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Thread: Hi all eeprom

  1. 21st June 2004 08:10 AM #1
    TKS
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    Default Hi all eeprom

    what could be the problem when you write something to a eeprom and you read another symbol from it ..??


    i use a 20Mhz (osc) pic could it be the bus speed to high..???


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  2. 21st June 2004 08:20 AM #2
    Nigel Goodwin
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    Default

    You don't say what kind of EEPROM you are trying to write, but I'm presuming it's an I2C one?. A 20MHz PIC can certainly write out faster than an I2C EEPROM can receive it, your code should be written accordingly, bearing in mind the speed limitations of the EEPROM - you can get those details from the datasheet.

    You could also have a problem with your I2C routines, have a look at my I2C tutorial for software I2C code which I know works. If you're trying to use the I2C hardware in the 16F877, I have heard it's very difficult to get working, and that the application notes from MicroChip don't work.
    PIC programmer software, and PIC Tutorials at:
    http://www.winpicprog.co.uk
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  3. 21st June 2004 08:24 AM #3
    TKS
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    Default ...

    i'm using

    pic compiler and i just grabbed 2 ports who where free..

    (d.0 & d.1)

    and wired it up like your tut (whit the 9K res..)

    i think its the speed i will write my own routine.. whit delays..

    ionstead of the basic commands..

    (in the help i read something about the speed limit)
    but i turned the slof_bus=on ..i will see..

    TKS
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  4. 21st June 2004 08:41 AM #4
    StupidDum
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    Default

    Try to put longer delay. PIC at 20Mhz is much faster then EEPROM .
    I now face a problem on I2C.

    I have written code for Atmel 24C64 i2c EEPROM, it works just fine.
    Now i use Microchip 24LC64, but that just wont work.
    I've checked the timing spec, both are almost identical.
    I'd appreciate it if anyone could tell me the reason.
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  5. 21st June 2004 08:44 AM #5
    TKS
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    Default i also have

    lying a pair of those atmels around...

    i think it are the config bits..??

    or something near like the control byte..???


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