports(NO_ANALOGS);
setup_adc(ADC_OFF);

delay_ms(100);
lcd_init();
delay_ms(600);

printf(lcd_putc, "\fABCDEFGHIJKLMNOPQRST");
printf(lcd_putc, "\nabcdefghijklmnopqrst");

delay_ms(2000);

while(1)
{
output_high(PIN_B0);
delay_ms(1000);
output_low(PIN_B0);
delay_ms(1000);

printf(lcd_putc, "Test");
}
}

main.h

Code:

#include <16F876.h>

#FUSES NOWDT //No Watch Dog Timer
#FUSES HS //Crystal osc <= 4mhz for PCM/PCH , 3mhz to 10 mhz for PCD
#FUSES PUT //Power Up Timer
#FUSES NOBROWNOUT //No brownout reset
#FUSES NOLVP //No low voltage prgming, B3(PIC16) or B5(PIC18) used for I/O
#FUSES NOCPD //No EE protection
#FUSES NOWRT //Program memory not write protected
#FUSES NODEBUG //No Debug mode for ICD
#FUSES NOPROTECT //Code not protected from reading

#use delay(clock=20000000)

Code:

#define LCD_DB4 PIN_A2
#define LCD_DB5 PIN_A0
#define LCD_DB6 PIN_A1
#define LCD_DB7 PIN_A4

#define LCD_RS PIN_B6
#define LCD_RW PIN_A3
#define LCD_E PIN_B7

Thanks

PCM programmer

Joined: 06 Sep 2003
Posts: 21708

Posted: Mon May 09, 2011 12:17 pm

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Quote:

DB4 - RA2
DB5 - RA0
DB6 - RA1
DB7 - RA4
RS - RB6
RW - RA3
E - RB7

Pin A4 is open-drain on this PIC. It needs an external 4.7K pull-up
resistor on that pin, to operate as an output pin. The LCD has a pull-up
on the DB7 pin, but it's very weak. You should add the external 4.7K
pull-up to it.

Also, you're using pins B6 and B7 for the lcd. Those are the programmer
and debugger pins (for ICD2, ICD3, PicKit, ICD-U40, etc.). The lcd
won't run if the ICD is connected to the board. It's better if you use two
other pins for the lcd.

Quote:

I'm trying to use a (working) lcd (20x2) with a 16f876.
#include "flex_lcd_16x1.c"

Also, you are using the wrong Flex driver. You have a 2-line LCD.
I think the 16x2 Flex driver would work OK for your LCD:
http://www.ccsinfo.com/forum/viewtopic.php?t=24661

adalucio

Joined: 16 Mar 2009
Posts: 29


Posted: Tue May 10, 2011 2:11 am

Thanks it worked

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