Re: [avr-gcc-list] read write eeprom WINAVR20050214

[Dave Hansen]

From: "Royce & Sharal Pereira" <address@hidden>

> Hi,
> ----------------------------------------
> On Fri, 18 Feb 2005 10:57:53 +0700, andi  
> <address@hidden> wrote:
>
> > Hi,
> > I only got command read and write 1 byte eeprom for 255 byte eeprom size  
> > in eeprom.h.
> >
> > extern uint8_t eeprom_read_byte (const uint8_t *addr);
> >
> > extern void eeprom_write_byte (uint8_t *addr, uint8_t val);
> >
> > it's only for eeprom in address lower than 256 byte
> ------------------------------------------
> Actually that's right...I looked in avrlibc docs & I could not find

Actually, that's wrong.

> a  macro for writing a byte to a 16 bit eeprom address.
>
> Though you can write a byte to an 8 bit addr, and a word to a 16 bit addr.
>
> Or does this feature exist somewhere?

You're getting yourself wrapped around the axle.  The library defines the 
following (cut and pasted from the docs):

  uint8_t       eeprom_read_byte (const uint8_t *addr)
  uint16_t      eeprom_read_word (const uint16_t *addr)
  void  eeprom_read_block (void *buf, const void *addr, size_t n)
  void  eeprom_write_byte (uint8_t *addr, uint8_t val)
  void  eeprom_write_word (uint16_t *addr, uint16_t val)
  void  eeprom_write_block (const void *buf, void *addr, size_t n)

note that eeprom_read_byte and eeprom_write_byte take (const uint8_t *).  
This is a _pointer_ to a byte, not an 8-bit value.  Pointers are 16 bits 
wide.

Regards,
  -=Dave