display.cpp

//=====[Libraries]=============================================================

#include "mbed.h"
#include "arm_book_lib.h"
#include "display.h"

//=====[Declaration of private defines]========================================

#define DISPLAY_IR_CLEAR_DISPLAY   0b00000001
#define DISPLAY_IR_ENTRY_MODE_SET  0b00000100
#define DISPLAY_IR_DISPLAY_CONTROL 0b00001000
#define DISPLAY_IR_FUNCTION_SET    0b00100000
#define DISPLAY_IR_SET_DDRAM_ADDR  0b10000000

#define DISPLAY_IR_ENTRY_MODE_SET_INCREMENT 0b00000010
#define DISPLAY_IR_ENTRY_MODE_SET_DECREMENT 0b00000000
#define DISPLAY_IR_ENTRY_MODE_SET_SHIFT     0b00000001
#define DISPLAY_IR_ENTRY_MODE_SET_NO_SHIFT  0b00000000

#define DISPLAY_IR_DISPLAY_CONTROL_DISPLAY_ON  0b00000100
#define DISPLAY_IR_DISPLAY_CONTROL_DISPLAY_OFF 0b00000000
#define DISPLAY_IR_DISPLAY_CONTROL_CURSOR_ON   0b00000010
#define DISPLAY_IR_DISPLAY_CONTROL_CURSOR_OFF  0b00000000
#define DISPLAY_IR_DISPLAY_CONTROL_BLINK_ON    0b00000001
#define DISPLAY_IR_DISPLAY_CONTROL_BLINK_OFF   0b00000000

#define DISPLAY_IR_FUNCTION_SET_8BITS    0b00010000
#define DISPLAY_IR_FUNCTION_SET_4BITS    0b00000000
#define DISPLAY_IR_FUNCTION_SET_2LINES   0b00001000
#define DISPLAY_IR_FUNCTION_SET_1LINE    0b00000000
#define DISPLAY_IR_FUNCTION_SET_5x10DOTS 0b00000100
#define DISPLAY_IR_FUNCTION_SET_5x8DOTS  0b00000000

#define DISPLAY_20x4_LINE1_FIRST_CHARACTER_ADDRESS 0
#define DISPLAY_20x4_LINE2_FIRST_CHARACTER_ADDRESS 64
#define DISPLAY_20x4_LINE3_FIRST_CHARACTER_ADDRESS 20
#define DISPLAY_20x4_LINE4_FIRST_CHARACTER_ADDRESS 84

#define DISPLAY_RS_INSTRUCTION 0
#define DISPLAY_RS_DATA        1

#define DISPLAY_RW_WRITE 0
#define DISPLAY_RW_READ  1

#define DISPLAY_PIN_RS  4
#define DISPLAY_PIN_RW  5
#define DISPLAY_PIN_EN  6
#define DISPLAY_PIN_D0  7  
#define DISPLAY_PIN_D1  8  
#define DISPLAY_PIN_D2  9  
#define DISPLAY_PIN_D3 10
#define DISPLAY_PIN_D4 11
#define DISPLAY_PIN_D5 12 
#define DISPLAY_PIN_D6 13 
#define DISPLAY_PIN_D7 14 

//=====[Declaration of private data types]=====================================

//=====[Declaration and initialization of public global objects]===============

DigitalOut displayD4( D4 );
DigitalOut displayD5( D5 );
DigitalOut displayD6( D6 );
DigitalOut displayD7( D7 );
DigitalOut displayRs( D8 );
DigitalOut displayEn( D9 );

//=====[Declaration of external public global variables]=======================

//=====[Declaration and initialization of public global variables]=============

//=====[Declaration and initialization of private global variables]============

static display_t display;
static bool initial8BitCommunicationIsCompleted;

//=====[Declarations (prototypes) of private functions]========================

static void displayPinWrite( uint8_t pinName, int value );
static void displayDataBusWrite( uint8_t dataByte );
static void displayCodeWrite( bool type, uint8_t dataBus );

//=====[Implementations of public functions]===================================

void displayInit( displayConnection_t connection )
{
    display.connection = connection;
    
    initial8BitCommunicationIsCompleted = false;    

    delay( 50 );
    
    displayCodeWrite( DISPLAY_RS_INSTRUCTION, 
                      DISPLAY_IR_FUNCTION_SET | 
                      DISPLAY_IR_FUNCTION_SET_8BITS );
    delay( 5 );
            
    displayCodeWrite( DISPLAY_RS_INSTRUCTION, 
                      DISPLAY_IR_FUNCTION_SET | 
                      DISPLAY_IR_FUNCTION_SET_8BITS );
    delay( 1 ); 

    displayCodeWrite( DISPLAY_RS_INSTRUCTION, 
                      DISPLAY_IR_FUNCTION_SET | 
                      DISPLAY_IR_FUNCTION_SET_8BITS );
    delay( 1 );  

    switch( display.connection ) {
        case DISPLAY_CONNECTION_GPIO_8BITS:
            displayCodeWrite( DISPLAY_RS_INSTRUCTION, 
                              DISPLAY_IR_FUNCTION_SET | 
                              DISPLAY_IR_FUNCTION_SET_8BITS | 
                              DISPLAY_IR_FUNCTION_SET_2LINES |
                              DISPLAY_IR_FUNCTION_SET_5x8DOTS );
            delay( 1 );         
        break;
        
        case DISPLAY_CONNECTION_GPIO_4BITS:
            displayCodeWrite( DISPLAY_RS_INSTRUCTION, 
                              DISPLAY_IR_FUNCTION_SET | 
                              DISPLAY_IR_FUNCTION_SET_4BITS );
            delay( 1 );  

            initial8BitCommunicationIsCompleted = true;  

            displayCodeWrite( DISPLAY_RS_INSTRUCTION, 
                              DISPLAY_IR_FUNCTION_SET | 
                              DISPLAY_IR_FUNCTION_SET_4BITS | 
                              DISPLAY_IR_FUNCTION_SET_2LINES |
                              DISPLAY_IR_FUNCTION_SET_5x8DOTS );
            delay( 1 );                                      
        break;
    }

    displayCodeWrite( DISPLAY_RS_INSTRUCTION, 
                      DISPLAY_IR_DISPLAY_CONTROL |
                      DISPLAY_IR_DISPLAY_CONTROL_DISPLAY_OFF |      
                      DISPLAY_IR_DISPLAY_CONTROL_CURSOR_OFF |       
                      DISPLAY_IR_DISPLAY_CONTROL_BLINK_OFF );       
    delay( 1 );          

    displayCodeWrite( DISPLAY_RS_INSTRUCTION, 
                      DISPLAY_IR_CLEAR_DISPLAY );       
    delay( 1 ); 

    displayCodeWrite( DISPLAY_RS_INSTRUCTION, 
                      DISPLAY_IR_ENTRY_MODE_SET |
                      DISPLAY_IR_ENTRY_MODE_SET_INCREMENT |       
                      DISPLAY_IR_ENTRY_MODE_SET_NO_SHIFT );                  
    delay( 1 );           

    displayCodeWrite( DISPLAY_RS_INSTRUCTION, 
                      DISPLAY_IR_DISPLAY_CONTROL |
                      DISPLAY_IR_DISPLAY_CONTROL_DISPLAY_ON |      
                      DISPLAY_IR_DISPLAY_CONTROL_CURSOR_OFF |    
                      DISPLAY_IR_DISPLAY_CONTROL_BLINK_OFF );    
    delay( 1 );  
}

void displayCharPositionWrite( uint8_t charPositionX, uint8_t charPositionY )
{    
    switch( charPositionY ) {
        case 0:
            displayCodeWrite( DISPLAY_RS_INSTRUCTION, 
                              DISPLAY_IR_SET_DDRAM_ADDR |
                              ( DISPLAY_20x4_LINE1_FIRST_CHARACTER_ADDRESS +
                                charPositionX ) );
            delay( 1 );         
        break;
       
        case 1:
            displayCodeWrite( DISPLAY_RS_INSTRUCTION, 
                              DISPLAY_IR_SET_DDRAM_ADDR |
                              ( DISPLAY_20x4_LINE2_FIRST_CHARACTER_ADDRESS +
                                charPositionX ) );
            delay( 1 );         
        break;
       
        case 2:
            displayCodeWrite( DISPLAY_RS_INSTRUCTION, 
                              DISPLAY_IR_SET_DDRAM_ADDR |
                              ( DISPLAY_20x4_LINE3_FIRST_CHARACTER_ADDRESS +
                                charPositionX ) );
            delay( 1 );         
        break;

        case 3:
            displayCodeWrite( DISPLAY_RS_INSTRUCTION, 
                              DISPLAY_IR_SET_DDRAM_ADDR |
                              ( DISPLAY_20x4_LINE4_FIRST_CHARACTER_ADDRESS +
                                charPositionX ) );
            delay( 1 );         
        break;
    }
}


void displayStringWrite( const char * str )
{
    while (*str) {
        displayCodeWrite(DISPLAY_RS_DATA, *str++);
    }
}

//=====[Implementations of private functions]==================================

static void displayCodeWrite( bool type, uint8_t dataBus )
{
    if ( type == DISPLAY_RS_INSTRUCTION )
        displayPinWrite( DISPLAY_PIN_RS, DISPLAY_RS_INSTRUCTION);
        else
        displayPinWrite( DISPLAY_PIN_RS, DISPLAY_RS_DATA);
    displayPinWrite( DISPLAY_PIN_RW, DISPLAY_RW_WRITE );
    displayDataBusWrite( dataBus );
}

static void displayPinWrite( uint8_t pinName, int value )
{
    switch( display.connection ) {
        case DISPLAY_CONNECTION_GPIO_8BITS:
            switch( pinName ) {
                case DISPLAY_PIN_D4: displayD4 = value;   break;
                case DISPLAY_PIN_D5: displayD5 = value;   break;
                case DISPLAY_PIN_D6: displayD6 = value;   break;
                case DISPLAY_PIN_D7: displayD7 = value;   break;
                case DISPLAY_PIN_RS: displayRs = value;   break;
                case DISPLAY_PIN_EN: displayEn = value;   break;
                case DISPLAY_PIN_RW: break; 
                default: break;
            }
            break;
        case DISPLAY_CONNECTION_GPIO_4BITS:
            switch( pinName ) {
                case DISPLAY_PIN_D4: displayD4 = value;   break;
                case DISPLAY_PIN_D5: displayD5 = value;   break;
                case DISPLAY_PIN_D6: displayD6 = value;   break;
                case DISPLAY_PIN_D7: displayD7 = value;   break;
                case DISPLAY_PIN_RS: displayRs = value;   break;
                case DISPLAY_PIN_EN: displayEn = value;   break;
                case DISPLAY_PIN_RW: break; 
                default: break;
            }
            break;
    }
}

static void displayDataBusWrite( uint8_t dataBus )
{
    displayPinWrite( DISPLAY_PIN_EN, OFF );
    displayPinWrite( DISPLAY_PIN_D7, dataBus & 0b10000000 );
    displayPinWrite( DISPLAY_PIN_D6, dataBus & 0b01000000 );
    displayPinWrite( DISPLAY_PIN_D5, dataBus & 0b00100000 );
    displayPinWrite( DISPLAY_PIN_D4, dataBus & 0b00010000 );
    switch( display.connection ) {
        case DISPLAY_CONNECTION_GPIO_8BITS:
            displayPinWrite( DISPLAY_PIN_D3, dataBus & 0b00001000 );
            displayPinWrite( DISPLAY_PIN_D2, dataBus & 0b00000100 );  
            displayPinWrite( DISPLAY_PIN_D1, dataBus & 0b00000010 );      
            displayPinWrite( DISPLAY_PIN_D0, dataBus & 0b00000001 );
        break; 
              
        case DISPLAY_CONNECTION_GPIO_4BITS:
            if ( initial8BitCommunicationIsCompleted == true) {
                displayPinWrite( DISPLAY_PIN_EN, ON );         
                delay( 1 );
                displayPinWrite( DISPLAY_PIN_EN, OFF );              
                delay( 1 );        
                displayPinWrite( DISPLAY_PIN_D7, dataBus & 0b00001000 );
                displayPinWrite( DISPLAY_PIN_D6, dataBus & 0b00000100 );  
                displayPinWrite( DISPLAY_PIN_D5, dataBus & 0b00000010 );      
                displayPinWrite( DISPLAY_PIN_D4, dataBus & 0b00000001 );                
            }
        break;
    
    }
    displayPinWrite( DISPLAY_PIN_EN, ON );              
    delay( 1 );
    displayPinWrite( DISPLAY_PIN_EN, OFF );  
    delay( 1 );                   
}