flash_module.c

PIC_Hi-Tech_C_Mike_Pearces_I2C_routines Microchi PIC_Hi-Tech C_I2C_for_EEPROM_24LC01B Code

//read/write flash memory. 
// Uses HITECH macro for flash erase

//prototypes
unsigned char flash_readbyte(long addr);
long flash_readstr(char *s, long addr, unsigned char max);
void do_flash_erase(long addr);
char flash_writebuf(long addr, char *buf);



unsigned char flash_readbyte(long addr){
#if defined(HI_TECH_C)
  TBLPTR = (far unsigned char *)addr;	
#endif
#if defined(__18CXX)
  TBLPTR = (unsigned short long)addr;	
#endif
  TBLRDPOSTINC(); //asm("TBLRD*+");
  return((unsigned char)TABLAT);
}

long flash_readstr(char *s, long addr, unsigned char max){
  unsigned char c,cnt;

  cnt = 0;
  do {
    c = flash_readbyte(addr);
    addr++;
    *s = c;
    s++; cnt++;
  }while((c) && (cnt < (max-1)));
  // last byte non-zero, terminate this string
  if (c) *s = 0;
  return(addr);
}


void do_flash_erase(long addr){
  char istat;
#if defined(HI_TECH_C)
  TBLPTR = (far unsigned char *)addr;	
#endif
#if defined(__18CXX)
 TBLPTR = (unsigned short long)addr;	
#endif
  EEPGD=1;FREE=1;WREN=1;CFGS=0;
  istat = GIE; GIE = 0;
  EECON2 = 0x55; EECON2 = 0xAA;
  WR = 1; // CPU stalls
  NOP();   // asm("nop")
  GIE = istat; FREE=0;WREN=0;
}

// write 64 bytes , assumes 'addr' is on 64 byte boundary!
char flash_writebuf(long addr, char *buf){
  char i, j,istat, *s;

  do_flash_erase(addr);
  // before write, decrement address
  addr--;
#if defined(HI_TECH_C)
  TBLPTR = (far unsigned char *)addr;	
#endif
#if defined(__18CXX)
 TBLPTR = (unsigned short long)addr;	
#endif  	
  i = 0; j= 0;  s = buf;
  while (i < 64) {
    TABLAT=*s;
    TBLWTPREINC();  //asm("TBLWT+*");
    j++;i++;s++;
    if (j == 8) {
      // 8 bytes written to internal buff, do write
      EEPGD=1;FREE=0;WREN=1;CFGS=0;
      istat = GIE;
      GIE = 0;
      EECON2 = 0x55; EECON2 = 0xAA;
      WR = 1; // CPU stalls
      NOP();          //asm("NOP");
      GIE = istat;
      WREN = 0;
      j = 0;
    }
  }
  // verify contents written correctly
  i = 0;s = buf;
  addr++;  // get back to start
  while(i < 64) {
    j = flash_readbyte(addr);
    if (j != *s) return(1);
    i++;s++;addr++;
  }
  return(0);
}