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TI Home » TI E2E Community » Support Forums » Amplifiers » Precision Amplifiers » Precision Amplifiers Forum » Wrong data after writing the EEPROM from a PGA309
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Wrong data after writing the EEPROM from a PGA309

Wrong data after writing the EEPROM from a PGA309

This question is answered
Royke
Posted by Royke
on May 14 2012 03:39 AM
Intellectual490 points

In our system we are using the PGA309 frontend and we control it trough a microcontroler with the One-wire Interface.
After we write the complete EEPROM, we read the ZeroDAC register and we get a wrong answer from the PGA309. It returns 0x5449 ("TI") instead of the DAC value.
After 1 second of communication silence we read the correct value. Is this normal way to do it?

Programming on OMAP L138, LogicPD evm board 

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  • Ian Williams
    Posted by Ian Williams
    on May 14 2012 14:27 PM
    Verified Answer
    Verified by Ian Williams
    Genius14235 points

    Hello Royke,

    While 0x5449 is the TI Flag value in the external EEPROM, 0x5449 is also a valid setting for the Zero DAC register. Is this always the value read during this sequence or is there any variance?

    In normal operation, the PGA309 reads back from the EEPROM roughly once per second. How soon are you reading back the register after performing an EEPROM write? It's possible that not enough time has passed for the PGA309 to initiate an EEPROM read and update its registers. Once you allow the second to pass, it has been properly updated.

    Best regards,

    Ian Williams
    Linear Applications Engineer
    Precision Analog and Sensing Products 


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  • Royke
    Posted by Royke
    on May 15 2012 01:57 AM
    Intellectual490 points

    Hi Ian,

    Thanks for your reaction. Here are some answers on your questions.

    Is this always the value read during this sequence or is there any variance?

    Yes, when I write the EEPROM and then read the registers, I always get "TI" on the zeroDAC register. ALso other register values  seems to be shifted some places.
    I also tried to read 50 times the zeroDAC just after writing the EEPROM, but the value stays "TI".
    After 1 second of none comunication the register values are what they should be.

    But your reaction answers my question, after writing the EEPROM, I have to wait 1 second before the new values are placed in the PGA309 registers.

    Kind Regards,

    Royke 

     

    Programming on OMAP L138, LogicPD evm board 

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