_256eeprom.c

avr的icc编译器的源代码

/* Modified for 2313 by Richard Man, ImageCraft */
/*
**	Purpose:    EEPROM read & write routines
**
**  Version:    1.0.0, 8:th of May 1999
**
**  Author:     Lars Wictorsson
**              LAWICEL / SWEDEN
**              http://www.lawicel.com   [e-mail]
**
**  History:    1999-05-08  Created
**/

#include <io2313v.h>	// or io4414.h, or...

int _256EEPROMwrite( int location, unsigned char byte)
{
	unsigned char oldSREG;
    while (EECR & 0x02);                // Wait until any earlier write is done

    EEAR = location & 0xFF;            // Set EEPROM address
    EEDR = byte;

	oldSREG = SREG;
	SREG &= ~0x80;		// interrupt off
    EECR |= 0x04;                       // Set MASTER WRITE enable
    EECR |= 0x02;                       // Set WRITE strobe

	SREG = oldSREG;

    return 0;                           // return Success.
                                        // Could be expanded so that
                                        // the routine checks that the address
                                        // is within the range of the chip.
}                   

unsigned char _256EEPROMread( int location)
{
    while (EECR & 0x02);                // Wait until any earlier write is done.
                                        // This is just a safety incase a write
                                        // was done and is not completed when
                                        // the read was called. If this test is
                                        // not done, the current write operation
                                        // will fail due to that the address or
                                        // data is changed.

    EEAR = location & 0xFF;            // Set EEPROM address
    
    EECR |= 0x01;                       // Set READ strobe
    
    return (EEDR);                      // Return byte
}