Buscando por la red (DIOS MIO SI QUE ES GRANDE) encontre un ejemplo de lectura y escritura de la eprom interna del PIC con un 18F
aqui va:
// read and write eeprom of PIC18F2550 (and 18F2455, 18F4455, 18F4550)
// EEPROM size is 256 bytes
// (c) Raphael Wimmer. Licensed under GNU GPL v2 or higher
#include <pic18fregs.h>
#include <stdio.h>
#include <usart.h>
#pragma stack 0x300 0xff // set 64 byte stack at 0x300, needed by sdcc
void ee_write_byte(unsigned char address, unsigned char *_data){
EEDATA = *_data;
EEADR = address;
// start write sequence as described in datasheet, page 91
EECON1bits.EEPGD = 0;
EECON1bits.CFGS = 0;
EECON1bits.WREN = 1; // enable writes to data EEPROM
INTCONbits.GIE = 0; // disable interrupts
EECON2 = 0x55;
EECON2 = 0x0AA;
EECON1bits.WR = 1; // start writing
while(EECON1bits.WR){
_asm nop _endasm;}
if(EECON1bits.WRERR){
printf("ERROR: writing to EEPROM failed!\n");
}
EECON1bits.WREN = 0;
INTCONbits.GIE = 1; // enable interrupts
}
void ee_read_byte(unsigned char address, unsigned char *_data){
EEADR = address;
EECON1bits.CFGS = 0;
EECON1bits.EEPGD = 0;
EECON1bits.RD = 1;
*_data = EEDATA;
}
void initUsart()
{
usart_open( // Use USART library to initialise the hardware
USART_TX_INT_OFF
& USART_RX_INT_OFF
& USART_BRGH_HIGH
& USART_ASYNCH_MODE
& USART_EIGHT_BIT,
10 // '10' = 115200 Baud with 20 MHz oscillator and BRGH=1
);
stdout = STREAM_USART;
}
// very simple example. use on an erased eeprom
void main(){
char save_me = 'x';
char from_eeprom;
initUsart();
printf("EEPROM-Demo\n");
ee_read_byte(0x00, &from_eeprom);
printf("Char read from 0x00: %c\n", from_eeprom);
ee_write_byte(0x00, &save_me);
printf("Char written to 0x00: %c\n", save_me);
ee_read_byte(0x00, &from_eeprom);
printf("Char read from 0x00: %c\n\n", from_eeprom);
}
Es facil de entender se puede dividir el programa para generar una libreria de lectura y escritura de eprom otra cosa que me parecio extrana es que el autor señala que este comando debe ir por defecto: #pragma stack 0x300 0xff // set 64 byte stack at 0x300, needed by sdcc aqui termina, el programa utiliza otra libreria de comunicasión serial que se encuentra en la carpeta de sdcc
saludos y suerte
