Hi,
Sorry, num should be STRU_SIZE.
But that's not the error I'm getting, It's just a typo while pasting a
sample code here.
In my actual code I did use STRU_SIZE (not num).
On Wed, 10 Jun 2020 at 00:27, Dave Hansen <i...@hotmail.com> wrote:
> You wrote
> >>> eeprom_read_block((void *)&setPgm, (const void *)eepLoc, num) ;
>
> What is num?
>
> -=Dave
> ------------------------------
> *From:* AVR-GCC-list <avr-gcc-list-bounces+iddw=hotmail....@nongnu.org>
> on behalf of Royce Pereira <royc...@gmail.com>
> *Sent:* Tuesday, June 9, 2020 8:18 AM
> *To:* avr-gcc-list@nongnu.org <avr-gcc-list@nongnu.org>
> *Subject:* Saving & retreiving a structure in eeprom
>
> Hi,
>
> The MPU is ATMega8. AVR-GCC version is 9.1.0
> I have a structure that I'm trying to save (& retrieve in eeprom).
> Furthermore, it is to be saved in an indexed location in the eeprom from 0
> to 29.
> The structure is 4 bytes in size. So total 127 bytes are used in EEPROM
> //-----------------------------------------
> #define EEP_START 7 //offset in EEPROM where my structure storage
> starts.
>
> typedef struct
> {
> int temp ;
> unsigned int time ;
> } _pgm ;
>
> #define STRU_SIZE (sizeof(_pgm))
>
> _pgm setPgm ; //create struct in RAM.
> uint16_t eepLoc ; //holds address of EEPROM
> uint8_t index ; //index to read from in EEPROM...
> //----------------------------------------------------------
> //save struct from RAM to an indexed location in EEPROM...
> void savPgm(char idx)
> {
> eepLoc = EEP_START + ((uint16_t)idx * STRU_SIZE) ;
>
> eeprom_write_block((const void *)&setPgm, (void *)eepLoc, STRU_SIZE) ;
>
> return ;
> }
> //-------------------------------------------------------
> //Retreive struct from an indexed location in EEPROM....
> void getPgm(char idx)
> {
> eepLoc = EEP_START + ((uint16_t)idx * STRU_SIZE) ;
>
> eeprom_read_block((void *)&setPgm, (const void *)eepLoc, num) ;
>
> return ;
> }
> //------------------------------------------
> int main(void)
> {
> index = 5 ;
>
> setPgm.temp = 50 ;
> setPgm.time = 10 ;
>
> savPgm(index) ; //example .. save in 6th location in EEPROM;
>
> //Now read the saved struct back from eeprom...
>
> // this reads back correctly.:-
> setPgm.temp = eeprom_read_word((const uint16_t *)eepLoc) ; //eepLoc was
> set before.
> setPgm.time = eeprom_read_word((const uint16_t *)eepLoc + 1) ;
>
> //But this reads 0xFFFF for both elementss. (Why?):-
> getPgm(index) ; //uses block-read function
>
> return 0 ;
> }
> //---------------------------------------------------------------
> The getPgm function uses the read block api but retreives garbage(0xFFFF);
> What am I doing wrong ?
>
> Thank you!
> --
> Best Regards,
>
> -- Royce Pereira
>
> --
> Best Regards,
>
> -- Royce Pereira
>
--
Best Regards,
-- Royce Pereira
