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How can i use internal eeprom of atmega 8

Discussion in 'AVR' started by arkani, Oct 23, 2008.

  1. arkani

    arkani New Member

    Joined:
    Oct 11, 2008
    Messages:
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    Hello
    i want to use internal eeprom of atmega8 microcontroller but i dont know how use it .
    I use basic compailer ( bascom avr)
    Any one can hellp me?

    Thanks
     
  2. tivoi

    tivoi New Member

    Joined:
    Jan 22, 2006
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    WRITEEEPROM
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    Action

    Write a variables content to the DATA EEPROM.





    Syntax

    WRITEEEPROM var , address





    Remarks

    var
    The name of the variable that must be stored

    address
    The address in the EEPROM where the variable must be stored.



    A new option is that you can provide a label name for the address. See example 2.




    This statement is provided for compatibility with BASCOM-8051.



    You can also use :

    Dim V as Eram Byte 'store in EEPROM

    Dim B As Byte 'normal variable

    B = 10

    V = B 'store variable in EEPROM



    When you use the assignment version, the data types must be the same!



    According to a data sheet from ATMEL, the first location in the EEPROM with address 0, can be overwritten during a reset. It is advised not to use this location.



    For security, register R23 is set to a magic value before the data is written to the EEPROM.

    All interrupts are disabled while the EEPROM data is written. Interrupts are enabled automatic when the data is written.



    It is advised to use the Brownout circuit that is available on most AVR processors. This will prevent that data is written to the EEPROM when the voltage drops under the specified level.



    When data is written to the EEPROM, all interrupts are disabled, and after the EEPROM has been written, the interrupts are re-enabled.





    See also

    READEEPROM





    ASM

    NONE





    Example

    '-----------------------------------------------------------------------------------------

    'name : eeprom2.bas

    'copyright : (c) 1995-2005, MCS Electronics

    'purpose : shows how to use labels with READEEPROM

    'micro : Mega48

    'suited for demo : yes

    'commercial addon needed : no

    '-----------------------------------------------------------------------------------------



    $regfile = "m48def.dat" ' specify the used micro

    $crystal = 4000000 ' used crystal frequency

    $baud = 19200 ' use baud rate

    $hwstack = 32 ' default use 32 for the hardware stack

    $swstack = 10 ' default use 10 for the SW stack

    $framesize = 40 ' default use 40 for the frame space



    'first dimension a variable

    Dim B As Byte

    Dim Yes As String * 1



    'Usage for readeeprom and writeeprom :

    'readeeprom var, address



    'A new option is to use a label for the address of the data

    'Since this data is in an external file and not in the code the eeprom data

    'should be specified first. This in contrast with the normal DATA lines which must

    'be placed at the end of your program!!



    'first tell the compiler that we are using EEPROM to store the DATA

    $eeprom



    'the generated EEP file is a binary file.

    'Use $EEPROMHEX to create an Intel Hex file usable with AVR Studio.

    '$eepromhex



    'specify a label

    Label1:

    Data 1 , 2 , 3 , 4 , 5

    Label2:

    Data 10 , 20 , 30 , 40 , 50



    'Switch back to normal data lines in case they are used

    $data



    'All the code above does not generate real object code

    'It only creates a file with the EEP extension



    'Use the new label option

    Readeeprom B , Label1

    Print B 'prints 1

    'Succesive reads will read the next value

    'But the first time the label must be specified so the start is known

    Readeeprom B

    Print B 'prints 2



    Readeeprom B , Label2

    Print B 'prints 10

    Readeeprom B

    Print B 'prints 20



    'And it works for writing too :

    'but since the programming can interfere we add a stop here

    Input "Ready?" , Yes

    B = 100

    Writeeeprom B , Label1

    B = 101

    Writeeeprom B



    'read it back

    Readeeprom B , Label1

    Print B 'prints 1

    'Succesive reads will read the next value

    'But the first time the label must be specified so the start is known

    Readeeprom B

    Print B 'prints 2

    End
     

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