avr and eeprom problema and how to halt cycles in programming

[deepakgupta.rf]

hello everyone
some time what i feel ,my atmega8535 do not read eeprom value.
it process all the work properly but sometime it not read values from eeprom.again when i do reset ,then it works proper and show numbers exactly.


for(k=0;k<=29;k++)
{
numb[k]= eeprom_read_byte(k);
delay_ms(200);
}


///// eeprom write////////////
/


void write_eeprom_byte(char address, char data)
{
// EEARH=0x00;
// EEARL = address ;

while(EECR & 0x02 == 1) ; // CHECK EEWE BIT

while( SPMCR & 0x01 == 1); // CHECK SPMEN BIT

// EEARH=0x00; // SET ADDRESS MSB BYTE
EEARL = address ; // SET LSB BYTE OF ADDRESS
EEDR = data ; // WRITE data to be written to EEPROM
EECR = 0x04 ; // SET EEMWE BIT
#asm
// nop;
// nop;

#endasm
EECR = 0x06; // SET EEMWE & EEWE BITS

while(EECR & 0x04 == 1); // CHECK EEMWE IS CLRED


// delay_ms(10); // general delay

return;


}


////// eeprom read/////////////////////////////

char eeprom_read_byte(char address)
{
char data=0;

while(EECR & 0x02 == 1) ; // check EEWE BIT IS CLRed

// EEARH=0x00; // SET MSB BYTE OF ADDRESS
EEARL = address ; // SET LSB BYTE OF ADDRESS

EECR = 0x01 ; // SET EERE BIT

#asm
// nop;
// nop;

#endasm

data = EEDR; // read data from the EEPROM

return(data); // RETURN EEPROM data value


}


so sir plz what is the basic problem

 

[majoka]

reading function is ok u write
if problem not solved u can write asm code in c function and also c code is given in its data sheet
anyhow

Code:

; WRITE INTERNAL EEPROM
; Data to Write: R30
; Adress Hi Byte: R29
; Adress Lo Byte: R28
;
WRITE_EEPROM: PUSH R30 ; Store write value to stack
RCALL READ_EEPROM ; Check if value to write is same as content of EEPROM cell
MOV R31, R30 ; Move the current content of the EEPROM cell to R31
POP R30 ; Restore write value from stack
CP R30, R31 ; Compare current EEPROM content with new value
BRNE WAIT_EEWE ; If it is not equal, then write it
RET ; Don't stress EEPROM if the value is already there ...
WAIT_EEWE: SBIC EECR, EEWE ;
RJMP WAIT_EEWE ; wait until bit EEWE in EEPROM Control Register is clear
WAIT_SPMEN: IN R31, SPMCR ;
sbrc R31, SPMEN ;
RJMP WAIT_SPMEN ; wait until bit SPMEN in SPMCR is clear
OUT EEARH,R29 ; output address high
OUT EEARL,R28 ; output address low
OUT EEDR,R30 ; output data
SBI EECR,EEMWE ; set master write enable
SBI EECR,EEWE ; set EEPROM Write strobe
RET ;

;
; READ INTERNAL EEPROM
; Adress Hi Byte: R29
; Adress Lo Byte: R28
; Read Data : R30
;
READ_EEPROM: SBIC EECR,EEWE ; if EEWE not clear
RJMP READ_EEPROM ; wait more
OUT EEARH,R29 ; EEPROM address high
OUT EEARL,R28 ; EEPROM address low
SBI EECR,EERE ; set EEPROM Read strobe
IN R30,EEDR ; get data
RET ;

And don't forget to set these fuses:
Brown-out detection level at VCC=2.7 V
Brown-out detection enabled
or your eeprom may get corrupted during power on/off

 

[muthurajsakthi]

actually which complier you are using