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  1. #1
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    28C256 EEPROM Problem, Data automatically corrupt

    Hi friends, I have a problem using 28c256 EEPROM Chip. In a Chick Master Hatcher machine Board company use 28C256 Chip. I copy Data from original chip and program it in a new AT28C256 IC. Copied IC work well and oprate all the functions correct but after 3 or 4 hours (some time one day) IC software automatically corrupt and not operate properly. The orignal company IC work fine in the same circuit Board. I bout many new ICs but the problem is same.
    Please cane anyone help me to solve the problem and is there any comparison of 28C256?

    Thanks.

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    Re: 28C256 EEPROM Problem, Data automatically corrupt

    You try to compare the two manufacturers data for the two IC's. There seems to be supply voltage issue like 3 or 5 V or some thing similar.
    After working for sometime it starts malfunctioning. Please check if it recovers on standing for some time or the data content is corrupt or lost.



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  3. #3
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    Re: 28C256 EEPROM Problem, Data automatically corrupt

    Read datasheet for your EEPROM. It has additional software write protection:

    The CAT28C256 features a software controlled data protection scheme which, once enabled, requires a data algorithm to be issued to the device before a write can be performed. The device is shipped from Catalyst with the software protection NOT ENABLED (the CAT28C256 is in the standard operating mode). To activate the software data protection, the device must be sent three write commands to specific addresses with specific data (Figure 9). This sequence of commands (along with subsequent writes) must adhere to the page write timing specifications (Figure 11). Once this is done, all subsequent byte or page writes to the device must be preceded by this same set of write commands. The data protection mechanism is activated until a deactivate sequence is issued regardless of power on/off transitions. This gives the user added inadvertent write protection on power-up in addition to the hardware protection provided.
    I can guess that you have not enabled the software protection in new chip, but old original chip was written with software protection.



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    Re: 28C256 EEPROM Problem, Data automatically corrupt

    The original chip is X28HC256, I use AT28C256. Supply voltages is same of both chips (5 Volt) and after some time data content was corrupt, not lost. How can I do software protection.
    Last edited by kg300; 18th December 2011 at 17:16.



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    Re: 28C256 EEPROM Problem, Data automatically corrupt

    May be suggestions of post #3 seems worth considering and trying. Please give it a thought !
    The animated pic on the left of post #3 is funny !!
    Raoof



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  6. #6
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    Re: 28C256 EEPROM Problem, Data automatically corrupt

    Is it possible to add software write protection in Hex file? Because I just copy the data from original chip in hex format.



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    Re: 28C256 EEPROM Problem, Data automatically corrupt

    No, you can not add software write protection simply by changing hex file. Read datasheet for this chip. You will find write sequence to enable protection.

    http://www.atmel.com/dyn/resources/p...ts/doc0006.pdf

    You need to read page #10.



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    Re: 28C256 EEPROM Problem, Data automatically corrupt

    Just use 29Fxxx flash memory. It is pin-to-pin compatible.



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