test_i2cmaster.c

/****************************************************************************
Title:    Access serial EEPROM 24C02 using I2C interace
Author:   Peter Fleury <pfleury@gmx.ch>
File:     $Id: test_i2cmaster.c,v 1.3 2015/09/16 09:29:24 peter Exp $
Software: AVR-GCC 4.x
Hardware: any AVR device can be used when using i2cmaster.S or any
          AVR device with hardware TWI interface when using twimaster.c

Description:
    This example shows how the I2C/TWI library i2cmaster.S or twimaster.c 
	can be used to access a serial eeprom.
 
*****************************************************************************/
#include <avr/io.h>
#include "i2cmaster.h"


#define Dev24C02  0xA2      // device address of EEPROM 24C02, see datasheet


int main(void)
{
    unsigned char ret;
    

    DDRB  = 0xff;                              // use all pins on port B for output 
    PORTB = 0xff;                              // (active low LED's )

    i2c_init();                                // init I2C interface

    /* write 0x75 to eeprom address 0x05 (Byte Write) */
    ret = i2c_start(Dev24C02+I2C_WRITE);       // set device address and write mode
    if ( ret ) {
        /* failed to issue start condition, possibly no device found */
        i2c_stop();
        PORTB=0x00;                            // activate all 8 LED to show error */
    }else {
        /* issuing start condition ok, device accessible */
        i2c_write(0x05);                       // write address = 5
        i2c_write(0x75);                       // ret=0 -> Ok, ret=1 -> no ACK 
        i2c_stop();                            // set stop conditon = release bus

        /* write ok, read value back from eeprom address 0x05, wait until 
           the device is no longer busy from the previous write operation */
        i2c_start_wait(Dev24C02+I2C_WRITE);     // set device address and write mode
        i2c_write(0x05);                        // write address = 5
        i2c_rep_start(Dev24C02+I2C_READ);       // set device address and read mode
        ret = i2c_readNak();                    // read one byte
        i2c_stop();
        
        PORTB = ~ret;                           // output byte on the LED's

        /* write 0x70,0x71,072,073 to eeprom address 0x00..0x03 (Page Write),
           wait until the device is no longer busy from the previous write operation */
        i2c_start_wait(Dev24C02+I2C_WRITE);     // set device address and write mode
        i2c_write(0x00);                        // write start address = 0
        i2c_write(0x70);                        // write data to address 0
        i2c_write(0x71);                        //    "    "   "    "    1
        i2c_write(0x72);                        //    "    "   "    "    2
        i2c_write(0x74);                        //    "    "   "    "    3
        i2c_stop();                             // set stop conditon = release bus
    
        /* write ok, read value back from eeprom address 0..3 (Sequencial Read),
           wait until the device is no longer busy from the previous write operation */
        i2c_start_wait(Dev24C02+I2C_WRITE);      // set device address and write mode
        i2c_write(0x00);                         // write address = 0
        i2c_rep_start(Dev24C02+I2C_READ);        // set device address and read mode
        ret = i2c_readAck();                       // read one byte form address 0
        ret = i2c_readAck();                       //  "    "    "    "     "    1
        ret = i2c_readAck();                       //  "    "    "    "     "    2
        ret = i2c_readNak();                       //  "    "    "    "     "    3
        i2c_stop();                              // set stop condition = release bus
    
        PORTB = ~ret;                            // output byte on the LED's        
    }
    
    for(;;);	
}