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    F - Cpu: #Define #Include #Include #Include

    Uploaded by

    Phenias Manyasha
    This document contains code for initializing an I2C interface and LCD display module. It defines functions for initializing the I2C bus, sending/receiving data, and controlling the LCD. These include functions for initializing the LCD, clearing its display, writing data and commands to it, and writing strings to its display. The main function initializes everything and writes an example string to the LCD in a loop.

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    © All Rights Reserved
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    F - Cpu: #Define #Include #Include #Include

    Uploaded by

    Phenias Manyasha
    106 views8 pages
    This document contains code for initializing an I2C interface and LCD display module. It defines functions for initializing the I2C bus, sending/receiving data, and controlling the LCD. These include functions for initializing the LCD, clearing its display, writing data and commands to it, and writing strings to its display. The main function initializes everything and writes an example string to the LCD in a loop.

    Original Description:

    Original Title

    I2C

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    This document contains code for initializing an I2C interface and LCD display module. It defines functions for initializing the I2C bus, sending/receiving data, and controlling the LCD. These include functions for initializing the LCD, clearing its display, writing data and commands to it, and writing strings to its display. The main function initializes everything and writes an example string to the LCD in a loop.

    Copyright:

    © All Rights Reserved
    Download as DOC, PDF, TXT or read online from Scribd
    Download as doc, pdf, or txt
    106 views8 pages

    F - Cpu: #Define #Include #Include #Include

    Uploaded by

    Phenias Manyasha
    This document contains code for initializing an I2C interface and LCD display module. It defines functions for initializing the I2C bus, sending/receiving data, and controlling the LCD. These include functions for initializing the LCD, clearing its display, writing data and commands to it, and writing strings to its display. The main function initializes everything and writes an example string to the LCD in a loop.

    Copyright:

    © All Rights Reserved
    Download as DOC, PDF, TXT or read online from Scribd
    Download as doc, pdf, or txt
    of 8

    #define F_CPU 8000000

    #include <avr/io.h>
    #include <util/delay.h>
    #include <avr/pgmspace.h>

    /* Pin assignment for control lines on the PCF8574 */


    #define RS 0x10
    #define RW 0x20
    #define EN 0x40
    #define BL 0x80
    #define START 0x08 // START has been transmitted
    #define REP_START 0x10 // Repeated START has been transmitted
    #define MTX_ADR_ACK 0x18 // SLA+W has been transmitted and ACK received
    #define MTX_DATA_ACK 0x28 // Data byte has been transmitted and ACK
    received
    #define SUCCESS 0xFF // return code for success
    #define LCD_FUNCTION_4BIT_1LINE 0x20 /* 4-bit interface, single line, 5x7 dots */
    #define LCD_FUNCTION_4BIT_2LINES 0x28 /* 4-bit interface, dual line, 5x7 dots */
    #define LCD_FUNCTION_8BIT_1LINE 0x30 /* 8-bit interface, single line, 5x7 dots */
    #define LCD_FUNCTION_8BIT_2LINES 0x38 /* 8-bit interface, dual line, 5x7 dots */
    #define LCD_DISP_ON 0x0C /* display on, cursor off */
    #define LCD_CLR 0 /* DB0: clear display */

    #define PCF8574_ADDR 0x40 // Slave address of PCF8574


    #define SCL_CLOCK 10 // Set SCL to 100 KHz at 3.6 MHz xtal
    // See application note AVR315, table 1

    //#define delay(us) _delayFourCycles( ( ( 1*(F_CPU/4000) )*us)/1000 )

    /*************************************************************************
    Sends one byte to the display using I2C bus.
    Input: data = byte to be sent, df = flag if data (1) or command (0)
    Returns: none
    *************************************************************************/
    void Wait_TWI_int(void)
    {
    while (!(TWCR & (1<<TWINT))) // Wait for TWI interrupt flag set
    ;
    }

    /****************************************************************************
    Public functions
    ****************************************************************************/

    void i2c_init(void)
    {
    TWBR = SCL_CLOCK; // Set SCL frequency
    TWCR = (1<<TWEN);
    }

    unsigned char i2c_write(unsigned char data)


    {
    Wait_TWI_int();

    TWDR = data;
    TWCR = ((1<<TWINT)+(1<<TWEN)); // Clear int flag to send byte

    Wait_TWI_int();
    if(TWSR != MTX_DATA_ACK) // If NACK received return TWSR
    return TWSR;
    return SUCCESS;
    }

    unsigned char i2c_send_start(void)


    {
    TWCR = ((1<<TWINT)+(1<<TWSTA)+(1<<TWEN));// Send START

    Wait_TWI_int();

    if((TWSR != START)&&(TWSR != REP_START))// If status other than START


    return TWSR; // transmitted (0x08) or Repeated
    return SUCCESS; // START transmitted (0x10)
    // -> error and return TWSR.
    // If success return SUCCESS.
    }

    void i2c_send_stop(void)
    {
    TWCR = ((1<<TWEN)+(1<<TWINT)+(1<<TWSTO));// Send STOP condition
    }

    unsigned char i2c_send_adr(unsigned char adr)


    {
    Wait_TWI_int();

    TWDR = adr;
    TWCR = ((1<<TWINT)+(1<<TWEN)); // Clear int flag to send byte

    Wait_TWI_int();

    if (TWSR != MTX_ADR_ACK) // If NACK received return TWSR


    return TWSR;
    return SUCCESS; // Else return SUCCESS
    }

    static void
    lcd_write(unsigned char data, unsigned char df)
    {
    unsigned char dataBits;

    i2c_send_start();
    i2c_send_adr(PCF8574_ADDR);

    dataBits = (data >> 4) & 0x0f; // Output high nibble


    if (df)
    dataBits |= RS;
    if (!OCR1A)
    dataBits |= BL;
    i2c_write(dataBits);
    i2c_write(EN | dataBits);
    i2c_write(dataBits);

    dataBits = data & 0x0f; // Output low nibble


    if (df)
    dataBits |= RS;
    if (!OCR1A)
    dataBits |= BL;
    i2c_write(dataBits);
    i2c_write(EN | dataBits);
    i2c_write(dataBits);
    i2c_send_stop();
    _delay_ms(40); // Minimum execution time
    }

    /*
    * PUBLIC FUNCTIONS
    */

    /*************************************************************************
    Send LCD controller instruction command
    Input: instruction to send to LCD controller, see HD44780 data sheet
    Returns: none
    *************************************************************************/
    void lcd_command(unsigned char cmd)
    {
    lcd_write(cmd, 0);
    }

    /*************************************************************************
    Send data byte to LCD controller
    Input: data to send to LCD controller, see HD44780 data sheet
    Returns: none
    *************************************************************************/
    void lcd_data(unsigned char data)
    {
    lcd_write(data, 1);
    }

    /*************************************************************************
    Clear display
    *************************************************************************/
    void lcd_clrscr(void)
    {
    lcd_command(1<<LCD_CLR);
    _delay_ms(1500);
    }

    /*************************************************************************
    Display string without auto linefeed
    Input: string to be displayed
    Returns: none
    *************************************************************************/
    void lcd_puts(const char *s)
    {
    while ( (*s) )
    lcd_data(*s++);
    }

    /*************************************************************************
    Display string from program memory without auto linefeed
    Input: string from program memory be be displayed
    Returns: none
    *************************************************************************/
    void lcd_puts_p(const char *progmem_s)
    {
    register char c;

    while ( (c = pgm_read_byte(progmem_s++)) ) {
    lcd_data(c);
    }
    }
    /*************************************************************************
    Initialize I2C and display
    *************************************************************************/
    void lcd_init(void)
    {
    i2c_init();

    _delay_ms(16000); /* wait 16ms or more after power-on */

    i2c_send_start();
    i2c_send_adr(PCF8574_ADDR);

    /*
    * Send 0x03 a couple of times which is the same as
    * ((1<<LCD_FUNCTION | 1<<LCD_FUNCTION_8BIT) >> 4)
    */
    i2c_write(0x03);
    i2c_write(EN | 0x03);
    i2c_write(0x03);
    _delay_ms(4992);
    i2c_write(EN | 0x03);
    i2c_write(0x03);
    _delay_ms(64);
    i2c_write(EN | 0x03);
    i2c_write(0x03);
    _delay_ms(64);
    i2c_write(0x02); /* Switch to 4 bit mode */
    i2c_write(EN | 0x02);
    i2c_write(0x02);

    i2c_send_stop();

    lcd_command(LCD_FUNCTION_4BIT_2LINES); /* function set: display lines */


    lcd_command(LCD_DISP_ON); /* Display on, Cursor on, Blink off */
    lcd_clrscr();
    }
    int main(void)
    {
    //PORTMUX.CTRLB = PORTMUX_TWI0_ALTERNATE_gc; // PA1, PA2 are alternate pins
    for SCL and SDA, so need to use the PORTMUX register bit to enable

    DDRB=0XFF;
    DDRC=0XFF;

    while(1) //continue
    {
    lcd_init();
    _delay_ms(2);
    lcd_puts_p("text1");

    }
    }
    #define F_CPU 8000000UL
    #define get_bit(reg,bitnum) ((reg & (1<<bitnum))>>bitnum) // get bit macro used to get
    the value of a certain bit.
    #include <avr/io.h>
    #include <util/delay.h>

    void TWI_Init (void)


    {
    //set_bit(TWCR,6);
    TWSR=0;
    TWBR=0x07;
    TWCR|=(1<<TWEN);

    void TWI_Start (void)

    TWCR= (1<<TWINT)|(1<<TWSTA)|(1<<TWEN);

    while (get_bit(TWCR,TWINT)==0)

    void TWI_Stop (void)

    TWCR=(1<<TWSTO)|(1<<TWEN)|(1<<TWINT);

    void TWI_Write (char data)

    TWDR=data;

    TWCR= (1<<TWINT)|(1<<TWEN);

    while (get_bit(TWCR,TWINT)==0)

    }
    void TWI_Read_Nack (char* ptr) // The function argument is a pointer to a memory place
    in the MCU to store the received data in

    TWCR=(1<<TWINT)|(1<<TWEN);

    while (get_bit(TWCR,TWINT)==0)

    *ptr=TWDR;

    void EEPROM_Write (char data, char address)

    TWI_Start();

    TWI_Write(0xA8); //slave address is 1010.100 and a 0 in the 8th bit to indicate


    Writting.

    TWI_Write(address);

    TWI_Write(data);

    TWI_Stop();

    void EEPROM_Read (char address, char* ptr) // the function arguments are an address in
    the EEPROM to read from and a pointer to a memory place in the MCU to store the read
    data in

    TWI_Start();

    TWI_Write(0xA8);

    TWI_Write(address);

    TWI_Start();

    TWI_Write(0xA9);

    TWI_Read_Nack(ptr);

    TWI_Stop();
    }

    int main(void)

    char R;

    DDRD=0b11111111;

    TWI_Init();

    while(1)

    EEPROM_Write(0xE0,0x00);

    _delay_ms(1000); // You must allow suffcent delay for the EEPROM to


    complete the its internal write cycle

    EEPROM_Read(0x00,&R);

    if (R==0xE0)

    PORTD=0b01000000;

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