CCS C Library Code : LCD 20x4 Driver

วันที่โพสต์: Feb 03, 2011 1:35:30 AM

CCS C Library Code : LCD 20x4 Driver

โค๊ดไลบรารี่สำหรับขับจอ LCD ขนาด 20 ตัวอักษร จำนวน 4 บรรทัด 

File : Flex_LCD420.c

Complier : CCS C Complier

Purpose : Driver LCD 20 x 4 

การใช้งาน 

// Flex_LCD420.c 

// These pins are for my Microchip PicDem2-Plus board, 

// which I used to test this driver. 

// An external 20x4 LCD is connected to these pins. 

// Change these pins to match your own board's connections. 

#define LCD_DB4   PIN_B3 

#define LCD_DB5   PIN_B4 

#define LCD_DB6   PIN_B6 

#define LCD_DB7   PIN_B7 

#define LCD_RS    PIN_E0 

#define LCD_RW    PIN_E1 

#define LCD_E     PIN_E2 

/* 

// To prove that the driver can be used with random 

// pins, I also tested it with these pins: 

#define LCD_DB4   PIN_D4 

#define LCD_DB5   PIN_B1 

#define LCD_DB6   PIN_C5 

#define LCD_DB7   PIN_B5 

#define LCD_RS    PIN_E2 

#define LCD_RW    PIN_B2 

#define LCD_E     PIN_D6 

*/ 

// If you want only a 6-pin interface to your LCD, then 

// connect the R/W pin on the LCD to ground, and comment 

// out the following line.  Doing so will save one PIC 

// pin, but at the cost of losing the ability to read from 

// the LCD.  It also makes the write time a little longer 

// because a static delay must be used, instead of polling 

// the LCD's busy bit.  Normally a 6-pin interface is only 

// used if you are running out of PIC pins, and you need 

// to use as few as possible for the LCD. 

#define USE_RW_PIN   1      

// These are the line addresses for most 4x20 LCDs. 

#define LCD_LINE_1_ADDRESS 0x00 

#define LCD_LINE_2_ADDRESS 0x40 

#define LCD_LINE_3_ADDRESS 0x14 

#define LCD_LINE_4_ADDRESS 0x54 

// These are the line addresses for LCD's which use 

// the Hitachi HD66712U controller chip. 

/* 

#define LCD_LINE_1_ADDRESS 0x00 

#define LCD_LINE_2_ADDRESS 0x20 

#define LCD_LINE_3_ADDRESS 0x40 

#define LCD_LINE_4_ADDRESS 0x60 

*/ 

//======================================== 

#define lcd_type 2   // 0=5x7, 1=5x10, 2=2 lines(or more) 

int8 lcd_line; 

int8 const LCD_INIT_STRING[4] = 

{ 

 0x20 | (lcd_type << 2),  // Set mode: 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_RW_PIN 

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_us(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); 

delay_us(1); 

    

return(retval);    

}    

#endif 

//--------------------------------------- 

// Read a byte from the LCD and return it. 

#ifdef USE_RW_PIN 

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_RW_PIN 

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_RW_PIN 

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; 

   lcd_line = 1; 

   output_low(LCD_RS); 

   #ifdef USE_RW_PIN 

      output_low(LCD_RW); 

   #endif 

   output_low(LCD_E); 

   // Some LCDs require 15 ms minimum delay after 

   // power-up.  Others require 30 ms.  I'm going 

   // to set it to 35 ms, so it should work with 

   // all of them. 

   delay_ms(35);          

   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 50 us, so in 

      // that case, lets just do a 5 ms delay 

      // after all four of them. 

      #ifndef USE_RW_PIN 

         delay_ms(5); 

      #endif 

   } 

} 

//---------------------------- 

void lcd_gotoxy(int8 x, int8 y) 

{ 

int8 address; 

switch(y) 

  { 

   case 1: 

     address = LCD_LINE_1_ADDRESS; 

     break; 

   case 2: 

     address = LCD_LINE_2_ADDRESS; 

     break; 

   case 3: 

     address = LCD_LINE_3_ADDRESS; 

     break; 

   case 4: 

     address = LCD_LINE_4_ADDRESS; 

     break; 

   default: 

     address = LCD_LINE_1_ADDRESS; 

     break; 

      

  } 

address += x-1; 

lcd_send_byte(0, 0x80 | address); 

} 

//----------------------------- 

void lcd_putc(char c) 

{ 

 switch(c) 

   { 

    case '\f': 

      lcd_send_byte(0,1); 

      lcd_line = 1; 

      delay_ms(2); 

      break; 

    

    case '\n': 

       lcd_gotoxy(1, ++lcd_line); 

       break; 

    

    case '\b': 

       lcd_send_byte(0,0x10); 

       break; 

    

    default: 

       lcd_send_byte(1,c); 

       break; 

   } 

} 

//------------------------------ 

#ifdef USE_RW_PIN 

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 

ให้เพื่อนทดสอบ ลองเปลี่ยนขาที่ต่อกับ LCD โดยแก้ไขโค๊ดใน Flex_LCD420.c ในที่นี้ผมลองแก้คอมเม้นต์ออก เพิ่อทดสอบการย้ายขาไมโคร ว่าจะต่อได้หมดทุกขาไหม โดยแก้ไขเป็น

#define LCD_DB4   PIN_D4 

#define LCD_DB5   PIN_B1 

#define LCD_DB6   PIN_C5 

#define LCD_DB7   PIN_B5 

#define LCD_RS    PIN_E2 

#define LCD_RW    PIN_B2 

#define LCD_E     PIN_D6 

่ผลทดลอง 

#include <16f877a.h>

#fuses HS,NOWDT,NOLVP,NOBROWNOUT

#use delay(clock=20M)

#include "Flex_LCD420.c"

void main(void)

{

    lcd_init();

    delay_ms(200);

    while(TRUE)

    {

      lcd_gotoxy(1,1);

      lcd_putc("Hello World");

      lcd_gotoxy(1,2);

      lcd_putc("Test mix port");      

    }

}

เครดิต : PCM programmer

http://www.ccsinfo.com/forum/viewtopic.php?t=28268