16f688 lcd connection


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  1. #1
    Join Date
    Dec 2010
    Posts
    48

    Arrow 16f688 lcd connection

    Hey all, I'm trying to write a program so I can use a LCM1602A lcd screen with a pic 16f688. Here are datasheets for both components:

    lcd - http://www.vintagecomputercables.com...02A-FL-YBW.pdf

    16f688 - http://ww1.microchip.com/downloads/e...Doc/41203B.pdf

    I believe the lcd is a HD44780 equivalent...but I'm not 100% sure. I have everything wired correctly to the best of my knowledge, but all I'm seeing on the screen are 16 black boxes across the top line. I'm using this website as guidance.

    http://embedded-lab.com/blog/?p=203

    I cannot take credit for this code, but this is the code I am using (how do I post my codes in the nice scrolling box?). Thanks to everyone for your help.
    Code:
    LED  var porta.2
    
    TRISC.0 = 0 '(pin 10) Blue Lcd Data bit 4
    TRISC.1 = 0 '(pin 9) White Lcd Data bit 5
    TRISC.2 = 0 '(pin 8) Green Lcd Data bit 6
    TRISC.3 = 0 '(pin 7) Orange Lcd Data bit 7
    TRISC.4 = 0 '(pin 6) Orange/Black Lcd Register select
    TRISC.5 = 0 '(pin 5) Blue/White Lcd Enable bit
    
    ' PIC Hardware Definitions (ie Pin-Out & Port Assignments)
    ANSEL = 0 ' all pins are digital
    CMCON0 = 7 ' turn off comparators
    ADCON0 = 0
    ADCON1 = 0
    
    'pin connection from pic chip to LCD
    '1 VDD 5V
    '2 OSC1 Crystal (internal 4MHz)
    '3 OSC2 Crystal (internal 4MHZ)
    '4 MCLR Pulled up
    '5 RC5 E LCD
    '6 RC4 RS LCD
    '7 RC3 DB7
    '8 RC2 DB6
    '9 RC1 DB5
    '10 RC0 DB4
    '11 RA2 LED pin
    '12 RA1 NC
    '13 RA0 NC
    '14 VSS Ov
    
    'Define LCD registers and bits
    DEFINE OSC 4 'Internal oscillator 4MHz
    DEFINE LCD_DREG PORTC 'Define PIC port used for LCD Data lines
    DEFINE LCD_DBIT 0 'LCD Data Starting Bit = Bit 0 or 4
    DEFINE LCD_EREG PORTC 'Define PIC port used for E line of LCD
    DEFINE LCD_EBIT 5 'Define Port pin used for E connection
    DEFINE LCD_RSREG PORTC 'Define PIC port used for RS line of LCD
    DEFINE LCD_RSBIT 4 'Define Port pin used for RS connection
    DEFINE LCD_BITS 4 'Define the 4 bit communication mode to LCD
    DEFINE LCD_LINES 2 'Define using a 2 line LCD
    DEFINE LCD_COMMANDUS 2000 'Define delay time between sending LCD commands
    DEFINE LCD_DATAUS 50 'Define delay time between data sent.
    
    Pause 500 ' Wait for LCD to startup
    
    loop: 
    
    high led
    pause 200
    low led
    
    Lcdout $fe, 1 ' Clear LCD screen
    Lcdout "Hello" ' Display Hello
    Pause 500 ' Wait .5 second
    
    Lcdout $fe, 1 ' Clear LCD screen
    Lcdout "World" 'Display World
    Pause 500 ' Wait .5 second
    
    Goto loop ' Do it forever
    Last edited by Archangel; - 9th December 2010 at 02:25.

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