Thema: EEPROM lesen/schreiben

Nun lese ich aber etwas von eeprom_read_byte auf microcontroller.net.

Das bezieht sich auf den EEPROM im Kontroller.
Die Device-Adresse sollte A8 sein?
Vielleicht kannst du mit dem hier was anfangen:

Code:

/****************************************************************************
Title:    Access serial EEPROM 24C02 using I2C interace
Author:   Peter Fleury <pfleury@gmx.ch> http://jump.to/fleury
Date:     9-Mar-2003
Software: AVR-GCC 3.3
Hardware: AT90S8515 at 4 Mhz, any AVR device can be used

Description:
    This example shows how the I2C library i2cmaster.S can be used to 
    access a serial eeprom.
    Based on Atmel Application Note AVR300, adapted to AVR-GCC C interface

*****************************************************************************/
#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(;;);	
}

Bezieht sich zwar auf einen 24C02 sollte aber sonst passen.

Der 28C08 hat nur ein E2, mit A1 und A2 schaltest du zwischen den Blöcken um.
Das 1010 ist in hex ein A, daher A8.

Zitat von uwegw

Der einzige Grund für ein externes EEPROM wäre, dass man mehr Speicher braucht als intern vorhanden ist.

Nicht nur. Weiterer Vorteil: Ext. EEPROM ist austauschbar, sollte man den mal kaputtschreiben. Aber da wärs mal interessant: Wer hat schon mal den internen EEPROM im normalen Betrieb zerlegt?