eeprom.cpp

/* 
  Beschreibung:     Byteweises Schreiben und Lesen von EEPROM
										24LCxx am i2c-Bus

  Autor:            Rolf Rahm
  Datum:            26.10.2017
  Letzte Änderung:  18.03.2018
*/
#include "controller.h"
#include "eeprom.h"

void eeprom_init(void)
{
  i2c_init();     // Zugriff auf EEPROM über i2C-Bus
}

uint8_t eeprom_read (uint8_t i2c_address, uint16_t address)
{
  volatile uint8_t temp;

  i2c_start();
  i2c_write(i2c_address);				// I2C-Adresse EEPROM1
  i2c_write((address>>8) & 0x00ff);	// Address High Byte schreiben
	i2c_write(address & 0x00ff);			// Address Low Byte schreiben
	
  i2c_start();								// Repeated Start
	i2c_write(i2c_address | 0x01);
  temp = i2c_read(NACK);
  i2c_stop();
  return temp;
}

void eeprom_write(uint8_t i2c_address, uint16_t address, uint8_t value)
{
	uint8_t	response;
	
  i2c_start();
  i2c_write(i2c_address);
  i2c_write((address>>8) & 0x00ff);				// EEPROM-Adresse High Byte schreiben
	i2c_write(address & 0x00ff);						// EEPROM-Adresse Low Byte schreiben
  
  i2c_write(value);	
  i2c_stop();
	delay_100us(1);													// Kurze Pause nötig!!
	response = NACK;
	do																			// Acknowledge-Polling bis Schreibvorgang
	{																				// beendet.
		i2c_start();
		response = i2c_write(i2c_address);
	} while (response == NACK);
	i2c_stop();
}
// testet den gewählten EEPROM durch wiederholtes
// schreiben und lesen von 0xaa und 0x55 auf jede 
// Speicherstelle bis zur Endadresse (eeprom.h)
// Der ursrüngliche Wert wird wieder hergestellt.
int8_t eeprom_memtest(uint8_t i2c_address)
{
	uint16_t adresse;
	uint8_t buf,temp;
	
	for(adresse = 0x0000;adresse <= EEPROM_END_ADDRESS;adresse++)
	{
		temp = eeprom_read(i2c_address,adresse);
		lcd_setcursor(2,1);
		lcd_int(adresse);
		lcd_print(" AA:");
		eeprom_write(i2c_address,adresse,0xAA);
		buf = eeprom_read(i2c_address,adresse);
		if (buf == 0xAA)
		{
			lcd_print("o");
		}
		else
		{
			lcd_print("x");
			return -1;
		}
		
		lcd_print(" 55:");
		eeprom_write(i2c_address,adresse,0x55);
		buf = eeprom_read(i2c_address,adresse);
		if (buf == 0x55)
		{
			lcd_print("o");
		}
		else
		{
			lcd_print("x");
			return -1;
		}
		eeprom_write(i2c_address,adresse,temp);
	}
  return 0;
}